THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 


PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 
MRS.  PRUDENCE  W.  KOFOID 


k-CP29 
D3 

1809 
v.l 


ZOONOMIA ; 


OR  THE 


LAWS  OF  ORGANIC  LIFE. 

IN  Tiaf  YiliiPAT?rrQ 


BY*  ERASMUS  DARWIN,  M.  D.  F.R.S. 

S»l  it* 'II 

AUTHOR  OF  THE  BOTAXIC  GARDEN,  PHYTOLOGIA,  &C. 


Principio  coelum,  ac  terras,  campofque  liqucntes, 
Lucentemque  globum  lun.T,  titaniaque  aflra, 
Spiritus  intus  alit,   totamque  infufa  per  artus 
Mens  agitat  malem,  et  magno  fe  corpore  mifcet. 

VIRG.  JEn.  vi. 

Earth,  on  whofe  lap  a  thoufand  nations  tread, 

And  Ocean,  brooding  his  prolific  bed, 

Night's  changeful  orb,  blue  pole,  and  filvery  zones, 

Where  other  worlds  encircle  other  funs, 

One  mind  inhabits,  one  diffufive  Soul 

Wields  the  large  limbs,  and  mingles  with  the  whole. 


COMPLETE   IN  TWO  VOLUMES. 


VOLUME  I. 

THIRD  AMERICAN  EDITION. 


BOSTON : 

PUBLISHED    BY  THOMAS   &  ANDREWS, 
No.  45,  NEWBURY-STREET. — 1809. 

%  r.  BUCKINGHAM,  PRINTER,  JFINTHR-STREEr. 


Ikftl 


Dedication* 


o          n 


o  trie  candid  and   I 

of  trie  Csolteae  o 
o/  trie  &loUai>  ^ 
trie  ^7n^o  Mnlv-erditiej  ,  and  to  ail 

nt-rio  /tadu  trie  (Jfievattond  of  trie 

/  / 

at  a  tJctcnce,  or  wrio  fitacttte 

a  wrofefalon,  trie  Javjeauent  rrorh 

If  '      <X  / 

areat  vetfiect,  inj&ufred  vu 


u 


rl  TO  ERASMUS  DARWIN. 

Now  in  ftrong  lines,  with  bolder  tints  defign'd, 
You  {ketch  ideas,  and  portray  the  mind  ; 
Teach  how  fine  atoms  of  impinging  light 

To  ceafelefs  change  the  vifuai  fenfe  excite:  40 

While  the  bright  lens  collects  the  rays,  that  fwerve, 
And  bends  their  focus  on  the  moving  nerve. 
How  thoughts  to  thoughts  are  link'd  with  viewlefs  chains, 
Tribes  leading  tribes,  and  trains  purfuing  trains  ; 
With  fhadowy  trident  how  Volition  guides,  45 

Surge  after  furge,  his  intellectual  tides; 
Or,  Queen  of  Sleep,  Imagination  roves 
With  frantic  Sorrows,  or  delirious  Loves. 

Go  on,  O  FRIEND  !  explore  with  eagle  eye, 

Where  wrapt  in  night  retiring  Caufes  lie  :  50 

Trace  their  flight  bands,  their  fecret  haunts  betray, 
And  give  new  wonders  to  the  beam  of  day  ; 
Till,  link  by  link,  with  ftep  afpiring  trod, 
You  climb  from  NATURE  to  the  throne  of  GOD. 

So  faw  the  Patriarch  with  admiring  eyes,  55 

From  earth  to  heaven  a  golden  ladder  rife  ; 
Involv'd  in  clouds  the  myftic  fcale  afcends, 
And  brutes  and  angeis  crowd  the  diflant  ends. 

TRIN.  COL.  CAMBRIDGE,  Jan.  1,  1794. 


REFERENCES. 


Botanic  Garden,  Part  I. 
Canto  I.  1.  105 
—  IV.  1.  402 
I.  1.  140 

III.  1.  401 

IV.  1.  452 
I.      1.     14 


Zoonomia. 
.  12.  Sea.  XIII. 
.13.  XXXIX.  4.  1. 


Sea.   XVI.  2.  and  XXXVIII. 

XVI.  4. 

XVI.  4. 

XVI.  6. 

HI.  and  VII. 

X. 

XVIII.   17. 

XVII.  3.  7. 

XVIII.   8. 

XXXIX.  4.  8. 

-  XXXIX.  the  Motto, 

XXXIX.  8. 


PREFACE. 


THE  purport  of  the  following  pages  is  an  endeavour 
to  reduce  the  fads  belonging  to  ANIMAL  LIFE  into 
clafles,  orders,  genera,  and  fpecies ;  and,  by  comparing 
them  with  each  other,  to  unravel  the  theory  of  difeafes. 
It  happened,  perhaps  unfortunately  for  the  inquirers  in- 
to the  knowledge  of  difeafes,  that  other  fciences  had  re- 
ceived improvement  previous  to  their  own  ;  whence,  in- 
ftead  of  comparing  the  properties  belonging  to  animated 
nature  with  each  other,  they,  idly  ingenious,  bufied  them- 
felves  in  attempting  to  explain  the  laws  of  life  by  thofe 
of  mechanifm  and  chemiftry  ;  they  confidered  the  body 
as  an  hydraulic  machine,  and  the  fluids  as  paffing  through 
a  feries  of  chemical  changes,  forgetting  that  animation 
was  its  eflential  charaderiftic. 

The  great  CREATOR  of  all  things  has  infinitely  diver- 
fified  the  works  of  his  hands,  but  has  at  the  fame  time 
ftamped  a  certain  fimilitude  on  the  features  of  nature, 
that  demonftrates  to  us,  that  the  whole  is  one  family  of 
one  parent.  On  this  fimilitude  is  founded  all  rational 

analogy ; 


Vlll 


PREFACE. 


analagy  ;  which,  fo  long  as  it  is  concerned  in  compar- 
ing the  eflential  properties  of  bodies,  leads  us  to  many 
and  important  difcoveries  ;  but  when  with  licentious  ac- 
tivity it  links  together  objeds,  otherwife  difcordant,  by 
fome  fanciful  fimilitude  ;  it  may  indeed  colled  orna- 
ments for  wit  arid  poetry,  but  philofophy  and  truth  re- 
coil from  its  combinations. 

The  want  of  a  theory,  deduced  from  fuch  ftrict  anal- 
ogy, to  conduct  the  practice  of  medicine,  is  lamented  by 
its  profeflbrs  ;  for,  as  a  great  number  of  unconnected 
fads  are  difficult  to  be  acquired,  and  to  be  reafoned  from, 
the  art  of  medicine  is  in  many  inftances  lefs  efficacious 
under  the  direction  of  its  wifeft  practitioners  ;  and  by 
that  bufy  crowd,  who  either  boldly  wade  in  darknefs,  or 
are  led  into  endlefs  error  by  the  glare  of  falfe  theory,  it 
is  daily  pradifed  to  the  deftrudion  of  thoufands  ;  add 
to  this  the  unceafmg  injury  which  accrues  to  the  public 
by  the  perpetual  advertifements  of  pretended  noftrums  \ 
the  minds  of  the  indolent  become  fuperftitioufly  fearful 
of  diieafes,  which  they  do  not  labour  under  ;  and  thus 
become  the  daily  prey  of  fome  crafty  empyric. 

A  theory  founded  upon  nature,  that  fhould  bind  to- 
gether the  fcattered  fads  of  medical  knowledge,  and  con- 
verge into  one  point  of  view,  the  laws  of  organic  life, 
would  thus  on  many  accounts  contribute  to  the  intereft 
of  fociety.  It  would  capacitate  men  of  moderate  abili- 
ties to  pradife  the  art  of  healing  with  real  advantage  to 
the  public  ;  it  would  enable  every  one  of  literary  ac- 
quirements to  diftinguifh  the  genuine  difciples  of  medi- 
cine from  thofe  of  boaftful  effrontery,  or  of  wily  addrefs  ; 
and  would  teach  mankind  in  fome  important  fituations 
the  knowledge  of  themf elves. 

There 


PREFACE.  ix 

There  are  fome  modern  praftitioners,  who  declaim  a- 
gainft  medical  theory  in  general,  not  confidering  that  to 
think  is  to  theorize  ;  and  that  no  one  can  direft  a  me- 
thod of  cure  to  a  perfon  labouring  under  difeafe  without 
thinking,  that  is,  without  theorizing  ;  and  happy  there- 
fore is  the  patient,  whofe  phyfician  poffefies  the  beft 
theory. 

The  words  idea,  perception,  fenfation,  recolle&ion, 
fuggeftion,  and  aflbciation,  are  each  of  them  ufed  in  this 
treatife  in  a  more  limited  fenfe  than  in  the  writers  of 
metaphyfic.  The  author  was  in  doubt,  whether  he 
ihould  rather  have  fubftituted  new  words  inftead  of 
them  ;  but  was  at  length  of  opinion,  that  new  defini- 
tions of  words  already  in  ufe  would  be  lefs  burthenfome 
to  the  memory  of  the  reader. 

A  great  part  of  this  work  has  lain  by  the  writer  above 
twenty  years,  as  fome  of  his  friends  can  teftify  :  he  had 
hoped  by  frequent  revifion  to  have  made  it  more  worthy 
the  acceptance  of  the  public  ;  this  however  his  other 
perpetual  occupations  have  in  part  prevented,  and  may 
continue  to  prevent,  as  long  as  he  may  be  capable  of  re- 
vifing  it ;  he  therefore  begs  of  the  candid  reader  to  ac- 
cept of  it  in  its  prefent  ftate,  and  to  excufe  any  inaccu- 
racies of  expreffion,  or  of  conclufion,  into  which  the  intri- 
cacy of  his  fubjeft,  the  general  imperfe£Uon  of  lan- 
guage, or  the  frailty  he  has  in  common  with  other  men, 
may  have  betrayed  him  ;  and  from  which  he  has  not  the 
vanity  to  believe  this  treatife  to  be  exempt. 


VOL,  I. 


PREFACE 


TO 

THE  THIRD  LONDON  EDITION. 


THE  Reader  fhould  be  apprized,  that  many  new  pa- 
ges are  interfperfed  in  this  edition,  which  confift  of 
practical  and  theoretical  obfervations,  as  the  whole  arti- 
cles on  Hemicrania  idiopathica,  retroverfio  uteri,  aneu- 
rifma,  and  the  appendix  to  the  fedion  on  Generation, 
beginning  at  No.  8.  as  well  as  the  diftindion  between 
philofophy  and  fophiftry  in  Se£t  XV.  i.  5.  and  the  Ra- 
tiocinatio  verbofa,  verbal  reafoning,  in  Clafs  III.  i.  2.  3. 
and  fome  others. 

Derby,  Jan.  1,  1801. 


r3"  IN  the  former  editions  of  this  work  the  MATERIA 
MEDICA  [which  forms  Part  III.]  was  placed  after  the 
fecond  part,  or Jthe  clafles  of  difeafes  ;  but  to  preferve 
the  more  equalfee  of  the  volumes  in  this  odavo  edition, 
the  publifher  has  placed  it,  with  the  aflent  of  the  author, 
after  the  firft  part. 


CONTENTS. 


PART    I. 

Page 

SECT.    I,  Of  Motion      -  i 

II.  Explanations  and  Definitions  3 

III.  The  Motions   of  the  Retina  demonilrated  by 

Experiments  -       8 

IV.  Laws  of  Animal  Caufation     -  20 
V.  Of  the  four  Faculties  or  Motions  of  the  Sen- 

forium  -     2  r 

VI.  Of  the  four  Clafles  of  Fibrous  Motions  23 

VII.  Of  Irritative  Motions  -     25 

VIII.  Of  Senfitive  Motions      -  29 

IX.  Of  Voluntary  Motions      -  -     3 1 

X    Of  Aflbciate  Motions     -  34 

XI.  Additional   Obfervations    on  the    Senforial 

Powers  -     37 
XII.  Of  Stimulus,  Senforial  Exertion,  and  Fibrous 

Contraction  43 

XIII.  Of  Vegetable  Animation    -  -         -         -     73 

XIV.  Of  the  Produftion  of  Ideas  79 
XV.  Of  the  Clafles  of  Ideas       -  -         -         -     oc 

XVI.  Of  Inftinft  -                   10 1 
XVII.  The  Catenation  of  Animal  Motions    -         -     147 
XVIII.  Of  Sleep  153 
XIX.  Of  Reverie      -  170 
XX.  Of  Vertigo  -         -         -         175 
XXI.  Of  Drunknennefs     -  -191 
XXII.  Of  Propenfity  to  Motion.  Repetition.     Im- 
itation     -  198 

XXIII.  Of  the  Circulatory  Syflem  -     206 

XXIV.  Of  the  Secretion  of  Saliva,  and   of  Tears. 

And  of  the  Lachrymal  Sack  -         212 

XXV.  Of  the  Stomach  and  Inteftines  -         -         -     217 
XXVI.  Of  the  Capillary   Glands,  and  of  the  Mem- 
branes     -  226 
XXVII.  Of  Haemorrhages     -         -         -         -               229 
XXVIII.  The  Paralyfis  of  the  Ladeals                             234 

SECT. 


xiv  CONTENTS. 

Page 
SECT.  XXIX.  The  Retrograde  Motions  of  the  Abforbent 

VefTels      -  -  -     238 

XXX.  The  Paralyfis  of  the  Liver  and  Kidneys         272 

XXXI.  Of  Temperaments     -         -         -         -        277 

XXXII.  Difeafes  of  Irritation     -  -     282 

XXXIII. of  Senfation          -         -         -         30 c 

XXXIV.  of  Volition      -  -     324 

XXXV.  of  AiTociation       -         -         -         343 

XXXVI.  The  Periods  of  Difeafes  -  352 

XXXVII.  Of  Digeftion,  Secretion,  Nutrition      -  360 
XXXVIII.  Of  the  Oxygenation  of  the  Blood  in  the 

Lungs  and  Placenta        -         -         -  366 

XXXIX.  Of  Generation     -  -  373 

XL.  Of  Ocular  Speftra     -  443 

[PART  II.  forms  the  Second  Volume.] 


PART  III. 

ARTICLES   OF   THE  MATERIA    MEDICA. 

ART.  I.  Nutrientia   -  -                  -    Page  5 

II.  Incitantia  -                   19 

III.  Secernentia  -                            -     31 

IV.  Sorbentia  -                            42 
V.  Invertentia  -         -     65 

VI.  Revertentia    -  70 

VII.  Torpentia  -                                   -    73 


INTRODUCTION 


TO 


THE  AMERICAN  EDITION. 


CONTENTS  OF  THE  INTRODUCTION. 

OljeB  of  thejirfl  part  of  the  Zoonomia.  Arrangement  of  Irving  motions. 
Functions  referable  to  each  of  thefe.  Clarification  of  animated  aclion 
under  four  heads.  Influence  of  jiimuli  in  Jujlaimng  life.  Comparifon 
of  Dr.  Darwin's  dofirine  of  Jlimulus  and  exertion  with  the  Brunonian 
Elements.  Great  refemblance  acknowledged  by  the  former.  Which  of 
them  was  indebted  to  the  other  ?  The  two  authors  efpoufe Jimilar  funda- 
mental principles.  Examination  of  the  Jlander  that  Brown's  doclrinc 
was  but  a  revival  of  the  opinions  of  the  ancient  Methodic  SecJ.  Hifto- 
ry  of  thatfefl.  A  branch  of  the  Epicureans.  Sketch  of  the  Epicurean 
philofophy.  Application  of  this  to  medicine.  Reafoning  wholly  mechan- 
ical. Hi/lory  of  the  opinions  concerning  life  fuperadded  to  mechanifm, 
from  Hippocrates  to  Cullen.  How  far  the  latter  had  proceeded.  Mer- 
its of  Brown.  Abftrafi  of  thejirjl  edition  of  his  Ekmenta^  publi/hed  in 
1780,  and  now  very  rare.  Review  of  his  fecond  edition,  in  1784. 
The  Engli/h  work  a  mere  tranflation  of  this.  Epitome  of  the  Bruno- 
nian DocJrine.  Very  different  from  the  notions  of  Themifon  and  Thef- 
falus.  Defefts  in  Brown's  fyilem.  Room  for  improvements.  Great 
amendments  made  by  various  perfons.  Introduction  of  chemical  princi- 
ples and  modes  of  reafoning.  Infufficient  to  explain  the  phenomena  of 
life.  Laudable  attempt  of  Dr.  Darwin  to  inveftigate  thofe  laws  which 
neither  mechanifm  nor  chemiftry  can  explain.  ObjecJ  of  the  fecond  part 
to  form  a  nofology,  or  catalogue  of  difeafis,  by  a  natural  clajfification, 
founded  on  their  proximate  caufes. 

AN  attempt  has  been  made  in  the  firft  part  of  this  work  to  in- 
vetfigate  the  complex  laws  of  animal  caufation.     Thefe  are  de- 
duced from  the  contractions  and  relaxations  performed  by  the  living 
fibres,  which  conftitute  the  mufcles  and  organs  of  fenfe.     Fibrous  con- 
tradlions    feem   to  conftitute  all   the  fun&ions  of  animated   bodies, 
and  indeed  all   we  know  both  phyfiologically  and  medically   con- 
cerning 


xvi  INTRODUCTION  TO  THE 

cerning  life  and  its  functions.  They  are  arranged  into  four  claff- 
es  of  motions  whicli  form  the  foundation  of  all  juft  nofology  and 
practice,  as  detailed  in  the  fecond  great  divifion  of  the  Zoonomia.  Vi- 
tal motions  are  thus  called  irritative,  fenjiti<ue ,  voluntary •,  and  affocnated^ 
according  as  the  parts  of  the  body  in  which  they  exift  are  endowed 
with  irritability  >  fenfation  volition,  Q\'  fympathy.  This  quadruple  allot- 
ment of  functions  forms  a  ftrong  and  peculiar  character  of  the  follow- 
ing work.  And  the  difrribution  of  the  almoft  endlefs  variety  of  ani- 
mated phenomena  into  this  fourfold  and  lucid  argument,  is  a  clear 
proof  of  the  difcriminating  and  generalizing  mind  of  the  author. 

But  in  all  thefe  conditions  of  the  fyftem,  whether  influenced  by  the 
vts  Injita  or  the  vis  ner<uea^  by  voluntary  or  fympathetic  energy,  the  fen- 
forial  powers  are  fuftained  by  the  unceafing  operation  of  STIMULANTS. 
The  theory  of  thefe  is  contained  in  the  twelfth  chapter  of  the  firftpart, 
and  exhibits  very  advantageoully  the  doctrine  of  ftimulus  and  exertion^ 
or  as  it  has  been  more  generally  called,  excitement. 

There  is  a  finking  analogy  between  thefe  fundamental  doctrines  of 
Dr.  Darwin  and  thofe  contained  in  Dr.  Brown's  Elements  of  Medicine. 
Our  author  was  aware  of  this,  and  to  guard  himfelf  againft  the  impu- 
tation of  having  borrowed  Brown's  ideas  without  acknowledgment,  or 
of  being  merely  his  imitator,  he  obferves  that  "  the  coincidence  of 
"  fome  parts  of  this  work  with  correfpondent  deductions  in  the  Bru- 
"  nonian  Elementa  Medicinae,  a  work  {with  fome  exceptions)  of  great 
"  genius,  muft  be  confidered  as  confirmations  of  the  truth  of  the 
"  theory,  as  they  were  probably  arrived  at  by  different  trains  of  rea- 
"  foning  " 

In  refpect  to  originality  there  is  great  difficulty  in  fettling  claims. 
In  this  cafe  however,  there  is  not  even  a  fufpicion  that  Brown  derived 
any  thing  from  Darwin.  Both  might  indeed  have  come  to  fimilar 
conclufions,  by  the  independent  exercife  of  their  reafon,  without  any 
communication  or  intcrcourfe,  And  yet,  an  impartial  obferver,  prone 
neither  to  obloquy  nor  flattery,  would  not  forfeit  his  candour  in  fuf- 
pecting  that  a  writer  of  Darwin's  acutenefs  might  have  gathered  fome- 
thing  from  Brown,  who  publifhed  fourteen  years  before  him. 

Confidering  the  Brunonian  and  Darwinian  fyftems  as  refting  upon 
the  fame  pillars,  it  appears  to  me  there  may  be  both  ufefulnefs  and  cu- 
riofity  in  Searching  and  digging  about  the  ground  on  which  they  ftand. 
In  performing  this  taik,  it  has  been  expected  there  fhould  be  a  ftate- 
inent  mewing  how  far  thefe  doctrines  of  the  Scottifh  and  Englifh  phy- 
ficians  are  themfelves  novel  or  modern,  or  whether  they  are  both  of 
the  old  fchool  and  derived  from  remote  and  ancient  fources. 

By  deciding  in  favour  of  their  modernity,  it  will  be  likewife  expect- 
ed that  a  view  mould  be  given  of  the  Brunonian  fyftem,  that  it  may 
be  compared  with  the  cotemporary  doctrines  of  Cullen  and  Darwin. 
In  this  comparifon  it  will  be  found,  that  Brown's  merit  is  very  con- 
fpicuous.  The  three  diflinguiflied  authors  have  finifhed  their  earthly 
career,  and  they  and  their  writings  may  now  be  confidered  without 
envy  or  partiality.  To  thofe  who  are  Curious  to  trace  the  progrefs 
of  thefe  opinions,  which  exert  fuch  extenfive  dominion  over  the  mind, 

thefe 


AMERICAN  EDITION.  xvii 

^thefe  introduftory  remarks  may  perhaps  afford  fome  gratification. 
Others,  who  porTefs  not  the  tafte  or  leifure  for  fuch  enquiries,  raay  pafs 
them  over,  and  in  the  progrefs  of  obfervation  and  experiment  in  phyfics, 
within  a  few  years,  fuch  a  number  of  new  and  important  facts  have 
been  brought  to  light,  that  many  philofophers  have  believed  the  peo- 
ple of  the  prefent  day  were  pofTeffed  of  a  great  deal  more  knowledge 
than  the  moderns  of  the  three  laft  centuries,  or  their  ancieot  prede- 
ce/Tors. 

This  opinion,  in  particular,  has  been  deemed  well  founded,  and  true 
in  its  refpect  to  medicine,  which,  at  this  time,  is  not  only  confidered 
fufceptible  of  new  expofitions  and  interpretations,  but  of  being  great- 
ly improved  and  enlarged,  both  in  theory  and  practice.  And  although 
among  thofe  who  think  thus  are  reckoned  moft  of  the  original  and  clear 
fighted  geniufes  of  our  time,  yet  there  are  not  wanting  fome,  and  thofe 
iften  of  talents  and  reputation  too,  who  are  in  the  habit  of  thinking,  if 
the  ancients  knew  not  quite  as  much  as  ourfelves,  yet  their  writings 
contain  the  leading  hints,  or  great  outlines  of  almoft  every  thing  dif- 
coverable,  either  directly  exprefled,  or  fignified  in  allegorical  terms. 
This  literary  fuperftition  has  been  carried  a  great  way  ;  and  if  it  had 
flopped  at  declaring  the  Iliad  the  belt  of  poffible  poems,  or  the  Pkil- 
lipics  the  moft  finifhed  of  the  rhetorical  productions,  I  mould  not  at 
this  time  have  troubled  myfelf  to  contradict  it.  But  when  thefe 
enthufiaftic  admirers  of  antiquity  declare,  that,  in  matters  of  fcience  as 
well  as  of  letters,  the  fubjects  of  enquiry  have  been  exhaufted  two 
thoufand  years  ago,  and  that  no  idea  can  be  (rarted  which  is  not  an 
imitation  of  fomething  that  a  Greek  or  a  Roman,  or  fome  body  elfe, 
had  thought  before,  I  own  I  am  a  little  difpofed  to  believe  their 
aflertions  are  grounded  neither  in  truth  nor  in  the  nature  of  things. 
For  why  muft  we  refort  to  the  PLATONISTS,  STOICS,  and  PERIPA- 
TETICS, for  doctrines  which  the  ACADEMY,  the  PORCH,  and  the  LY- 
CEUM never  knew  ? 

Thefe  remarks  are  made  in  confequence  of  an  opinion,  propagated 
and  believed  by  fome,  that  a  certain  method  of  reafoning  upon  medical 
fubjects,  and  of  medical  practice  introduced  now  of  late  as  many  be- 
lieve, which  are  already  pretty  well  eftabli^hed,  and  acquiring  rapidly 
more  and  more  adherents,  are  in  fact  but  a  revival  and  new  modelling 
of  the  opinions  and  procedure  of  the  METHODIC  SECT,  founded  by 
ASCLIPIADES,  the  extemporary  of  MITHR.IDATIJS  and  CRASSUS 

In  order  to  know  whether  this  opinion  is  well  founded,  I  mail  en- 
quire what  the  philofophy  of  the  Methodic  .Sect  was. 

Its  founder,  ASCLEPIADES}  adopted  that  philofophy,  whofe  foun- 
dation had  been  laid  by  ANAXAGORAS,  JtMPtDocLEs,  and  HERACLI- 
TUS,  and  which  was  afterwards  wrought  up  into  the  Atomic  Sy/iem*  by 
LEUCIPPUS,  and  DEMOCRITUS,  ofthzE/wtic  Sift  ;  who,  rejecting  all 
metaphyfical  explanations  of  the  caufes  of  things,  undertook  the  inter- 
preting nature,  from  the  laws  of  matter  and  motion.  This  was  after- 
wards commented  upon,  enlarged  and  adorned  by  EPICURUS,  fo  as 
foform,  what  was  afterwards  called  the  Epicurean  Philofopby.  What 
:lie  details  of  this  are,  may  be  feen  in  DIOGENES  LAERTIUS,  in 

VOL.  L  £  ERUCKER 


xvin  INTRODUCTION  TO  THE 

BRUCKER  and.  his  tranflator  EN  FIELD,  as  well  as  in  the  poem  of  LU-* 
CRETIUS,  who  has  confefTedly  attempted  a  poetical  difplay  of  thefe 
very  doctrines.  A  general  view*  comprifing  a  mere  (ketch  of  the  fyf- 
tem  of  this  .A.Mi$eutl6$  or  felf-taught  man,  as  he  called  himfelf  as  far 
as  connected  with  the  prefent  fubject,  is  all  1  fhall  offer  here.  An 
Epicurean  would  explain  himfelf  thus  : — •'*  It  is  clear,  from  the  chang- 
"  es  which  natural  bodies  undergo,  that  there  is  a  perpetual  formation 
"  and  deftruclion  of  them  going  on  ;  there  muft  then  exift  matter  of 
"  which  thefe  things  are  formed,  and  into  which  they  are  refolved  ; 
<;  and  hence  proceeds  the  concludes  which  is  the  ground-work  of  the 
"  fyftem,  that  a  thing  can  neither  be  made  out  of  nothing,  nor  reduced 
"  to  nothing.  "  Nuilam  rem  e.  nlhilo  ,'tgm  druinitus  unquam"  The 
*c  univerfe,  therefore,  as  to  its  conftituent  atoms  or  particles,  was  al- 
"  ways  as  it  is  at  prefent  ;  and  confequently  matter  is  eternal  The 
"  workman  cannot  perform  any  thing  without  materials  ;  and  thefe 
**  feif-exiftent  materials,  in  the  decay  and  renovation  they  undergo,  ac- 
"  count  for  the  phenomena  of  nature  and  of  art.  If  things  were  ere- 
**  ated  out  of  nothing,  then  every  kind  mould  proceed  from  each,  and 
u  the  greateft  irregularity  enfue  ;  men  mould  be  produced  in  the  fea, 
"  fifties  on  the  land,  and  cattle  in  the  clouds  ;  generation  would  be  ufe- 
"  lefs,  and  food  unneceflary  :  if  they  returned  to  nothing,  then,  in  the 
*'  courfe  of  pall  agess  through  wafte,  confumption,  and  lofs,  much 
"  muft  have  vanimed  tonon-exiftence,  and  have  been  completely  anni- 
"  hilated  But  neither  of  thefe  fuppofitions  is  true,  iince  out  of  the 
"  wreck  or  ruin  of  one  being  or  exigence,  natures  we  know,  without  an 
"  act  of  creation  or  annihilation,  can  work  up  the  old  materials  into  a 
"  new  fabric. 

"  All  exigences  in  nature  are  referable  to  two  kinds,  I.  Bodies  ; 
"  and,  2.  The  mane^  or  void  in  which  they  exift. 

"  Our  fenfes  fatisfy  us  of  the  exiftence  of  bodies,  as  alfo  do  their 
(i  actions,  paflions,  and  refilling  powers  ;  particularly  as  they  operate 
*s  upon  each  other,  and  upon  our  touch  : 

"  Tangere  enim  et  tangi  nifi  corpus  nulla  poteft  res." — LUCRF/I*. 
"  For  nothing  but  a  body  can  touch  or  be  touched" 

"  From  the  exiftence  and  monon  of  bodies  is  inferred  the  exiftence 
"  of  fpace  ;  and  the  effect  of  bodies  operating  upon  each  other  is  de~ 
<c  nominated  "  an  event  ;'7  and  if  there  was  not  a  'void  there  would  not 
<c  be  a  pofnbllity  of  motion  ;  for  if  a  plenum  exifted,  then  every  portion 
"  of  fpace  being  clofely  impacted  and  wedged  with  folidity,  the  mod 
"  uniform  reft  and  dead  flilnefs  would  pervade  the  whole  of  nature. 

"  As  to  bodies,  they  either  confid  of  elementary  atoms,  or  of  fub- 
"  fiances  formed  from  thefe  ;  and  thefe  primordial  particles,  notwith- 
"  {landing  fome  appearances  to  the  contrary,  are  fimpic,  foiid,  and 
iS  indivifible. 

«  Sunt  igitur  folida,  ac  fine  inani  corpora  prima."— LUCHET, 
"  Therefore  elementary  bodies  are  folid  and  deftitute  of  vacuity.'* 

«  All 


AMERICAN    EDITION.  xix 

4t  All  thefe  atoms  poffefs  the  fame  general  properties,  and  do  not 
.«  differ  from  each  other  in  any  efTential  refpect  Though,  from  their 
.<«  different  operations  upon  the  fenfes,  is  inferred  a  difference  among 
•"  them  as  to  fize,  fhape,  and  heavinefs.  Their  figures,  in  particular, 
i(  are  varied  in  an  endlefs  manner,  fo  as  to  take  on  every  mechanical 
"  form  :  but  in  all  thefe  cafes  they  are  flill  infrangible  and  incapable 
"  of  farther  divifion. 

"  Each  atom  contains,  within  itfelf,  an  active  energy,  or  internal 
"  force,  by  which  it  is  either  conftantly  in  motion,  or  making  an  effort 
"to  move  ;  and  this  is  denominated  gravty  '\  hefe  atoms,  impelled 
"  by  gravity  through  void  Jpace  in  curvilinear  courfes,  ftrike  againft 
<c  each  other,  exercife  repelling  powers,  and  produce  vibration  or  agi- 
"  tation  ;  and  as  this  gravitating  power  is  eTential  to  matter,  it  can 
*c  never  be  inactive,  but  mud  be  always  at  work,  and  has  been  fo  from 
u  eternity. 

"  v.vory  compound  body,  being  made  up  of  individual  atoms  there- 
<c  fore  poifeiTes  the  united  energy  of  them  all,  which  energy  is  thzfole 
"  agent  in  nature  ;  but  by  reafon  of  their  different  figures,  their 
•<f  varied  magnitudes,  and  particular  fituations,  it  is  yarioufly  modifi- 
<l  ed  ;  as  when  the  atoms  are  hooked  or  rough,  motion  will  be  retarded 
(;  among  them,  and  be  facilitated  when  they  are  round  and  fmonth,  as 
"  in  the  principles  of  fire  and  animation.  Bodies  thus  being  eompof- 
"  ed  of  atoms,  derive  their  aaions  from  the  energy  inherent  in  and 
£t  proceeding  from  thefe  atoms 

II  alterations  happening  in  bodies,  whether  in  thtir  fliape,  hard- 
66  nefs,  fweetnefs,  &c.  are  afcnbable  to  the  change  taking  place  in  the 
"  arrangement.  difpofition  £c.  of  the  conftituent  particles  ;  and  thus 
'*  porofky,  tranfparency,  elafticity,  malleability?  &c  are  to  be  account- 
"  ed  for  in  the  fame  way  Gravity  being  an  effential  property  of  mat- 
"  ter,  all  corpufcules,  and  all  bodies  formed  of  them,  mufr  be  heavy. 

"  Thus,  from  thefe  properties  of  bodies,  their  feveral  cnmbinations 
<f  and  mechanical  operations,  arife  other  more  complex  phenomena, 
*.*  referable  however  to  the  principle  of  motion,  fuch  as  the  heating  of 
"  bodies  from  the  influx  of  foft,  round  and  fmooth  particles  ;  the  cool- 
**  ing  of  them  from  the  ingrefs  of  atoms  of  oppolitc  and  irregular 
"  iigures  ;  even  fenfations,  both  of  the  pleafurable  and  painful  kinds, 
"  motion,  reft,  and  time  itfelf,  are  contingences  to  bodies.  In  fliort, 
"  the  whole  phenomena  of  the  production,  growth,  nutrition,  decline, 
"  and  difTolution  of  bodies,  is  to  be  afcribed  to  an  alteration  of  ar- 
4<  rangement  in  the  particles,  and  to  their  addition  or  fubtraction. 

"  Minerals,  plants,  and  animals  were  thus  produced  in  the  beginning, 
"  according  to  thefe  mechanical  laws  of  matter  and  motion,  and  fo  was 
"  the  world  they  compofe  and  inhabit.  They  continue  to  propagate 
"  their  kinds  in  regular  ways,becaufe  nature  has  become  accuftomed,  by 
"  habit,  to  produce  them  in  an  order  fo  uniform  as  to  look  like  rlc/ign. 
*  The  eye,  however,  was  not  made  for  feeing,  nor  the  ear  for  hearing  ; 
"  but  having  been  accidentally  formed  in  fuch  a  way  as  to  anfwer 
£'  thefe  purpofes,  the  fentient  principle  within,  which  is  co-exiilenc 

"  with 


xx  INTRODUCTION  TO  THE 

"  with  tne  organization,  finding  them  fit  for  the  purpofts  of  fight  and 
"  hearing,  makes  ufe  of  them  accordingly. 

"  Senfation,  proceeding  from  the  arrangement  and  texture  of  parti- 
u  cles>  is  to  be  afcribed  to  their  peculiar  magnitude,  fhape,  combina- 
"  tion,  &c.  fo  that  inftead  of  being  an  original  property  of  matter,  it 
"  is.  in  fact,  only  an  occa,fional  quality.  Death  is  the  privation  of 
"  fenfation,  in  confequence  of  the  feparation  of  the  fentient  principle 
"  from  the  body  ;  and  this  femient  principle,  when  a  man  dies,  is  de- 
"  compounded  into  its  fimple  atoms,  lofes  its  fenfitive  powers,  and  goes 
"  into  other  forms  and  combinations,  The  foul,  in  this  refpect,  re- 
"  fembling  the  eye,  which  is  no  longer  capable  of  performing  its  func- 
"  tionsthan  the  connection  of  its  organized  texture  with  the  body  lads/5 

What  ASCLEPIADES  did,  was  to  apply  the  principles  of  the  Epi- 
curean Philofophy  to  medicine,  and  this  he  did  with  much  ingenuity 
and  acutenefs.  Building  upon  that  hypothecs,  he  fuppofed  the  hu- 
man body  compofed  of  Epicurus's  ultimate  atoms,  which,  by  their 
figure,  proximity,  and  arrangement,  enabled  it  to  perform  its  functions  ; 
and  in  a  particular  manner,  that  health  confided  in  the  fymmetry  and 
permeability  of  certain  paffages  through  the  firm  parts,  which  he  calk 
ed  pores  ;  and  the  doling  up,  or  obtlruction  of  thefe,  condituted  dif- 
eafe.  He  imagined  the  fluids  to  be  formed  of  particles,  varying  in 
figure  and  fize.  and  thus  making  all  the  varieties  of  them  from  the 
thickeft  blood  to  the  moil  attenuated  animal  fpirits  And  when  thefe 
fluids  moved  freely  through  their  pores,  the  body  was  found  ;  but  when 
they  were  too  narrow,  fo  as  to  produce  dagnations,  or  fo  oblique  as  not 
to  be  readily  pafTable.  then  indifipofition  enfued. 

Such  were  the  leading  principles  of  ASCLEPIADES,  and  he  had  ma- 
ny followers,  among  whom  THEMISON  of  LAODICEA  was  the  mod 
eminent.  Ke  rejected  mod  of  the  fubtle  and  laboured  reafonings  of 
bis  mailer,  and,  declaring  fuch  minute  invedigations  were  ufelefs,  af- 
firmed, without  defcending  to  particulars,  and  burthening  hirnfelf  with- 
details,  a  phyfician  need  only  make  himfelf  acquainted  with  the  gen- 
eral principles  of  difeafes.  Thefe,  he  faid,  all  belonged  to  two  clafTes. 
i.  Thofe  proceeding  from  laxity  ;  and,  2.  Such  as  were  caufed  by 
Jlriclure.  All  that  was  necelTary  to  be  done,  therefore,  was  to  afcer- 
tain  to  which  clafs  any  given  difeafe  belonged  ;  and  then,  if  to  the 
former,  to  prefcribe  allringsnt  ;  if  to  the  latter,  relaxing  remedies. 

The  regular  and  fyftematic  plan  which  THEMISON  and  his  numer- 
ous followers  adopted  in  their  practice,  differing  very  widely  from  the 
conjectural  and  uncertain  mode  of  other  phyficians,  caufed  them  to  be 
called  METHODISTS  ;  and  they  are  to  this  day  known  in  hiftory  by 
the  name  of  the  METHODIC  SECT.  While  THEMISON  was  reflecting 
upon  his  fyftem,  and  endeavouring  to  advance  it  to  maturity,  he  died, 
and  the  unfinilhed  work  was  taken  up  and  completed  by  his  follower 
THESSALUS.  He  Jived  in  the  time  of  NERO  ;  and  having  reje&ed, 
as  frivolous,  all  the  opinions  of  his  predecefibra,  he  declaimed,  with 
vehemence  and  fury,  againft  the  phyficians  of  all  ages,  and  offered  to 
inftruct  a  beginner  in  the  art  of  medicine  in  the  fhort  duration  of  fix 
months.  And  then,  with  a  degree  of  arrogance  and  impudence,  af 

which, 


AMERICAN  EDITION.  iii 

h,  as  no  parallel  is  known  to  have  exifted  in  ancient  times,  it  can 
only  be  found  in  the  hiftory  of  modern  quackery,  he  took  upon  him- 
klf  the  appellation  of  I«2g«M*ji1pK,  or  the  conqueror  of  phyficians. 

After  THESSALUS  the  feel  began  to  decline  and  dwindle,  and  al- 
though SORANUS,  JULIAN,  and  MOSCHION  retarded  for  a  while  its 
downfal,  yet  it  was  totally  abforbed  and  loft  in  the  Galenic  Doftrines 
which  followed. 

Thus,  from  an  examination  of  the  Methodic  Syjlem,  it  is  evident  the 
explanation  of  every  thing  in  the  animal  economy  is  attempted  upon 

PRINCIPLES  Of    MECHANISM  Only- 

The  firft  notice  of  any  thing  elfe  requifite  to  give  life,  and  regulate 
its  functions,  feems  to  have  occurred  to  HIPPOCRATES,  the  cotempo- 
rary  of  D*.MOCRITUS  and  LEUCIPPUS.  There  tvoffpuv  of  this  faga- 
cious  obferver,  as  the  interpretation  of  the  word  imports,  obvioufly 
means  an  exciting  power  in  animals  :  and  the  effects  of  animation  re- 
fulting  from  this,  imperfectly  known,  and  badly  explained,  doubtlefs 
give  rife  according  to  the  opinion  and  judgment  of  the  different  wri- 
ters, to  the  Nature  of  SvotNHAM,*  the  Aura  Vitalis  of  VAN  HEL- 
MONT,f  the  Vis  naturae  Medicatrix  of  GAUBIUS};(:  the  Anlma  Medica 
of  STAHL  and  NIC  HOLS. $  and  the  learned  and  curious  treatife,  enti- 
tled Impetum  Faciens,  of  KAAUW  BOERHAAVE  || 

And  here  it  is  worthy  of  remark;  that  from  HIPPOCRATES  to 
BROWN,  all  writers  entertain  the  opinion  of  a  principle  or  power  <u>hh- 
in,  exifting  as  the  caufe  of  life,  a°  appears  by  the  active  fignification  of 
all  their  terms  ;  whereas  the  idea  of  the  Brunonians  is,  that  the  or- 
ganized animal  folid  pofTefles  no  internal  energy,  and  would  always  re- 
main inactive,  unlefs  excited  by  itimuli  from  without ;  they  therefore 
fpeak  of  the  vital  capacity  in  the  pa/five  voice,  as  only  fufceptible  of 
being  acted  upon. 

HERMAN  BOERHAAVE,  in  his  account  of  the  difeafes  of  a  lax  and 
of  a  rigid  fibre,  feems  again  to  relapfe  into  the  mechanical  confidcration 
of  thefe  things  ;  but  HALLER,  by  his  numerous  and  luminous  experi- 
ments on  fenlibi'ity  and  irritability,  led  the  way  to  a  right  mode  of 
purfuing  and  underhand  ing  fuch  inquiries. 

The  attention  of  HOFFMAN  had  been  turned  to  the  confideration  of 
the  nervous  fyftem,  as  influencing  difeafes,  more  particular  than  any 
other  perfon  ;  and  from  his  writings  were  probably  taken  the  hints 
which  terminated  in  CULLEN'S  doctrine  of  Excitement  and  Cot/apfe, 
in  his  Phyfiological  Tract  ;^f  enlarged  afterwards,  and  applied  to  prac- 
tice, 

*  Opera  Paflim. 

f  Equidem  fciant  Spiritum  effe  aliquem  illud  imfetwa  faciens  Hippocrates,  vit?e 
davum  manu  fua  tenens  (Ort.  Medicin.p.  724.) 

t  Who  quotes  HIPPOCRATES  for  the  idea  (Sect.  649.)  couched  under  the  term 
*if  av1oKpa.1itoc. 

§  Animam  effe  Gubernatricem,  &c.  &c.     Oratio  de  anima  Medica  pafliin. 

||  Lug.  Batav.  JLutchmans,  1745.  (Chap.  2.) 

*[  Inftitutes  of  Medicine,  §  126  to  135.  "  From  what  has  been  now  faid  of 
the  excitement  and  collapfe  of  the  brain,  it  will  appear  that  we  fuppofe  life,  as  far 
as  it  is  corporeal,  to  confift  in  the  excitement  of  the  nervous  fyftem,  and  efpecially^ 
of  the  brain,  which  unites  the  different  parts,  and  forms  them  into  a  whole5.'" 
§  13.6. 


jteii  INTRODUCTION  TO  THE 

tice,  in  his  chapter  on  vefaniae,  ( Fir  ft  Lines,  §  1544.  and  feq.)  as 
well  as  the  obfervations  in  his  letter  on  the  recovery  of  perfons  drown- 
ed:  (p.  4.)  "  Though  the  circulation  of  the  blood  is  necei7ary  to 
the  fupport  of  life,  the  living  Mate  of  animals  does  not  confifc  in  that 
alone,  but  efpecially  depends  upon  a  certain  condition  of  the  nerves 
and  mufcular  fibres,  by  which  they  are  fenfible  and  irritable,  and  upon 
•which  the  action  of  the  heart  itfelf  depends,"  £c.  Andalfo  the  re- 
marks on  the  effects  of  ftlmuli  in  keeping  up  the  action  and  energy  of 
the  brain*  at  all  times,  in  his  treatife  upon  the  materia  medica. 

JOHN  HUNTER  had  been  fpeculating  too  on  this  fubject.  In  his 
experiments  on  animals,  with  refpect  to  their  power  of  producing 
heat,  he  has  brought  curious  and  important  facts  to  view  :  though 
his  reafoning  on  them  is  in  fome  inftances  inconciuiive  and  exceptiona- 
able,  in  others  quite  unphilofophical.  This  enquiry  was  intended  as  a 
counterpart  to  the  experiments  of  BLAGDEN,  arid  hig  afFociares  in  the 
heated  chamber,  on  the  power  of  the  human  body  to  produce  cold  in 
high  temperatures.  He  afcribes  a  great  deal,  throughout  his  per- 
formance, to  the  ftimulant  action  of  cold,  and  to  the  exhauftion  of 
the  whole  of  the  powers  of  life  in  freezing  animals,  by  their  efforts  to 
produce  heat  ;  he  even  afcribes  the  attempt  of  his  poor  victim,  the 
dormoufe,  to  get  out  of  the  ye/Tel  in  which  he  was  to  be  frozen  to 
death,  to  the  roufing  of  animal  aft  ion  by  cold!  He  feems  to  take  little 
notice  of  the  vital  organs,  the  fire-place  whence  the  conltitution  re- 
ceives its  warmth  ;  nor  regard  much  the  condition  of  the  refpiratory 
function  in  any  of  the  creatures  he  operated  upon,  nor  the  pain  they 
endured,  and  the  changes  in  their  economy  confequent  upon  it.  The 
experiments  on  the  egg,  frog,  eel  and  fnail,  may  be  as  well  explained 
on  the  idea  of  the  increafed  fufceptibility  of  impreflion,  produced  by 
the  fubducticn  of  itimuli,  and  by  an  extraordinary  exertion  of  the 
refpiratory  organs  cauling  a  greater  evolution  of  heat,  as  upon  the 
author's  hypothecs,  which  may  be  fummed  up  in  this  general  con- 
clufion  ;  that  cold  produces  its  effect  in  fufpending  the  voluntary  ac- 
tions, by  acting  as  a  fedatwe  to  a  certain  point ;  beyond  which  it 
feems  to  act  as  ^J^mulant^  exciting  the  animal  powers  to  exert  them- 
felves  for  felf-prefervation. 

It  will  be  evident  to  him  who  reflects  on  what  has  been  related, 
that  the  EPICUREAN  SECTARIES  entertained  no  other  than  mechanical 
notions  concerning  the  production,  actions,  and  changes  of  bodies  ; 
and  that  HIPPOCRATES  and  his  followers,  though  confiderably  more 
advanced  towards  the  truth,  had  gone  no  farther  than  to  obferve  foli- 
tary  and  individual  facts,  arrange  thefe  into  detached  fentences,  or  in- 
fulated  aphorifms,  fometimes  entirely  true,  and  fome  containing  only  a 
mixture  of  truth  ;  or  fiame  flrange  and  whimfical  hypothefes,  by  aid 
of  which,  af>  general  principles,  they  attempted  to  explain  things  ; 
and  the  moft  forward  of  them  feems  to  have  done  little  more  than 
trace  the  corporeal  functions,  by  partial  induction,  to  the  etfaftSkytv. 

XxQoXlMO  Or  COMMON    SENSORY. 

tSuch  was  the  condition  of  medical  fcience,  until  almoft  twenty-five 

year£ 
•*  Materia  Medka,  p.  67,  £c. 


AMERICAN  EDITION. 

years  ago,  when,  in  that  very  place  where  fpafm,  rcaftlon,  and  vis  med- 
Icatrix  nature  were  flourifhing  in  full  vigour,  under  the  afliduous  culti- 
vation of  CULL  EN,  they  were  nipped  and  cropped  in  the  blofTom,  and 
nearly  eradicated  as  noxious,  by  the  improving  hand  of  BROWN. 
From  the  intimate  acquaintance  which  BROWN,  or  BRUNO,  as  he 
called  himfelf,  had  with  the  publifhed  writings,  and  probably  with  the 
private  opinions  of  CULL  EN  ;  from  his  academic  habits,  his  erudition 
and  knowledge  of  every  thing  palling  at  the  Univerfity  of  Edinburgh, 
he  mud  have  had  great  opportunities,  as  well  of  learning  all  that  was 
printed  in  phyfic,  as  of  ftudying  the  defecls,  and  detecting  the  weak- 
Eefs  of  that  profefibr's  doctrines.  He  told  the  writer  of  this  preface, 
that  he  ventured  one  day  to  talk  to  CULLEN  on  the  incomprehenfible 
ideas  of  atony  and  fpafm  exifting  in  the  fame  veflels  of  the  body  at 
the  fame  time  ;  and  thereby  provoked  him  to  manifed  figns  of  impa- 
tience and  difpleafure.  A  coolnefs  took  place  immediately,  which 
increafed  at  lad,  by  fucceflive  and  mutual  aggravations,  to  rooted 
averfion  and  deep  oppofition.  And  to  this  irritated  date  of  BROWN'S 
mind,  indignant  with  the  fenfe  of  unbecoming  treatment,  is  to  be  af- 
cribed  no  fmall  portion  of  that  refolution  and  energy  with  which  he 
laboured  out  a  Sydem  of  Medical  Philofophy,  which,  though  not  free 
from  errors,  borrows,  however,  none  from  CULLEN, 

On  the  publication  and  contents  of  the  fird  edition  of  the  Elementa 
Medicinas  of  this  author  I  mall  be  a  little  particular,  on  account  of 
the  fcarcity  of  the  work,  and  of  the  gratification  it  may  afford  to  an 
enquiring  mind  to  learn  the  progrefs  of  ufeful  difcoveiies. 

It  was  publifhed  in  1780,  and  was  dedicated  to  Sir  JOHN  ELLIOT  ; 
but  this  dedication  was  withheld  from  the  fecond  edition.  After 
dating  his  twenty  years  labour  in  learning  and  teaching  phyfic,  he 
obferves,  it  was  not  until  the  fourth  ludrum  that  fome  dawning  of 
light  broke  in  upon  him. 

.The  opinion  that  in  the  phlegmafias  of  nofologids,  local  afFeclion 
was  not  the  caufe  of  pyrexia,  but  on  the  contrary,  a  fymptom  confe- 
quent  upon  a  previous  general  excitement  of  the  whole  constitution, 
appears  to  have  been  early  adopted  by  him  ;  and  from  his  own  perfon- 
al  fufferings  in  eryfipelas,  cynanche  toniillaris,  catarrh,  and  fynocha, 
and  from  his  perulal  of  whatever  had  been  written  by  MORGAGNI, 
TRILLER,  and  other  candid  authors  on  thefe  fubjecls,  and  on  pneu- 
monia, he  was  confident  his  idea  was  right. 

He,  at  this  time  propofed  the  doclrine  of  ccld  predifpofing  the 
body  to  be  operated  upon  in  a  powerful  manner,  and  to  a  morbid  de- 
gree, by  fubfequent  heat ;  which  indeed  may  be  regarded  as  one  of 
the  mod  important  practical  truths  in  medicine. 

He  calls  in  queition  the  propriety  of  forming  opinions  of  the  nature 
of  difeafes  by  their  fymptoms  merely,  and  boldly  adopts  the  method 
of  judging  from  the  *'  Ixdentia  and  juvantia." 

He  <.fFers  well  founded  criticifm  on  nofological  arrangement,  and 
{hews  wherein,  through  want  of  diitinclion  between  univerfal  and  local 
difeafes,  a  number  of  thefe  had  been  clafTed  wrong. 

On  examining  the  phlogidjc  exanthemata  he  contends,  that   in 

mealies 


INTRODUCTION  TO  THE 

meafles  and  fcarlet  fever,  as  well  as  in  fmall-pox,  the  genera!  indication 
of  cure  is  to  diminifh  the  inflammatory  diathefis,  without  the  leait  re- 
gard to  the  particular  nature  of  the  contagion,  or  the  (rage  of  erup- 
tion ;  but  thefe  are  carefully  to  be  difKnguifhed  from  the  plague,  and 
other  eruptive  difeafes  of  a  totally  oppofite  character  :  and  that  with- 
out attending  to  the  peculiarity  of  the  refpiratinn.  or  the  precife  na- 
ture of  the  morbific  caufe,  the  certain  things  to  be  attended  to  are, 
How  far  the  difeafed  condition  deviates  from  health  ;  and  in  what  de- 
gree the  living  body  approximates  towards  death.  The  exanthema- 
tous  fymptoms  in  the  two  clafles  of  complaints,  varying  in  each,  their 
form  only,  and  not  their  nature. 

Having  proceeded  thus  far,  he  declares  that  difeafes  of  the  fame 
type  or  clafs  are  to  be  relieved,  or  cured  by  the  fame  mode  of  treat- 
ment ;  and  that  the  volumes  of  diagnofHcs,  and  the  endlefs  diftinc- 
tions  of  nofology,  in  fpite  of  the  authority  of  even  BAGLIVI  and  SYD- 
EN  HAM,  when  oppofed  to  clear  reafon  and  matter  of  fact,  ought  to  be 
difregarded.  He  exprefTes  his  appreheniions  too,  left  the  infinite  dif- 
tinction  of  difeafes  mould  lead  to  a  mode  of  practice  equally  diverfi- 
lied,  and  have  a  very  baneful  effect  upon  materia  medica  and  pre- 
fcriptions. 

In  his  remarks  upon  predifpofition  to  bad  health,  he  avers  that  no 
perfon  ever  fudderJy  became  fkk,  but  that  gradually  a  predifpofhioa 
was  created  by  the  agency  of  the  exciting  powers,  and  out  of  this  pre- 
difpoiition  grew  the  difeafe  Of  this  he  gives  examples  in  the  phlogif- 
tic  exanthemata,  wherein  he  fays  a  high  degree  of  excitement  pro- 
duces the  difeafe,  a  lower  predifpofition*  and  a  ftill  lower  health :  the 
means,  therefore,  conducive  to  the  latter  of  thefe  he  thinks  fo  fimple, 
that  the  ufe  of  the  common  nofology  is  inure! y  fuperceded. 

Proceeding  upon  this  plan.,  he  diftinguifhes  local  from  univerfa] 
ailments  ;  both  of  which  are  confufedly  clafied  together,  in  the  differ- 
ent nofological  arrangements 

This  led  him  to  an  examination  of  hemorrhagy,  which,  if  attended 
in  the  beginning  with  phlogtiHc  diathefis.  he  thought  always  became 
eventually  aflhenic,  and  in  this  enquiry  it  was  that  he  was  induced  to 
call  in  queftion  the  exiftence  of  plethora,  as  a  caufe  of  hemorrhagy,  and 
to  reject  altogether  the  notion  of  a  vis  medicatrix  naturse  as  an  agent 
in  the  animal  fyftem. 

This  firft  edition  of  the  Elementa  is  an  unfinimed  work,  and  com- 
prehends the  details  of  his  doctrine  no  farther  than  the  Jlhenic  form  of 
difeafes.  Among  thefe  he  there  ranks  hemorrhagy,  efpecially  menor- 
rhagia,  haemorrhois,  epiihixis,  and  apoplexy  ;  an  arrangement  which 
be  afterwards  confidered  wrong,  and  altered  accordingly  in  the  fol- 
lowing editions  by  placing  them  all  in  the  aflhenic  clafs. 

Such,  he  tells  us,  was  the  train  of  ideas  pailing  in  his  mind  as  hs 
reflected  upon  the  animal  economy ;  and  upon  thefe  confederations 
did  he  judge  himfelf  warranted  in  undertaking  an  explanation  of  the 
fubject,  different  in  many  refpects  from  any  thing  done  before  hi:n. 

He  declares  throughout  the  whole,  he  never  defcends  beneath  hh 
dignity  to  animadvert  Upon  particular  perfons  $  though  in  certain 

cafes,, 


AMERICAN  EDITION.  xxv 

cafes,  where  almoft  implicit  faith  and  idolatrous  reverence  had  been 
given  to  certain  authors,  he  has  freely  attacked  and  refuted  their 
opinions.  He  apologizes  for  the  plainnefs  of  ftyle  and  manner  with 
which  the  performance  is  written,  efpecially,  fince  to  avoid  the  conta- 
gion of  opinion,  he  had  read  no  medical  book  for  five  whole  years, 
and  had  fcarcely  confulted  the  monuments  of  ancient  elegance  for 
twenty. 

There  is  a  great  deal  of  animation  and  force  in  his  argument  againft 
plethora,  from  the  ninety-fourth  to  the  ninety  eighth  fection,  which 
he  concludes  with  this  challenge  :  "  Si  fit  quod  ad  hoc  tefpondeas, 
*'  refponde  STAHLI  aut  jube  JUNCKERUM/'* 

In  the  hundred  and  fourth  fection  he  oppofes,  in  decided  terms,  the 
tonic  or  aftringent  operation  of  cold,  particularly  as  cauiing  conftriction 
of  the  fkin  ;  and  repeats  the  fame  in  feveral  places;  (§  180 — 182.)  de- 
nying that  it  acts  as  a  ftimulant. 

In  his  reafoning  againft  lentor  in  the  fluids  as  a  caufe  of  difeafe,  he 
breaks  out  into  the  following  fpinted  exclamation  :  **  Quam  infelix 
"  ea  pathologia  eft !  cujus  perpetuum  principium,  quod  univerfis 
"  comprehends  partibus  con  venire,  univerfas  illuftrare,  et  explicare 
"  debet,  ne  uni  quidem  convenit,  unam  illuftrat,  unam  explicat,  con- 
"  tra  omnibus  repugnat,  omnes  obfcurat,  et  confundit  ;"  and  reject- 
ing the  pathology  of  the  fluids,  declares,  that  cool  water,  pure  air, 
wine,  and  Peruvian  bark  refift  putrefaction  in  no  other  way  than  by 
keeping  up  excitement. 

In  his  remarks  upon  fpafm,  he  endeavours  to  mew  that  it  cannot  be 
a  caufe  of  difeafe,  either  of  the  fthenic  or  afthenic  kind,  and  ought,  of 
courfe,  to  be  rejected  from  both,  as  mould  alfo  what  has  been  called 
the  reafiion  of  the  fyftem,  in  fever.  In  the  courfe  of  his  animated  ar- 
gument, he  afks  if,  toward  the  end  of  the  eighteenth  century,  "  quis, 
"  opinionem  meram,  nulla  rationis,  nulla  veri  vel  tenuiffima  umbra  com- 
"  mendatam,  folidiilimis  argumentis,  item  ipfi  tuendae  adhibitis  com- 
"  pertam  falfam,  poft  vanam  omni  falfae  logicoe  genere  defenfionem 
"  pro  re  vera  et  certa  oblatum  iri  crederet  ?'' 

He  is  every  where  oppofed  to  that  claflification  and  arrangement  of 
difeafes  which  has  fo  much  obtained  of  late,  and  clofes  this  work  with 
the  words,  "  Nofologia  delenda." 

He  publifhed  a  fecond  edition  in  the  year  1784,  and  added  thereto 
the  afthenic  ciafs  of  difeafes.  Taught  by  experience  and  obfer- 
vation,  in  the  different  forms  of  the  gout  and  althma,  of  the  benefit 
of  ftimulant  remedies,  he  had  no  hefitation  to  confider  them  among  the 
effects  of  weaknefs  ;  as  were  likewife/?!ufr.r  ftriclly  fo  called  (febres) 
both  intermittent  and  continued,  and  all  the  kinds  of  hemorrhagy,  &c. 
In  fhort  the  confideration  of  the  difeafes  not  belonging  to  the  fthen- 
ic clafs,  convinced  him  they  mult  be  referred  to  the  afthenic ;  fuch 
were  all  fpafmodic  or  convulfive  ailments,  dyfpepfia,  and  other  the  like 
affections  of  the  alimentary  canal,  and  the  greater  part  of  the  maladies 
of  children. 

VOL.  L  d  In 

*  Note.   Juncker  was  the  difciple  of  jSthal  and  an  expofitor  of  his  doarine* 


xxv!  iiNTRODUCTION  TO  THE 

In  this  performance  too,  he  contends  again/I  the  advocates  for  fed- 
aiives.  Opium  he  declares,  has  a  ftimulant  operation  ;  colds  or  ca- 
tarrhs are  produced  by  heat  fucceeding  to  cold,  and  not  vice  verfa  ; 
and  extends  his  laws  of  animation  to  the  vegetable  creation. 

In  inert;,  he  concluded  there  was  in  the  medullary  nervous  matter, 
and  mufcular  folid  of  living  bodies,  which  have  been  generally  called 
the  nervous  fyftem,  a  property  by  which  they  could  be  affected  by 
outward  agents,  as  well  as  by  their  own  functions,  in  fuch  a  way  as  to 
produce  the  phenomena  peculiar  to  the  living  flate.  This  capacity  of 
being  acted  upon  is  termed  excitability  ,  and  the  agents  are  ail  denom- 
inated Jlimalants,  while  the  effect  produced  by  the  operation  of  ftimu- 
lants  upon  excitability  is  called  excitement. 

Excitement  i^  terminated  in  two  ways  I.  By  the  exhauftion  of 
excitability,  through  the  violence  or  continuance  of  ftimulus,  which 
is  called  indireft  debility.  2.  By  the  accumulation  of  excitability, 
through  deficient  ftirnulus,  which  is  termed  direft  debility.  Between 
the  two  extremes  of  indirect  and  direct  debility  are  experienced  both 
health  and  difeafes  of  the  fthenic  kind,  or  thofe  febrile  complaints  (py- 
rexise,)  accompanied  with  what  has  been  called  phlogiftic  diatbefis, 
wherein >  though  the  excitement  confiderably  exceeds  the  healthy  rate, 
iHil  it  does  not  reach  the  limits  of  indirect  debility. 

Stimuli  lofe  their  efficacy  after  long  and  frequent  application  ;  but 
even  then  the  excitability,  exhaufted  in  relation  to  one  ftimulus,  is  ca- 
pable of  being  acted  upon  by  another. 

Therefore,  the  wafte  of  excitability,  after  exhauftion  of  one  ftimu- 
lus after  another,  is  very  hard  to  be  repaired,  by  reafon  of  the  difficul- 
ty of  accefs  to  frefh  ftimuli  to  work  upon  the  languifhing  excitability  ; 
which,  by  being  applied  flrong  at  firft*  and  gradually  weakened  after- 
wards, anfwers  the  purpofe  ;  and  alfo  the  fupe? abundant  excitabili- 
ty left  by  fubduction  of  one  ftimulus  after  another,  produces  fuch  an 
excitable  condition  of  the  fyflem,  that  much  nicety  is  requifite  to  wear 
it  gradually  away  by  application  of  very  weak  ftimuli  at  firft,  and  by 
degrees  ftronger  and  ftronger  until  the  accuftomed  ones  can  be  com- 
fortably borne.  According  to  the  Brunonian  Doctrine  difeafes  ap- 
pear under  various  modifications,  as  exhibited  in  the  table  below. 

Thus  they  may  be, 

1.  Univerfal,  fuch  as  primarily  affect  the  whole  confiitution,  as  fe- 
vers, &c. 

2.  Local,  where,  from  limited  morbid   affection,   a  particular  part 
labours,  without  difordering  the  entire  habit;  as  trifling  wounds, 
phlegmons.  &c. 

3    Loco-uriiverfal,   when,   from  a  local  affection,  the  whole  body  is 
eventually  brought  into  a  di&afed  condition  ;  as  in  lues  originat- 
ing from  chancre,  fnpall-pox  from  inoculation,  &c 
4.  Univerfo  local  ;  as  if,  after  a  general  ailment  any  particular  part 
or  organ  is  affected  in  a  fecondary  way  ;  as  the  eruptions  of  exan- 
thematous  pyrexks,  fyphilitic  blotches,  &c. 
And  each  of  thefe  forms  of  difeafes  muft  confift  either  in, 
Diredt  debility  ;  as  in  fcurvy,  hunger,  cold,  £c, 

2.  Sihenic 


AMERICAN  EDITION.  xxvii 

2.  Sthenic  diathefis  ;  as  in  pleurify,  other  forms  of  fynocha,  &c. 

3.  Indirect  debility  ;  as  in  old  age,  intoxication,  fatigue    &c. 

4.  Direct  debility  added  to  indirect  ;  as  in  gout  very  often,  and  in 
many  difeafes  of  advanced  life. 

5.  Indirect  debility  added  to  direct  ;   as  in  over-feeding  a  famifhed 
perfon,  &a  in  mod  difeafes  of  infants  and  young  perfcns 

Let  now  the  candid  reader  compare  this  view  with  the  opinions  of 
the  old  METHODISTS,  and  fay  whether  it  be  a  mere  revival  of  the 
practice  of  TH  EMI  SON,  and  THFSSALUS  ?  Surely  they  who  have  af- 
ferted  it  was,  can  never  be  fuppofed  to  have  given  themfelves  the  trou- 
ble to  examine. 

Yet,  with  all  this  novelty  about  it,  BROWN'S  doctrine  wants  pre- 
cifion.  It  proceeds  not  far  enough  beyond  general  principles,  which,  by 
reafon  of  their  abftract  or  fpeculative  nature,  have  not  been  found  clofely 
enough  applicable  to  the  fubjects  of  pathology  and  phyfiology.  He  takes 
for  granted,  for  inftance,  that  tru  nervous  fyftem  is  always  one  and 
the  fame  excitable  thing.  He  fays  fcarcely  any  thing  accurate  on  the 
different  qualities  of  the  blood  and  circulating  fluids,  and  of  the  fecre- 
tions  ;  and  gives  nothing  very  minute  concerning  the  mighty  influence 
of  the  refpiratory  and  digeftive  procefTes  upon  the  animal  economy. 
He  paiTes  over  entirely  the  chemical  compofition  of  our  food  and 
drink,  of  our  inhalations  and  excretions  of  the  gafes  we  breathe  and 
the  remedies  we  fwallow :  in  fhort,  he  has  left  not  a  fentence  on  the 
compofition  or  the  nature  of  bone,  mufcle,  vefTel,  fat,  lymph,  or 
gluten,  nor  how  varioufly  thefe  are  arTefted  by  difeafe,  nor  in  what 
their  healthy  differs  from  their  morbid  fhte,  nor  by  what  means  the 
alterations  they  undergo  are  brought  about. 

Thefe,  and  other  omiilions  and  defects  in  the  BRUNONIAN  SYSTEM, 
called  lor  amendment  ;  and  this  was  to  be  begun  by  attending  to  the 
varying  condition  of  the  living  folid,  and  the  concomitant  (late  of  the 
fluids. 

The  eftablifhment  of  the  new  nomenclature  of  chemiftry  in  France, 
in  1787,  maybe  confidered  as  forming  a  new  epoch  in  fcience.  Since 
the  publication  of  that  invaluable  performance,  language  has  been 
adapted  with  greater  accuracy  to  the  expreffion  of  ideas,  and  philo- 
fophical  inveftigation  conducted  with  fuperior  advantage  and  fuccefs. 
LAVOISIER,  in  his  Elements  of  Chemifrry,  has  attempted  the  expla- 
nation of  the  putrefactive,  as  well  as  the  fermentative  procefs  in  the 
organized  forms  of  animals  and  of  plants,  upon  the  modern  principles  ; 
and,  in  a  natural  and  convincing  manner,  has  proceeded  a  great  way 
beyond  any  one  who  undertook  the  explanation  before.  SPALLAN- 
ZANI,  indeed,  in  his  Experiments  on  the  Concoction  of  Food  in 
the  Stomach,  and  CRAWFORD,  in  his  Application  of  the  Principles  of 
CornbufKon  to  the  Function  of  the  Lungs  in  breathing,  had  given  ex- 
cellent fpecimens  of  this  mode  of  reafoning  on  phyfiologicai  fubjects. 
Great  progrefs  has  been  made  fince  in  detecting  the  nature  and  prop- 
erties of  the  atmofphere,  the  gafes  and  ceiiform  fluids  ;  and  the  right 
knowledge  of  thefe,  derived  from  experiment  and  obfei  vation,  has  fur- 

niihed 


INTRODUCTION  TO  THE 

milled  the  means  of  expounding  many  of  the  animal  fun&ionS,  in  a 
plain  and  happy  manner. 

We  do  not  merely  know,  at  prefent,  that  there  is  a  gafeous  produc- 
tion, purs  air,  necefTary  to  the  prefervation  and  continuance  of  animal 
life  ;  but  we  think  \ve  know  it  is  a  compound  fubftance,  and  what  its 
compound  ingredients  are  ;  we  believe  we  can  make  and  unmake  it  ar- 
tificially, ard  that  nature  is  doing  fo  inceflantly  :  we  think  the  term 
"  deplogifticated  air"  not  accurately  nor  logically  applied  ;  but, 
judging  from  its  tendency  to  produce  fournefs  when  combined  with 
other  bodies,  we  call  the  bads  of  it  "  the  acidifying  principle,"  and 
the  combination  of  that  bafe  with  light  and  caloric  or  the  matter  of 
heat,  <4  oxygene  gas  or  air,"  or  more  properly  "  gafeous  oxyd  of  light." 

From  noting  the  operation  of  this  oxygene  or  principle  of  fouring, 
upon  various  bodies,  we  imagine  we  know  the  compofition  of  acids  ^  and 
hare  made  out  a  confiderable  'ift  of  acidifiable  bafes  ;  fo  that  the  forma- 
tion of  fixed  air,  from  oxygene  and  carbone,  or  charcoal,  of  nitrous  acid 
from  it  and  azote,  of  vitriolic  acid  from  the  fame  and  fulphur,  and  phof- 
phoric  acid  from  its  union  with  phofphorus,  feem  to  be  well  eftablifh- 
ed  truths.  We  imagine  that  a  certain  other  clafs  of  bodies  capable  of 
combining  with  oxygene,  but  not  to  the  point  of  acidity,  forms  there- 
by half-acids  or  oxyds,  and  that  thus  the  calces  of  metals,  animal 
blood  and  fecretions,  as  well  as  the  farinaceous,  gummy,  and  mucil- 
aginous parts  of  phnts,  are  formed. 

We  think  the  competition  of  water  is  underftood,  and  inftead  of  be- 
ing an  elementary  body,  as  was  formerly  believed*  that  it  is,  in  fact, 
but  the  oxyde  of  hydrogene,  or  a  combination  of  this  latter  fubftance 
with  the  principle  of  acidity,  but  not  the  fouring  point. 

It  is  confidered  alfo,  that  more  is  known  concerning  the  compofition 
of  the  irritable  fibre,  of  the  adipoie  matter,  and  of  the  bones  :  and  that 
the  effects  produced  upon  the  circulated  fluids  by  breathing,  and 
through  them  upon  the  folids  cf  the  animal  body  in  health,  and  the 
alterations  too  that  the  liquid  and  firm  parts  undergo  by  impeding, 
'vitiating,  or  ob(lru#ing  that  function,  in  ordinary  cafes,  as  well  as 
in  gravid  females,  are  now  better  comprehended  than  they  ufed  to  be. 
Inafnmch,  that  after  the  great  light  thrown  upon  this  fubject,  fucceed- 
ing  authors  have  been  enabled  to  drefs  up  the  Brunonian  Syttem  in 
the  more  recent  faihion,  and  to  fupply  and  adorn  it  with  almoft  all 
that  was  wanting  to  make  it  additionally  engaging  and  attrac- 
tive. Drowning,  fuffocation,  fcurvy,  ftone,  dyfentery,  peftilence,  ulcers 
and  fever,  have  already  received  great  elucidation,  both  in  theory  and 
practice,  from  the  application  of  chemical  principles  ;  and  we  may 
reafonably  hope,  that  before  many  more  years  elapfe,  better  and  more 
correct  ideas  will  be  entertained  of  many  articles  of  the  materia  medica> 
and  of  their  manner  of  c  perating  ;  that  a  new  medical  nomenclature 
(than  which  nothing  in  fcience  is  more  wanting)  will  be  made  out  ; 
and  that,  from  the  afcertained  condition  of  the  body,  and  the  known 
compofition  and  operation  of  remedies,  phyficians  may  prefcribe  fairly 
for  the  actual  it  ate  of  the  conflitution,  and  the  removal  of  the  prefent 

malady, 


AMERICAN  EDITION. 

aialady»  without  being  mifled  as  too  often  happens  at  prefent,  by  fpe- 
cious  words,  and  idle  or  deceitful  names 

But,  notwithftanding  the  many  and  beautiful  applications  of  chem- 
ical principles  to  the  explanation  of  the  animal  functions,  we  are  not  to 
imagine  any  thing  in  life  fufceptible  of  chemical  interpretation. 
What  it  is  that  enables  the  atoms  compofing  a  mufcle  to  cohere,  and 
the  mufcle  to  contract  and  perform  great  exertions  of  (trength,  we 
know  not ;  but  this  we  know  very  well,  that  we  can  never  form  a  muf- 
cle by  fynthefis,  or  the  putting  together,  in  any  artificial  form,  thofe 
fubflances  which  appear,  from  analyfis  to  conftitute  a  mufcle.  There 
is  fomething  in  animated  exiftence»  which  eludes  our  moft  active  re* 
fearches,  and  which  defies  fubmiffion  to  either  mechanical  or  chemical 
laws.  With  refpect  to,  chemical  modes  of  reafoning  upon  thefe  fub- 
jects,  it  is  obfervable,  that  they  apply,  with  their  greatefl  extent  and 
accuracy,  to  fuch  parts  of  the  body  as  have  the  lowest  degree  of  ani- 
mation, as  the  contents  of  the  inteftines,  teeth,  bones,  fat,  fubflan- 
ces adhering  to  the  {kin,  and,  generally  fpeaking,  the  circulated  and 
fecreteu  fluids  ;  while  the  qualities  of  mufcular  fibres,  by  which  they 
become  contractile,  and  of  nervous  expanfions,  whereby  they  take  on 
fenfation,  with  the  whole  of  the  functions  arifing  from  irritability  and 
fenfibility,  are  referable  to  other  and  different  laws. 

The  invefttgation  of  thefe  Laws  of  Organic  Life  is  attempted  by 
our  learned  and  very  ingenious  author  in  the  following  work.  The 
Zoonomia,  therefore,  though  not  exempt  from  fanciful  and  viflonary 
doctrines,  piefents  coniiderations  of  the  firfl  importance,  both  to  the 
fpecuiative  philofopher  and  the  practical  phyfkian  ;  to  him  who  con- 
templates the  operations  of  mind  as  a  fcience,  or  to  him  that  attends 
to  the  corporeal  functions  as  an  artifi  The  fecond  part  of  this  work 
being  engaged  in  an  arrangement  of  difeafes,  with  their  remedies  and 
modes  of  treatment,  will  be  very  acceptable  to  the  practical  as  well  as 
the  theoretical  phyfician.  After  the  different  projects  for  methodiz- 
ing this  department  of  knowledge,  which  have  fucceffively  been  offer- 
ed to  the  public  with  fo  little  advancement  of  true  fcience,  the  friends 
of  medical  improvement  and  of  the  healing  art  will  joyfully  accept 
of  fomething  that  promifes  to  lead  them  from  arbitrary  fyflem  to  nat- 
ural method.  And  as  the  diitinctions  are  founded  upon  the  increafed^ 
decreafed  or  inverted  actions  of  the  moving  machinery  of  the  body,  it 
will  inflantly  be  perceived  how  clofely  the  Brunonian  doctrine  is  inter- 
woven with  the  whole  fubject.  It  is  however  to  be  always  borne  in 
mind  that  on  American  difeafes  the  phyficians  of  this  country  have 
generally  written  the  beft. 

SAMUEL  L.  MITCHELL. 
New-Tori,  Nov.  3,  1802, 


ZOONOMIA  ; 


OR 


THE    LAWS    OF    ORGANIC    LIFE. 
PART  i. 


CONTAINING 


THE  IMMEDIATE  CAUSES  OF  ANIMAL  MOTIONS, 


DEDUCED     FROM 

THEIR  MORE  SIMPLE  OR  FREQUENT  APPEARANCES  IN  HEALTH ; 

AND    APPLIED    TO    EXPLAIN 

THEIR  MORE  INTRICATE  OR  UNCOMMON  OCCURRENCES 
IN  DISEASES. 


QUI    POTUJT    RERUM    COGNO8CERE    CA-US.AS. 


r 


ZOONOMIA. 


SECT.   .  I. 


or  MOTION. 


THE  WHOLE  OF  NATURE  may  be  fuppofed  to  confift  of  two 
eflences  or  fubftances  ;  one  of  which  may  be  termed 
ipint,  and  the  other  matter.  The  former  of  thefe  poflrffes  the 
power  to  commence  or  produce  motion,  arid  the  latter  to  receive 
and  communicate  it.  So  that  motion,  confidered  as  a  caufe,  im- 
mediately precedes  every  effect  ;  and  confidered  as  an  effect,  it 
immediately  fucceeds  every  caufe.  And  the  laws  of  motion 
therefore  are  the  laws  of  nature. 

The  MOTIONS  OF  MA  i  TER  may  be  divided  into  two  kinds, 
primary  and  fecondary  The  fecondary  motions  are  rhofe,  which 
are  given  to  or  received  from  other  matter  in  motion.  Their 
laws  have  been  fucceisfuily  inveftigaled  by  philofophers  in  their 
treatifes  on  mechanic  powers.  Thefe  motions  are  diftinguifhed 
by  this  circmuftance,  that  the  velocity  multiplied  into  the  quan- 
tity of  matter  of  the  body  acted  upon  is  equal  to  the  velocity 
multiplied  into  the  quantity  of  matter  of  the  acting  body. 

The  primary  motions  of  matter  may  be  divided  into  three 
clafles,  thofe  belonging  to  gravitation,  to  chemiflry,  and  to  life  j 
and  each  clafs  has  its  peculiar  laws.  Though  thefe  three  clafles 
include  the  motions  of  folid,  liquid,  and  aerial  bodies  ;  there  i£ 
neverthelefs  a  fourth  divifion  of  motions  ;  I  mean  thofe  of  the 
fuppofed  ethereal  fluids  of  magnetifm,  electricity,  heat,  and 
light  ;  whofe  properties  are  not  fo  well  inveftigated  as  to  be 
clafled  with  fufEcient  accuracy. 

\ft.  The  gravitating  motions  include  the  annual  and  diurnal 
rotation  of  the  earth  and  planets,  the  flux  and  reflux  of  the 
ocean,  the  defcent  of  heavy  bodies,  and  other  phenomena  of 
gravitation.  The  unparalleled  fagacity  of  the  great  NEWTON 
has  deduced  the  laws  of  this  claG  of  motions  from  the  firnple 
principle  of  the  general  attraction  of  matter  :  to  which  ihouid 
perhaps  be  added  the  general  repul/ion  of  matter  ;  which  feems 

VOL.  I.  B  to 


2  OF  MOTION.  SECT.  I. 

to  have  caufed  the  proje&ion  of  the  planets  from  the  fun,  and 
to  prevent  their  relapfe  into  one  chaotic  mafs.  Thefe  motions 
are  diftin^uifhed  by  their  tendency  to  or  from  the  centres  of  the 
fun  or  planets. 

id.  The  chemical  clafs  of  motions  includes  all  the  various  ap- 
pearances of  chemiftry.  Many  of  the  fads,  which  belong  to 
thefe  branches  of  fcience,  are  nicely  afcertained,  and  elegantly 
clafled  ;  but  their  laws  have  not  yet  been  developed  from  fuch 
fimple  principles  as  thofe  above  mentioned  ;  though  it  is  prob- 
able, that  they  depend  on  the  fpecific  attractions  belonging  to 
the  particles  of  bodies,  or  to  the  difference  of  the  quantity  of  at- 
traction  belonging  to  the  fides  and  angles  of  thofe  particles,  to 
which  (hould  perhaps  be  added  the  fpecific  repulfions  belonging 
to  the  particles  of  bodies.  When  thefe  repulfions  prevail  over 
the  attractions,  they  may  caufe  the  diffufions  of  light  and  of 
odours,  the  explofions  of  fome  bodies,  and  the  flower  decompo- 
fition  of  others,  and  occafion  our  ideas  of  fluidity  ;  when  the 
attractions  prevail  over  the  repulfions,  they  may  caufe  the  drift- 
er combinations  and  cohefions  of  matter,  as  in  cryftallization  or 
cooling,  and  give  rife  to  our  ideas  of  folidity  ;  and  when  thefe 
two  caufes  of  motion  are  in  a&ive  equilibrium,  they  may  pro- 
duce the  vibrations  of  the  particles  of  bodies,  and  occafion  our 
ideas  of  found.  The  chemical  motions  are  diftinguifned  by  their 
being  generally  attended  with  an  evident  decompofition  or  new 
combination  of  theaftive  materials. 

3 d.  The  third  clafs  includes  all  the  motions  of  the  animal  and 
vegetable  world  ;  as  well  thofe  of  the  veflels,  which  circulate 
their  juices  and  of  the  mufcles,  which  perform  their  locomotion, 
as  thofe  of  the  organs  of  fenfe,  which  conflitute  their  ideas. 

This  laft  clafs  of  motion  is  the  fubjeft  of  the  following  pages ; 
which,  though  confcious  of  their  many  imperfections,  I  hope 
may  give  fome  pleafure  to  the  patient  reader,  and  contribute 
fomething  to  the  knowledge  and  to  the  cure  of  difeafes. 

SECT. 


SECT.  II.  i.  i.  DEFINITIONS.  3 

SECT.      II.      i. 

EXPLANATIONS    AND    DEFINITIONS. 

I.  Outline  of  the  animal  economy. — II.  i.  Of  the  fenforium.  2. 
Of  the  brain  and  nervous  medulla.  3.  A  nerve.  4.  A  mufcu- 
lar  fibre.  5.  The  immediate  organs  offenfe.  6.  The  external 
organs  of  fenfe.  7.  An  idea  or  fenfual  motion.  8.  Perception. 
9.  Senfation.  10.  Recolleflion  andfuggejlion  II.  Habit >  cauja*- 
tion,  ajficiation,  catenation.  \  2.  Reflex  ideas.  1 3 .  Stimulus  dejined. 


As  fome  explanations  and  definitions  will  be  neceflary  in  the  profecu- 
tion  of"  the  work,  the  reader  is  troubled  with  them  in  this  place,  and 
is  intreated  to  keep  them  in  his  mind  as  he  proceeds,  and  to  take 
them  for  granted,  till  an  apt  opportunity  occurs  to  evince  their  truth  ; 
to  which  1  ihall  premifeavery  ihort  outline  of  the  animal  economy. 


I. — i.  THE  nervous  fyftem  has  its  origin  from  the  brain,  and 
is  diftributed  to  every  part  of  the  body.  Thofc  nerves,  which 
ferve  the  fenfes,  principally  arife  from  that  part  of  the  brain, 
which  is  lodged  in  the  head  ;  and  thofe,  which  ferve  the  pur- 
pofes  of  mufcular  motion,  principally  arife  from  that  part  of  the 
brain,  which  is  lodged  in  the  neck  and  back,  and  which  is  erro- 
neoufly  called  the  fpinal  marrow.  The  ultimate  fibrils  of  thefc 
nerves  terminate  in  the  immediate  organs  of  fenfe  and  mufcular 
fibres,  and  if  a  ligature  be  put  on  any  part  of  their  pillage  from 
the  head  or  fpine,  all  motion  and  perception  ceafe  in  the  parts 
beneath  the  ligature. 

2.  The  longitudinal  mufcular  fibres  compofe  the  locomotive 
mufcles,  whofe  contractions  move  the  bones  of  the  limbs   and 
trunk,  to  which  their  extremities  are  attached.     The  annular  or 
fpiral  mufcular  fibres  compofe  the  vafcular  mufcles,  which  con- 
ftitute  the  inteftinal  canal,  the  arteries,   veins,    glands,   and  ab- 
forbent  veflels. 

3.  The  immediate  organs  offenfe,    as  the  retina  of  the  eye, 
probably  confift  of  moving  fibrils,  with  a  power  of  contraction 
fimilar  to  that  of  the  larger  mufcles  above  defcribed. 

4.  The  cellular  membrane  confifts   of  cells,  which  refemble 
thofe  of  a  fponge,   communicating  with  each  other,   and   con- 
necting together  all  the  other  parts  of  the  body. 

5.  The  arterial  fyftem  confifts  of  the  aorta  and  the  pulmona- 
ry artery,    which  are  attended  through  their  whole  courfe  with 

their 


4  DEFINITIONS.  SECT.  II.  i.  6. 

their  correfpondent  veins.  The  pulmonary  artery  receives  the 
blood  from  the  right  chamber  of  the  heart,  and  carries  it  to  the 
minuce  extenfive  ramifications  of  the  lungs,  where  it  is  expoied 
to  the  a&ion  of  the  air  on  a  furface  equal  to  that  of  the  whole 
external  fkin,  through  the  thin  moift  coats  of  thofe  veiTels,  which 
are  fpread  on  the  air-cells,  which  conftitute  the  minute  terminal 
ramifications  of  the  wind-pipe.  Here  the  blood  changes  its 
colour  from  a  dark  red  to  a  bright  fcarlet.  It  is  then  collected 
by  the  branches  of  the  pulmonary  vein,  and  conveyed  to  the 
left  chamber  of  the  heart. 

6.  The  aorta  is  another  large  artery,  which  receives  the  blood 
from  the  left  chamber  of  the  heart,  after  it  has  been  thus  aera- 
ted in  the  iungs,  and  conveys  it  by  afcending  and  defcending 
branches  to  every  part  of  the  fyftem  ;  the  extremities  of  this  ar- 
tery terminate  either  in  glands,  as  the  falivary  glands,  lachrymal 
glands,  &c.  or  in  capillary  veflels,  which  are  probably  lefs  invo- 
luted glands ;  in  thefe  fome  fluid,  as  falva,  tears,  perfpiration,  is 
fe^arateu  from  the  blood  j  and  the  remainder  of  the  blood  is 
abiorbed  or  drank  up  by  branches  of  veins  correfpondent  to  the 
branches  of  the  artery  ;  which  are  furnifhed  with  valves  to  prevent 
its  return  ;  and  is  thus  carried  back,  after  having  again  changed 
its  colour  to  a  dark  red,  to  the  right  chamber  of  the  heart.  The 
circulation  of  the  blood  in  the  liver  differs  from  this  general  fyf- 
tem ;  for  the  veins  which  drink  up  the  refluent  blood  from  thofc 
arteries,  which  fpread  on  the  bowels  and  mefentery,  unite  into 
a  trunk  in  the  liver,  and  form  a  kind  of  artery  which  is  branch- 
ed into  the  whole  fubftance  of  the  liver,  and  is  called  the  vena 
portarum  5  and  from  which  the  bile  is  feparated  by  the  numer- 
ous hepatic  glands,  which  conftitute  that  vifcus. 

7.  The  glands  may  be  divided  into  three  fyftems,  the  convo- 
luted glands,  fuch  as  thofe  above  defcribed,  which  feparate  bile, 
tears,  faliva,  £c.  Secondly,  the  glands  without  convolution,  as 
the  capillary  veflels,  which  unite  the  terminations  of  the  arteries 
and  veins  and  feparate  both  the  mucus,  which  lubricates  the  cel- 
lular membrane,  and  the  perfpirable  matter,  which  preferves  the 
fkin  moift  and  flexible.  And  thirdly,  the  whole  abforbent  fyftem, 
confiding  of  the  ladeals,  which  open  their  mouths  into  the  ftom- 
ach  arid  inteftines,andof  the  lymphatics,  whichopen  their  mouths 
on  the  external  furface  of  the  body,  and  on  the  internal  linings  of  all 
the  cells  of  the  cellular  membrane,  and  other  cavities  of  the  body. 
Thefe  lacteal  and  lymphatic  veflels  are  furnifhed  with  nu- 
merous valves  to  prevent  the  return  of  the  fluids,  which  they 
abforb,  and  terminate  in  glands  called  lymphatic  glands,  and 
may  hence  be  confidered  as  long  necks  or  mouths  belonging  to, 
thefe  glands.  To  thefe  they  convey  the  chyle  and  mucus,  with 


SECT.  II.  i.  *.  DEFINITIONS.  5 

a  part  of  the  perfpirable  matter,  and  atmofpheric  moifture  ;  all 
which  after  having  patted  through  thefe  glands,  and  having 
fuffered  fome  change  in  them,  are  carried  forward  into  the 
blood,  and  fupply  perpetual  nourifhment  to  the  fyftem,  or  re- 
place its  hourly  wafte. 

8.  The  ftomach  and  inteftinal  canal  have  a  conflant  vermic- 
ular motion,  which  carries  forward  their  contents,  after  the 
lacteals  have  drank  up  the  chyle  from  them  ;  and  which  is  ex- 
cited into  adion  by  the  ftimulus  of  the  aliment  we  fwallow,  but 
which  becomes  occafionally  inverted  or  retrograde,  as  in  vomit- 
ing, and  in  the  iliac  paflion. 

II.  I.  The  word  fenforium  in  the  following  pages  is  defign- 
ed  to  exprefs  not  only  the  medullary  part  of  the  brain,  fpinal 
marrow,  nerves,  organs  of  fenfe  and  of  the  mulcles ;  but  alfo 
at  the  fame  time  that  living  principle,  or  fpirit  of  animation, 
which  refides  throughout  the  body,  without  being  cognizable  to 
our  fenfes,  except  by  its  effects.  The  changes  which  occafion- 
ally take  place  in  the  fenforium,  as  during  the  exertions  of  voli- 
tion, or  the  fenfations  of  pleafure  or  pain,  are  termed  fenforial 
motions. 

2.  The  fimilarity  of  the   texture  of  the  brain  to   that  of  the 
pancreas,  and  fome  other  glands  of  the  body,  has  induced  the 
inquirers  into  this  fubjed  to  believe,  that  a  fluid,  perhaps  much 
more  fubtile  than  the  eledric  aura,  is  feparated   from  the  blood 
by  that  organ  for  the  purpofes  of  motion  and  fenfation.     When 
we  recollc-d,  that  the  eledric  fluid  itfelf  is  adually  accumulated 
and  given  out  voluntarily  by  the  ^orpedo  and  the  gymnotus  elec- 
tricus,  that  an  eledric  (hock  will  frequently  ftimulate  into  mo- 
tion a  paralytic  limb,  and  laftly  that  it  needs  no  perceptible  tubes 
to  convey  it,  this  opinion  feems  not  without  probability  ;  and 
the  fmgular  figure  of  the  brain  and  nervous  fyftem  feems  well 
adapted  to  diftribute  it  over  every  part  of  the  body. 

For  the  medullary  fubitance  of  the  brain  not  only  occupies 
the  cavities  of  the  head  and  fpine,  but  paifes  along  the  innumer- 
able ramifications  of  the  nerves  to  the  various  mufcles  and  or- 
gans of  fenfe.  In  thefe  it  lays  afide  its  coverings,  and  is  inter- 
mixed with  the  flcnder  fibres,  which  conftitute  thofe  mufcles 
and  organs  of  fenfe.  Thus  all  thefe  diitant  ramifications  of  the 
fenforium  are  united  at  one  of  their  extremities,  that  is,  in  the 
head  and  fpine  \  and  thus  thefe  central  parts  of  the  fenforium 
conftitute  a  communication  between  all  the  organs  of  fenfe  and 
mufcles. 

3.  A  nerve  is  a  continuation  of  the  medullary  fubftance  of 
the  brain  from  the  head  or  fpine  towards  the  other  parts  of  the 
body,  wrapped  in  its  proper  membrane. 

4.  The 


6  DEFINITIONS.  SECT.  II.  2. 4, 

4.  The  mufcular  fibres  are  moving  organs  intermixed  with  that 
medullary  fubftance,  which  is  continued  along  the    nerves,  as 
mentioned  above.     They  are  indued  with  the  power  of  contrac- 
tion, and  are  again  elongated  either   by  antagonift  mufcles,  by 
circulating  fluids,  or  by   elaftic  ligaments.     So  the  mufcles  on 
one  fide  of  the  fore-arm  bend  the  fingers  by  means  of  their  ten- 
dons, and  thofe  on  the  other  fide  of  the  fore-arm  extend  them 
again.     The    arteries  are  diftended  by   the  circulating  blood  ; 
and  in  the  necks  of  quadrupeds  there  is  a  ftrong  elaftic    liga- 
ment,  which  affifts  the  mufcles  which  elevate  the  head,  to  keep 
it  in  its  horizontal  pofition,  and  to  raife  it  after  it  has  been  de- 
prefTed. 

5.  The   immediate  organs  of  fenfe  confift  in  like  manner  of 
moving  fibres  enveloped  in  the  medullary  fubftance  above  men- 
tioned ;  and  are  erroneoufly  fuppofed  to  be  fimply  an  expanfion 
of  the  nervous  medulla,  as  the  retina  of  the  eye,  and  the  retc 
mucofum  of  the  fkin,  which  are  the  immediate  organs  of  vifion, 
and  of  touch.     Hence  when  we  fpeak  of  the  contractions  of  the 
fibrous  parts  of  the  body,  we  fhall  mean  both   the  contractions 
of  the   mufcles,  and   thofe  of  the  immediate    organs  of   fenfe. 
Thefe  fibrous  motions  are   thus  diftinguimed  from  the  fenforial 
motions  above  mentioned. 

6.  The  external  organs  of  fenfe  are  the  coverings  of  the    im- 
mediate organs  of  fenfe,  and  are  mechanically  adapted  for  the 
reception  or  tranfmiffion  of  peculiar   bodies,  or  their  qualities, 
as  the  cornea  and  humours  of  the  eye,  the  tympanum  of  the  ear, 
the  cuticle  of  the  fingers  and  tongue. 

7.  The  word  idea  has  various   meanings   in  the  writers  of 
metaphyfic  :  it  is  here  ufed  fimply  for  thofe   notions  of  external 
things,  which  our  organs  of  fenfe  bring  us  acquainted  with  orig- 
inally ;  and  is  defined  a  contraction,  or  motion,  or  configuration, 
of  the  fibres,  which  conftitute  the  immediate  organ  of  fenfe  j 
which   will  be  explained  at   large  in  another  part  of  the  work. 
Synonymous  with  the  word  idea,    we  (hall   fometimes  ufe  the 
words  fenfual  motion  in  contradiftinction  to  mnfculat  motion. 

8.  The  word  perception  includes  both  the  adlion  of  thj^prgan 
of  fenfe  in  confequence   of  the  impact  of  external  objefts,  and 
our  attention  to  that  action  ;  that  is,  it  exprefTes  both  thq  motion 
of  the  organ  of  fenfe,  or  idea,  and  the  pain  or  pleafure  that  fuc- 
ceeds  or  accompanies  it. 

9.  The  pleafure  or  pain  which   neceflarily  accompanies  all 
thofe  perceptions  or  ideas  which  we  attend  to,  either  gradually 
fubfides,  or  is  fucceeded  by  other  fibrous  motions.     In  the  latter 
cafe  it  is  termed  fenfation^  as  explained  in  Se£t.  V.  2,  and  VI. 
2. — The  reader   is  intreated   to  keep  this  in  his  mind,   that 

through 


SECT.  II.  2.  10.          DEFINITIONS. 

through  all  this  treatife  the  word  fenfation  is  ufed  to  exprefs 
pleafure  or  pain  only  in  its  aftive  ftate,  by  whatever  means  it  is 
introduced  into  the  fyftem,  without  any  reference  to  the  ftimu- 
lation  of  external  objects. 

10.  The  vulgar  ufe  of  the    word  memory  is  too  unlimited  for 
our  purpofe  :  thofe  ideas   which  we  voluntarily  recal  are  here 
termed  ideas  of  recolleElion^  as  when  we  will  to  repeat  the  alpha* 
bet  backwards.     And  thofe  ideas  which  are  fuggefted  to  us  by 
preceding  ideas  are  here  termed  ideas  oifuggcflion^  as  whilft  we 
repeat  the  alphabet  in  the  ufual  order  ;    when  by  habits  previ- 
oufly  acquired  B  is  fuggefted  by  A,  and  C  by  B,  without  any 
effort  of  deliberation. 

11.  The   word  aflbciation  properly  fignifies  a  fociety  or  con- 
vention of  things  in  fome  refpects  fimilar  to  each  other.     We 
never  fay  in  common  language,  that  the  effe6t  is  aflbciated  with 
the  caufe,   though  they  neceflarily  accompany  or  fucceed  each 
other.     Thus  the   contractions  of  our   mufcles  and  organs   of 
fenfe  may  be  faid  to  be  aflbciated  together,  but  cannot  with  pro- 
priety be  faid  to  be  aflbciated  with  irritations,  or  with  volition, 
or  with  fenfation  ;  becaufe   they  are  caufed  by    them,  as  men- 
tioned in  Sed.  IV.     When  fibrous  contractions  fucceed  other 
fibrous  contractions,  the  connexion  is  termed  affociation  ;  when 
fibrous   contractions   fucceed  fenforial  motions,  the  connection 
is  termed  caufation  ;  when  fibrous  and  fenforial  motives  recipro- 
cally introduce  each  other  in   progreflive  trains  or    tribes,  it  is 
termed  catenation  of  animal  motions.     All  thefe  connexions  arc 
faid  to  be  produced  by  habit  ;  that  is  by  frequent  repetition. 

12.  It  may  be  proper  to  obferve,  that  by  the  unavoidable  idi- 
om of  our  language  the  ideas  of  perception,  of  recollection,  or  of 
imagination,  in  the  plural  number  fignify  the  ideas  belonging  to 
perception,  to  recollection,  or  to  imagination  ;  whilft  the  idea 
of  perception,  of  recollection,  or  of  imagination,  in  the  fingular 
number  is  ufed  for  what  is  termed  "  a  reflex  idea  of  any  of  thofe 
operations  of  the  fenforium." 

13.  By  the  wordyfrVw//////  is  not  only  meant  the  application  of 
external  Bodies  to  our  organs  of  fenfe  and  mufcular  fibres,  which 
excites  into  action  the  fenforial  power  termed  irritation  ;  but  al- 
fo  pleafure  or  pain,  when  they  excite  into  action    the  fenforial 
power  termed  fenfation  •,  and  defire  or  averfion,  when  they  ex- 
cite into  action  the  power  of  volition  ;    and   laftly,  the  fibrous 
contractions  which  precede  aflbciation  ;  as  is  further  explained 
in  Seft.  XII.  2.   i. 

SECT. 


MOTIONS  OF  SECT.  III.  i.  i. 


SECT.      HI. 

.THE    MOTIONS    OF    THE    RETINA     DEMONSTRATED   BY   EXPERI- 
MENTS. 

I.  Of  animal  motions  and  of  ideas. — II.  The  fibrous  Jlruflure  of  the 
retina. — III.  The  activity  of  the  retina  in  vifan.  i .  Rays  of 
light  have  no  momentum  2.  Objecls  long  viewed  become  fainter. 

3.  SpecJra  of  black  objects  become  luminous.      4,   Varying  fpeclra 
from  gyration.     5.   From  long  infpeclion  of  various  colours IV. 

Motions  of  the  organs  offenfe  conftitute  ideas.  I.  Light  from 
prejfing  the  eye-ball,  and  found  from  the  pulfation  of  the  carotid  ar- 
tery. 2.  Ideas  in  Jleep  miflaken  for  perceptions.  3.  Ideas  of  im- 
agination produce  pain  andficknefe  like  fen fations.  4.  When  the 
organ  offenfe  is  deftroyed>  the  ideas  belonging  to  that  fenfe  perijh. 
V.  Analogy  between  mufcular  motions  and  fenfual  motions,  or 
ideas.  I.  They  are  both  originally  excited  by  irritations.  2.  And 
officiated  together  in  the  fame  manner.  3.  Both  acJ  in  nearly  the 
fame  times.  4.  Are  alike  Jlrengthened  or  fatigued  by  excercife9 
5.  Are  alike  painful  from  inflammation.  6.  Are  alike  benumb- 
ed by  compreffion.  7.  Are  alike  liable  to  paralyfts.  8.  To  con- 
vulfion.  9 .  21?  the  influence  of  old  age  — VI  (ibjeclions  anfwered 
I.  Why  we  cannot  invent  new  ideas.  2.  If  ideas  refemble  exter- 
nal objecls.  3 .  Of  the  imagined fenfation  in  an  amputated  limb. 

4.  Abjlra£l   ideas. — VII.   What  are  ideas  y  if  they  are  not  ani- 
mal motions  ? 

BEFORE  the  great  variety  of  animal  motions  can  be  duly  ar- 
ranged into  natural  claifes  and  orders,  it  is  neceflary  to  fmooth 
the  way  to  this  yet  unconquered  field  of  fcience,  by  removing 
fome  obftacles  which  thwart  our  paflage.  I.  To  demonftrate 
that  the  retina  and  other  immediate  organs  of  fenfe  poflHs  a 
power  of  motion,  and  that  thefe  motions  conftitute  our  ideas, 
according  to  the  fifth  and  feventh  of  the  preceding  aflertions, 
claims  our  firlt  attention. 

Animal  motions  are  diflinguifhed  from  the  communicated 
motions,  mentioned  in  the  firit  feclion,  as  they  have  no  me- 
chanical proportion  to  their  caufe  ;  for  the  goad  of  a  fpur  on  the 
Ikin  of  a  horfe  ihall  induce  him  to  move  a  load  of  hay.  They 
differ  from  the  gravitating  motions  there  mentioned  as  they  are 
exerted  with  equal  facility  in  all  directions,  and  they  differ  from 
the  chemical  clafs  of  motions,  becauie  no  apparent  decompofi- 
tions  or  new  combinations  are  produced  in  the  moving  ma- 
terials. 

Hence, 


SECT.  III.  i.  i.  THE  RETINA.  9 

Hence,  when  we  fay  animal  motion  is  excited  by  irritation,  we 
do  not  mean  that  the  motion  bears  any  proportion  to  the  me- 
chanical impulfe  of  the  ftimulus  ;  nor  that  it  is  affected  by  the 
general  gravitation  of  the  two  bodies  ;  nor  by  their  chemical 
properties  >  but  folely  that  certain  animated  fibres  are  excited  in- 
to action  by  fomething  external  to  the  moving  organ. 

In  this  fenfe  the  ftimulus  of  the  blood  produces  the  contrac- 
tions of  the  heart  ;  and  the  fubftances  we  take  into  our  ftomach 
and  bowels  flimulate  them  to  perform  their  necefTary  functions. 
The  rays  of  light  excite  the  retina  into  animal  motion  by  their 
ftimulus  ;  at  the  fame  time  that  thofe  rays  of  light  themfelves 
are  phyfically  converged  to  a  focus  by  the  inactive  humours  of 
the  eye.  The  vibrations  of  the  air  ftimulate  the  auditory  nerve 
into  animal  adtion ;  while  it  is  probable  that  the  tympanum  of 
the  ear  at  the  fame  time  undergoes  a  mechanical  vibration. 

To  render  this  circumftance  more  eafy  to  be  comprehended, 
motion  may  be  defined  to  be  a  variation  of  figure ;  for  the  whole 
univerfe  may  be  confidered  as  one  thing  poffefllng  a  certain  fig- 
ure 5  the  motions  of  any  of  its  parts  are  a  variation  of  this  fig- 
ure of  the  whole  :  this  definition  of  motion  will  be  further  ex- 
plained in  Section  XIV.  2.  2.  on  the  production  of  ideas. 

Now  the  motions  of  an  organ  of  fenfe  are  a  fucceflion  of  con- 
figurations of  that  organ  ;  thefe  configurations  fucceed  each 
other  quicker  or  flower  -9  and  whatever  configuration  of  this  or- 
gan of  fenfe,  that  is,  wharever  portion  of  the  motion  of  it  is,  or 
has  ufually  been,  attended  to,  conftitutes  an  idea.  Hence  the 
configuration  is  not  to  be  confidered  as  an  effect  of  the  morion 
of  the  organ,  but  rather  as  a  part  or  temporary  termination  of  it ; 
and  that,  whether  a  paufe  fucceeds  it,  or  a  new  configuration 
immediately  takes  place.  Thus  when  a  fucceflion  of  moving 
objects  are  prefented  to  our  view,  the  ideas  of  trumpets,  horns, 
lords  and  ladies,  trains  and  canopies,  are  configurations,  that  is, 
parts  or  links  of  the  fucceflive  motions  of  the  organ  of  vifion. 

Thefe  motions  or  configurations  of  the  organs  of  fenfe  differ 
from  the  fen forial  motions  to  be  defcribed  hereafter,  as  they  ap- 
pear to  be  fimply  contractions  of  the  fibrous  extremities  of  thofe 
organs,  and  in  that  refpect  exactly  refemble  the  motions  or  con- 
traptions of  the  larger  mufcles,  as  appears  from  the  following 
experiment.  Place  a  circular  piece  of  red  filk  about  an  inch  in 
diameter  on  a  meet  of  white  paper  in  a  ftrong  light,  as  in  Plate 
I. — look  for  a  minute  on  this  area,  or  till  the  eye  becomes  ibme- 
what  fatigued,  and  then,  gently  clofing  your  eyes,  and  (hading 
them  with  your  hand,  a  circular  green  area  of  the  fame  appar- 
ent diameter  becomes  vifible  in  the  doled  eye.  This  green 
area  is  the  colour  reverfe  to  the  red  area,  which  hadxbeen  pre« 
VOL.  I.  C  vioufly 


io  MOTIONS  OF  SECT.  III.  2.  r. 

vioufly  infpeeted,  as  explained  in  the  experiments  on  ocular 
fpe&ra  at  the  end  of  the  work,  and  in  Botanical  Garden,  P.  L 
additional  note.  No.  I.  Hence  it  appears,  that  a  part  of  the  ret- 
ina, which  had  been  fatigued  by  contraction  in  one  direction, 
relieves  itfelf  by  exerting  the  antagonift  fibres,  and  producing  a 
contraction  in  an  oppofite  direction,  as  is  common  in  the  exer- 
tions of  our  mufcles.  Thus  when  we  are  tired  with  long  ac- 
tion of  our  arms  in  one  direction,  as  in  holding  a  bridle  on  a 
journey,  we  occafionally  throw  them  into  an  oppofite  pofition 
to  relieve  the  fatigued  mufcles. 

Mr.  Locke  has  defined  an  idea  to  be  "  whatever  is  prefent  to 
the  mind  :"  but  this  would  include  the  exertions  of  volition, 
and  the  fenfations  of  pleafure  and  pain,  as  well  as  thofe  opera- 
tions of  our  fyftem,  which  acquaint  us  with  external  objects  ; 
and  is  therefore  too  unlimited  for  our  purpofe.  Mr.  Locke 
feems  to  have  fallen  into  a  further  error,  by  conceiving, 
that  the  mind  could  form  a  general  or  abftract  idea  by  its  own 
operation,  which  was  the  copy  of  no  particular  perception  ;  as 
of  a  triangle  in  general,  that  was  neither  acute,,  obtufe,  nor 
right  angled.  The  ingenious  Dr.  Berkley  and  Mr.  Hume  have 
demonftrated  that  fuch  general  ideas  have  no  exiftence  in  na- 
ture, not  even  in  the  mind  of  their  celebrated  inventor  We 
fhall  therefore  take  for  granted  at  prefent,  that  our  recollection 
or  imagination  of  external  objects  confifts  of  a  partial  repetition 
of  the  perceptions,  which  were  excited  by  thofe  external  ob- 
jects, at  the  time  we  became  acquainted  with  them  j  and  that 
our  reflex  ideas  of  the  operations  of  our  minds  are  partial  repe- 
titions of  thofe  operations. 

II.  The  following  article  evinces  that  the  organ  of  vifion  con- 
fifts of  a  fibrous  part  as  well  as  of  the  nervous  medulla,  like  oth- 
er white  mufcles  \  and  hence,  as  it  refembles  the  mufcular  parts 
of  the  body  in  its  ftrufture,  we  may  conclude,  that  it  muft  re- 
femble  them  in  pofTefTing  a  power  of  being  excited  into  animal 
motion.  The  fubfequent  experiments  on  the  optic  nerve,  and 
on  the  colours  remaining  in  the  eye,  are  copied  from  a  paper  on 
ocular  fpectra,  publifhed  in  the  feventy-fixth  volume  of  the  Phi- 
lof  Trani".  by  Dr.  R.  Darwin  of  Shrewfbury  ;  which,  as  I  ihall 
have  frequent  occafion  to  refer  to,  is  printed  in  this  work, 
Sect.  XL. — The  retina  of  an- ox's  eye  was  fufpended  in  a  glafs 
of  warm  water,  and  forcibly  torn  in  a  few  places  ;  the  edges  of 
thefe  parts  appeared  jagged  and  hairy,  and  did  not  contract  and 
become  fmooth  like  fimple  mucus,  when  it  is  diilended  till  it 
breaks,  which  evinced  that  it  confided  of  fibres.  This  fibrous  . 
conftruction  became  (till  more  diftinct  to  the  fight  by  adding 
forne  cuuftic  alkali  to  the  water :  as  the  adhering  mucus  was 

firft 


SECT.  III.  3.  i.  THE  RETINA.  ir 

firft  eroded,  and  the  hair  like  fibres  remained  floating  in  the  vef- 
fel.  Nor  does  the  degree  of  tranfparency  of  the  retina  invali- 
date this  evidence  of  its  fibrous  ftru6lure,  fince  Lseuwenhoek 
has  fhewn,  that  the  cryftalline  humour  itielf  confilis  of  fibres. 
Arc.  Nat.  V.  I.  70. 

Hence  it  appears,  that  as  the  mufcles  confill  of  larger  fibres 
intermixed  with  a  fmaller  quantity  of  nervous  medulla,  the  or- 
gan of  vifion  confifts  of  a  greater  quantity  of  nervous  medulla 
intermixed  with  fmaller  fibres.  It  is  probable  that  the  locomo- 
tive mufcles  of  microfcopic  animals  may  have  greater  tenuity 
than  thefe  of  the  retina  •,  and  there  is  reafon  to  conclude  from 
analogy,  that  the  other  immediate  organs  of  fenfe,  as  the  portio 
mollis  of  the  auditory  nerve,  and  the  rete  mucofum  of  the  Ikin, 
poflefles  a  fimilarity  of  flrufture  with  the  retina,  and  a  fimilar 
power  of  being  excited  into  animal  motion. 

III.  The  fubfequent  articles  (hew,  that  neither  mechanical 
impreffions,  nor  chemical  combinations  of  light,  but  that  the 
animal  activity  of  the  retina  conflitutes  vifion. 

1.  Much  has  been  conjectured  by  philofophers  about  the 
momentum  of  the  rays  of  light  ;  to  fubject  this  to  experiment 
a  very  light  horizontal  balance  was  conftructed  by  Mr.  Michel, 
with  about  an  inch  fquare  of  thin  leaf  copper  fufpended  at  each 
end  of  it,  as  defcribed'  in  Dr.  Prieflley's  Hiftory  of  Light  and 
Colours.     The  focus  of  a  very  large  convex  mirror  was  thrown 
by  Dr.  Powel,  in  his  lectures  on  experimental  philofophy,  in 
my  prefence^  on  one  wing  of  this  delicate  balance,  and  it  reced- 
ed from  the  light  :  thrown  on  the   other  wing,  it  approached 
towards  the  light,  and  this  repeatedly  :  fo  that  no  fenfible  im- 
pulfe  could  be  obferved,  but  what  might  be  well  afcribed  to  the. 
afcent  of  heated  air. 

Whence  it  is  reafonable  to  conclude  that  the  light  of  the  day 
muft  be  much  too  weak  in  its  dilute  (late  to  make  any  mechan- 
ical impreflion  on  fo  tenacious  a  fubftance  as  the  retina  of  the 
eye.  Add  to  this,  that  as  the  retina  is  nearly  tranfparent,  it 
could  therefore  make  lefs  refinance  to  the  mechanical  impulfe 
of  light  ;  which,  according  to  the  obfervations  related  by  Mr. 
Melvil,  in  the  Edinburgh  Literary  EiTays,  only  communicates 
heat,  and  mould  therefore  only  communicate  momentum, 
where  it  is  obflructed,  reflected,  or  refracted.  From  whence 
alfo  may  be  collected  the  final  caufe  of  this  degree  of  tranfpar- 
ency of  the  retina,  viz.  left  by  the  focus  of  ftronger  lights,  heat 
and  pain  mould  have  been  produced  in  the  retina,  inftead  of 
that  ftimuius  which  excites  it  into  animal  motion. 

2.  On  looking  long  on  an  area  of  fcarlet  filk  of  about  an  inch 
in  diameter  laid  on  white  paper,  as  in  Plate  I.  the  fcarlet  colour 


12  MOTIONS  OF  SECT.  III.  3.  3. 

becomes  fainter,  till  at  length,  it  entirely  vanifhes,  though  the 
eye  is  kept  uniformly  and  fteadily  upon  it.  Now  if  the  change 
or  motion  of  the  retina  was  a  mechanical  impreflion,  or  a  chem- 
ical tinge  of  coloured  light,  the  perception  would  every  minute 
become  ftronger  and  ftronger ;  whereas  in  this  experiment  it 
becomes  every  inftant  weaker  and  weaker.  The  fame  circum- 
ftance  obtains  in  the'continued  application  of  found,  or  of  fapid 
bodies,  or  of  odorous  ones,  or  of  tangible  ones,  to  their  adapted 
organs  of  fenfe. 

Thus  when  a  circular  coin,  as  a  (hilling,  is  prefled  on  the 
palm  of  the  hand,  the  fenfe  of  touch  is  mechanically  comprefE- 
ed  ;  but  it  is  the  ftimulus  of  this  preflure  that  excites  the  organ 
of  touch  into  animal  a6Hon,  which  conftitutes  the  perception  of 
hardnefs  and  of  figure  :  for  in  fome  minutes  the  perception 
ceafes,  though  the  mechanical  preflure  of  the  object  remains. 

3.  Make  with  ink  on  white  paper  a  very  black  fpot  about  half 
an  inch  in  diameter,  with  a  tail  about  an  inch  in  length  fo  as 
to  refemble  a  tadpole,  as   in  Plate  II.  ;  look  fleadfaftly   for  a 
minute  on  the  centre  of  this  fpot,  and,  on  moving  the  eye  a  lit- 
tle, the  figure  of  the  tadpole  will  be  feen  on  the  white  part  of 
the  paper ;  which  figure  of  the  tadpole  will  appear  more  lumi- 
nous than  the  other  part  of  the  white  paper  ;  which  can  only 
be  explained  by  fuppofing  that  part  of  the  retina,  on  which  the 
tadpole  was  delineated,  to  have  become  more  fenfible  to  light 
than  the  other  parts  of  it,  which  were  expofed  to  the  white 
paper ;  and   not   from  any  idea  of  mechanical  impreflion  or 
chemical  combination  of  light  with  the  retina. 

4.  When  any  one  turns  round  rapidly,  till  he  becomes  dizzy, 
and  falls  upon  the  ground,   the  fpedtra  of  the  ambient  objects 
continue  to  prefent  themfelves  in  rotation,  and  he  feems  to  be- 
hold the  objects  ftill  in  motion.     Now  if  thefe  fpeftra  were  im- 
preflions  on  a  paflive  organ,   they  either  mufl  continue  as  they 
were  received  laft,  or  not  continue  at  all. 

5.  Place  a  piece  of  red  filk  about  an  inch  in  diameter  on  a 
fheet  of  white  paper  in  a  ftrong  light,  as  in  Plate  I.  ;  look  ftead- 
ily upon  it  from  the  diftance  of  about  half  a  yard  for  a  minute ; 
then  clofmg  your  eye-lids,  cover  them  with  your  hands   and 
handkerchiei,  and  a  green  fpe&rum  will  be  feen  in  your  eyes 
refembling  in  form  the  piece  of  red  filk.     After  fome  feconds 
of  time  the  fpeftrum  will  difappear,  and  in  a  few  more  feconds 
will  reappear  ;  and  thus  alternately  three  or  four  times,  if  the 
experiment  be  well  made,  till  at  length  it  vanifhes  entirely. 

6.  Place  on  a  fheet  of  white  paper  a  circular  piece  of  blue 
{ilk,  about  four  inches  in  diameter,  in  the  funfhine  ;  cover  the 
centre  of  this  with  z  circular  piece  of  yellow  filk,  about  three 

inches 


SECT.  III.  4.  i.  THE  RETINA.  13 

inches  in  diameter ;  and  the  centre  of  the  yellow  filk  with  a 
circle  of  pink  (ilk,  about  two  inches  in  diameter  ;  and  the  cen- 
tre of  the  pink  (ilk  with  a  circle  of  green  (ilk,  about  one  inch  in 
diameter  ;  and  the  centre  of  this  with  a  circle  of  indigo,  about 
half  an  inch  in  diameter  ;  make  a  fmall  fpeck  with  ink  in  the 
very  centre  of  the  whole,  as  in  Plate  III.  look  fteadily  for  a  min- 
ute on  this  central  fpot,  and  then  clofing  your  eyes,  and  applying 
your  hand  at  about  an  inch  diftance  before  them,  fo  as  to  pre- 
vent too  much  or  too  little  light  from  palling  through  the  eye- 
lids, and  you  will  fee  the  moft  beautiful  circles  of  colours  that 
imagination  can  conceive;  which  are  moft  refembled  by  the 
colours  occafioned  by  pouring  a  drop  or  two  of  oil  on  a  ftill 
hke  in  a  bright  day.  But  thefe  circular  irifes  of  colours  are 
not  only  different  from  the  colours  of  the  filks  above  mention- 
ed, but  are  at  the  fame  time  perpetually  changing  as  long  as 
they  exift. 

From  all  thefe  experiments  it  appears,  that  thefe  fpeftra  in 
the  eye  are  not  owing  to  the  mechanical  impulfe  of  light  im- 
prefled  on  the  retina  ;  nor  to  its  chemical  combination  with 
that  organ  ;  nor  to  the  abforption  and  emiflion  of  light,  as  is 
fu;,pofed,  perhaps  erroneoufly,  to  take  place  in  calcined  (hells 
and  other  phofphorefcent  bodies,  after  having  been  expofed  to 
the  light  :  for  in  all  thefe  cafes  the  fpeclra  in  the  eye  (hould  ei- 
ther remain  of  the  fame  colour,  or  gradually  decay,  when  the 
object:  is  withdrawn  ;  and  neither  their  evanefcence  during  the 
pretence  of  the  object,  as  in  the  fecond  experiment,  nor  their 
change  from  dark  to  luminous,  as  in  the  third  experiment,  nor 
their  rotation,  as  in  the  fourth  experiment,  nor  the  alternate 
prefence  and  evanefcence  of  them,  as  in  the  fifth  experiment, 
nor  the  perpetual  change  of  colours  of  them,  as  in  the  laft  ex- 
periment, could  exift. 

IV.  The  fubfequent  articles  (hew,  that  thefe  animal  motions 
or  configurations  of  our  organs  of  fenfe  conltitute  our  ideas. 

1.  If  any  one  in  the  dark  prefTes  the  ball  of  his  eye,  by  ap- 
plying his  finger  to  the  external  corner  of  it,  a  luminous  appear- 
ance is  obferved  ;  and  by  a  fmart  ftroke  on  the  eye  great  flaflies 
of  fire  are  perceived.   (Newton's  Optics.)  So  when  the  arteries, 
that  are  near  the  auditory  nerve,  make  ftronger  pulfations  than 
ufual,  as  in  fome  fevers,  an  undulating  found  is  excited  in  the 
ears.     Hence  it  is  not  the  prefence  of  the  light  and  found,  but 
the  motions  of  the  organ,  that  are  immediately  necefTary  to  con- 
ftitute  the  perception  or  idea  of  light  and  found. 

2.  During  the  time  of  fleep,  or  in  delirium,  the  ideas  of  im- 
agination are  miftaken  for  the  perceptions  of  external  objects  ; 
whence  it  appears,  that  thefe  ideas  of  imagination  are  no  other 

than 


i4  MOTIONS  OF  SECT.  III.  4.  3. 

than  a  reiteration  of  thofe  motions  of  the  organs  of  fenfe,  which 
were  originally  excited  by  the  ftimulus  of  external  obje£ls :  and 
in  our  waking  hours  the  fimple  ideas  that  we  call  up  by  recol- 
lection or  by  imagination,  as  the  colour  of  red,  or  the  fmell  of 
a  rofe,  are  exact  refemblances  of  the  fame  fimple  ideas  from 
perception  ;  and  in  confequence  muft  be  a  repetition  of  thofe 
very  motions. 

3.  The  difagreeable  fenfation  called  the  tooth-edge  is  origin- 
ally excited  by  the  painful  jarring  of  the  teeth  in  biting  the  edge 
of  the  glafs,  or  porcelain  cup,  in  which  our  food  was  given  us 
in  our  infancy,  as  is  further  explained  in  the  Sedlion  XVI.  10, 
on  Inftinct.  This  difagreeable  fenfation  is  afterwards  excited 
not  only  by  a  repetition  of  the  found,  that  was  then  produced, 
but  by  imagination  alone,  as  I  have  myfelf  frequently  experien- 
ced ;  in  this  cafe  the  idea  of  biting  a  china  cup,  when  I  imagine 
it  very  diftinftly,  or  when  I  fee  another  perfon  bite  a  cup  or  * 
glafs,  excites  an  actual  pain  in  the  nerves  of  my  teeth.  So  that 
this  idea  and  pain  feems  to  be  nothing  more  than  the  reiterated 
motions  of  thofe  nerves,  that  were  formerly  fo  difagreeabJy  af- 
fected. 

Other  ideas  that  are  excited  by  imagination  or  recollection 
in  many  inftances  produce  fimilar  effects  on  the  conftitiition,  as 
our  perceptions  had  formerly  produced,  and  are  therefore  un- 
doubtedly a  repetition  of  the  fame  motions.  A  flory  which  the 
celebrated  Baron  Van  Swieten  relates  of  himfelf  is  to  this  pur- 
pofe.  He  was  prefent  when  the  putrid  carcafs  of  a  dead  dog 
exploded  with  prodigious  flench ;  and  fome  years  afterwards, 
accidentally  riding  along  the  fame  road,  he  was  thrown  into  the 
fame  ficknefs  and  vomiting  by  the  idea  of  the  flench,  as  he  had 
before  experienced  from  the  perception  of  it. 

4.  When  the  organ  of  fenfe  is  totally  deftroyed,  the  ideas 
which  were  received  by  that  organ  feem  to  perifh  along  with  it, 
as  well  as  the  power  of  perception.  Of  this  a  fatisfadtory  in- 
fiance  has  fallen  under  my  obfervation.  A  gentleman  about 
fixty  years  of  age  had  been  totally  deaf  for  near  thirty  years  : 
he  appeared  to  be  a  man  of  good  underftanding,  and  amufed 
himfelf  with  reading,  and  by  converfing  either  by  the  ufe  of  the 
pen,  or  by  figns  made  with  his  fingers,  to  reprefent  letters.  I 
obferved  that  he  had  fo  far  forgot  the  pronunciation  of  the  lan- 
guage, that  when  he  attempted  to  fpeak,  none  of  his  words  had 
diftinct  articulation,  though  his  relations  could  fometimes  un- 
deriland  his  meaning.  But,  which  is  much  to  the  point,  he  af- 
fured  me,  that  in  his  dreams  he  always  imagined  that  people 
converfed  with  him  by  figns  or  writing,  and  never  that  he 
heard  any  one  fpeak  to  him.  From  hence  it  appears,  that  with 

the 


§ECT.  III.  5-  I-  THE  RETINA.  15 

the  perceptions  of  founds  he  has  alfo  loft  the  ideas  of  them ; 
though  the  organs  of  fpeech  (till  retain  fomewhat  of  their  ufual 
habits  of  articulation. 

'This  obfervation  may  throw  fome  light  on  the  medical  treat- 
ment of  deaf  people  ;  as  it  may  be  learnt  from  their  dreams 
whether  the  auditory  nerve  be  paralytic,  or  their  deafnefs  be 
owing  to  fome  defect  of  the  external  organ. 

It  rarely  happens  that  the  immediate  organ  of  vifion  is  per- 
fectly deftroyed.  The  mod  frequent  caufes  of  blindnefs  are 
occasioned  by  defects  of  the  external  organ,  as  in  cataracts  and 
obfufcations  of  the  cornea.  But  I  have  had  the  opportunity  of 
converting  with  two  men,  who  had  been  fome  years  blind  ;  one 
of  them  had  a  complete  gutta  ferena,  and  the  other  had  loft  the 
whole  fubftance  of  his  eyes.  They  both  told  me  that  they  did 
not  remember  to  have  ever  dreamt  of  vifible  objects  fince  the 
total  lofs  of  their  fight. 

V.  Another  method  of  difcovering  that  our  ideas  are  animal 
motions  of  the  organs  of  fenfe,  is  from  confidering  the  great 
analogy  they  bear  to  the  motions  of  the  larger  mufcles  of  the 
body.  In  the  following  articles  it  will  appear  that  they  are  orig- 
inally excited  into  action  by  the  irritation  of  external  objects 
like  our  mufcles  ;  are  aflbciated  together  like  our  mufcular  mo- 
tions ;  act  in  fimilar  time  with  them  ;  are  fatigued  by  continu- 
ed exertion  like  them  ;  and  that  the  organs  of  fenfe  are  fubject 
to  inflammation,  numbnefs,  palfy,  convulfion,  and  the  defects 
of  old  age  in  the  fame  manner  as  the  mufcular  fibres. 

1.  All  our  perceptions  or  ideas  of  external  objefts  are  uni- 
verfally  allowed  to  have  been  originally  excited  by  the  ftimulus 
of  thofe  external  objects  ;  and  it  will  be  (hewn  in  a  fucceeding 
fedtion,  that  it  is  probable  that  all  our  mufcular  motions,  as  well 
thofe  that  are  become  voluntary  as  thofe  of  the  heart  and  glan- 
dular fyftem,  were  originally  in  like  manner  excited  by  the  ftim- 
ulus of  fomething  external  to  the  organ  of  motion. 

2.  Our  ideas  are  alfo  aflbciated   together  after  their  produc- 
tion precifely  in  the  fame  manner  as  our  mufcular  motions  ; 
which  will  likewife  be  fully  explained  in  the  fucceeding  fection. 

3.  The  time  taken  up  in  performing  an  idea  is  likewife  much 
the  fame  as  that  taken  up  in  performing  a  mufcular  motion.     A 
mufician  can   prefs  the  keys  of  an  harpfichord  with  his  fingers 
in  the  order  of  a  tune  he  has  been  accuftomed  to  play,  in  as 
little  time  as  he  can  run  over  thofe  notes  in  his  mind.     So  we 
many  times  in  an  hour  cover  our  eye-balls   with  our  eye- lids 
without  perceiving  that  we  are  in  the  dark ;  hence  the  percep- 
tion or  idea  of  light  is  not  changed  for  that  of  darknefs  in  ib 
fmall  a  time  as  the  twinkling  of  an  eye ;  fo  that  in  this  cafe  the 

mufcular 


1 6  MOTIONS  OF  SECT.  III.  5. 4, 

mufcular  motion  of  the  eye-lid  is  performed  quicker  than  the 
perception  of  light  can  be  changed  for  that  of  darknefs.  So  if 
a  fire-flick  be  whirled  round  in  the  dark,  a  luminous  circle  ap- 
pears to  the  obferver ;  if  it  be  whirled  fomewhat  flower,  this 
circle  becomes  interrupted  in  one  part ,  and  then  the  time  taken 
up  in  fuch  a  revolution  of  the  Hick  is  the  fame  that  the  obferver 
ufes  in  changing  his  ideas :  thus  the  ^oXt^o^iov  gy^  of  Homer, 
the  long  fhadow  of  the  flying  javelin,  is  elegantly  defigned  to 
give  us  an  idea  of  its  velocity,  and  not  of  its  length 

4.  The  fatigue  that  follows  a  continued  attention  of  the  mind 
to  one  obje6t  is  relieved  by  changing  the  fubjeft  of  our  thoughts  ; 
as  the  continued  movement  of  one  limb  is  relieved  by  moving 
another  in  its  (lead.      Whereas  a  due  exercife  of  the  faculties  of 
the  mind  ftrengthens  and   improves  thofe  faculties,  whether  of 
imagination  or  recollection ;  as  the  exercife  of  our  limbs  in 
dancing  or  fencing  increafes  the  flrength  and  agility  of  the  muf- 
cles  thus  employed. 

5.  If  the  mufcles  of  any  limb  are  inflamed,  they  do  not  move 
without  pain  ;  fo  when  the  retina  is  inflamed,   its  motions  alfo 
are  painful.     Hence  light  is  as  intolerable  in  this  kind  of  oph- 
thalmia, as  preflure  is  to  the  finger  in  the  paronychia.     In  this 
difeafe  the  patients  frequently  dream  of  having  their  eyes  pain- 
fully dazzled  ;  hence  the  idea  of  ftrong  light  is  painful  as  well 
as  the  reality.     The  firft  of  thefe  fa£ls  evinces  that  our  percep- 
tions are  motions  of  the  organs  of  fenfe  ;  and  the  latter,  that  our 
imaginations  are  alfo  motions  of  the  fame  organs. 

6.  The  organs  of  fenfe,  like  the  moving  mufcles,  are  liable  to 
become  benumbed,  or   lefs  fenfible  from  comprellion.     Thus, 
if  any  perfon  on  a  light  day  looks  on  a  white  wall,  he  may  per- 
ceive the  ramifications  of  the  optic  artery,  at  every  pulfation  of 
it,  reprefented  by  darker  branches  on  the  white  wall ;   which  is 
evidently  owing  to  its  comprefling  the  retina  during  the  diaftole 
of  the  artery.     Sauvages  Nofoiog. 

7.  The  organs  of  fenfe  and  the  moving  mufcles  are  alike  lia- 
ble to  be  affected  with  palfy,  as  in  the  gutta  ferena,  and  in  fome 
cafes  of  deafnefs  ;  and  one  fide  of  the  face  has  fometimes  loft 
its  power  of  fenfation,  but  retained  its  power  of  motion ;  other 
parts  of  the  body  have  loft  their  motions,  but  retained  their  fen- 
fation, as  in   the  common  hemiplegia  •,  and   in  other  inftances 
both  thefe  powers  have  perifhed  together. 

8.  In  fome  convulfive  difeafes  a  delirium  or  infanity  fuper- 
venes,  and  the  convulfions   ceafe ;  and   converfely   the   convul- 
fipns  mall  fupervene,   and  the  delirium  ceafe.     Of  this  I  have 
been  a  witnefs  many  times  in  a  day  in  the  paroxyfms  of  violent 
epilepfies  ;  which  evinces  that  one  kind  of  delirium  is  a  convul- 

fion 


SECT.  HI.  5.  9.  THE  RETINA.  17 

fion  of  the  organs  of  fenfe,  and  that  our  ideas  are  the  motions 
of  thefe  organs  :  the  fubfequent  cafes  will  illuflrate  this  obfer- 
vation. 

Mifs  G ,  a  fair  young  lady,  with  light  eyes  and  hair,  was 

feized  with  moft  violent  convulfions  of  her  limbs,  with  outra- 
geous hiccough,  and  mod  vehement  efforts  to  vomit :  after  near 
an  hour  was  elapfed  this  tragedy  ceafed,  and  a  calm  talkative 
delirium  fupervened  for  about  another  hour ;  and  thefe  relieved 
each  other  at  intervals  during  the  greatefl  part  of  three  or  four 
days.  After  having  carefully  conlidered  this  difeafe,  I  thought 
the  convulfions  of  her  ideas  lefs  dangerous  than  thofe  of  her 
mufcles  ;  and  having  in  vain  attempted  to  make  any  opiate 
continue  in  her  ftomach,  an  ounce  of  laudanum  was  rubbed  along 
the  fpine  of  her  back,  and  a  dram  of  it  was  ufed  as  an  enema  ; 
by  this  medicine  a  kind  of  drunken  delirium  was  continued  ma- 
ny hours  ;  and  when  it  ceaied  the  convulfions  did  not  return  ; 
and  the  lady  continued  well  many  years,  except  fome  (lighter  re- 
lapfes,  which  were  relieved  in  the  lame  manner. 

Mifs  H ,  an  accomplifhed  young  lady,  with  light  eyes  and 

hair,  was  feized  with  convulfions  of  her  limbs,  with  hiccough, 
and  efforts  to  vomit  more  violent  than  words  can  exprefs  ;  thefe 
continued  near  an  hour,  and  were  fucceeded  with  a  cataleptic 
fpafm  of  one  arm,  with  the  hand  applied  to  her  head  ;  and  af- 
ter about  twenty  minutes  theie  fpaims  ceafed,  and  a  talkative 
reverie  fupervened  for  near  an  hour,  from  which  no  violence, 
which  it  was  proper  to  ufe,  could  awaken  her.  Thefe  periods 
of  convulfions,  firft  of  the  mufcles,  and  then  of  the  ideas,  re- 
turned twice  a  day  for  feveral  weeks  ;  and  were  at  length  re- 
moved by  great  dofes  of  opium,  after  a  great  variety  of  other 
medicines  and  applications  had  been  in  vain  experienced  This 
lady  was  fubjeft  to  frequent  relapfes,  once  or  twice  a  year  for 
many  years,  and  was  as  frequently  relieved  by  the  fame  method. 

Mifs  W ,  an  elegant   young  lady,   with  black  eyes  and 

hair,  had  fometimes  a  violent  pain  of  her  fide,  at  other  times  a 
mod  painful  ftrangury,  which  were  every  day  fucceeded  by  de- 
lirium ;  which  gave  a  temporary  relief  to  the  painful  fpaims. 
After  the  vain  exhibition  of  variety  of  medicines  and  applica- 
tions by  different  phyficians,  for  more  than  a  twelvemonth,  (he, 
was  direded  to  take  fome  dofes  of  opium,  which  were  gradually 
increafed,  by  which  a  drunken  delirium  was  kept  up  for  a  day 
or  two  and  the  pains  prevented  from  returning.  A  flefh  diet, 
with  a  little  wine  or  beer,  inftead  of  the  low  regimen  (he  tad 
preyioufly  ufed,  in  a  few  weeks  completely  eftablifhed  her  health  ; 
which,  except  a  few  relapfes,  has  continued  for  many  years. 

9.  Laftly  as  we  advance  in  life  all  the  parts  of  the  body  be- 

Vol.  I.  P  comQ 


1 8  MOTIONS  OF  SECT.  III.  6.  i . 

come  more  rigid,  are  rendered  lefs  fufceptible  of  new  habits  of 
motion,  though  they  retain  thofe  that  were  before  eftablifhed. 
This  is  fenfibly  obferved  by  thofe  who  apply  themfelves  late  in 
life  to  mufic,  fencing,  or  any  of  the  mechanic  arts.  In  the  fame 
manner  many  elderly  people  retain  the  ideas  they  had  learned 
early  in  life,  but  find  great  difficulty  in  acquiring  new  trains  of 
memory  ;  infornuch  that  in  extreme  old  age  we  frequently  fee 
a  forgerfulnefs  of  the  bufinefs  of  yefterday,  and  at  the  fame  time 
a  circumftantial  remembrance  of  the  amufements  of  their  youth  ; 
till  at  length  the  ideas  of  recollection  and  activity  of  the  body 
gradually  ceafe  together, — fuch  is  the  condition  of  humanity  ! 
— and  nothing  remains  but  the  vital  motions  and  fenfations. 

VI.  i.  In  oppofition  to  this  doctrine  of  the  production  of 
our  ideas,  it  may  be  afked,  if  fome  of  our  ideas,  like  other  ani- 
mal motions,  are  voluntary,  why  can  we  not  invent  new  ones, 
that  have  not  been  received  by  perception  ?  The  anfwer  will  be 
better  underftood  after  having  perufed  the  fucceeding  fection, 
where  it  will  be  explained,  that  the  mufcular  motions  like  wife 
ar.e  originally  excited  by  the  ftimulus  of  bodies  external  to  the 
moving  organ  ;  and  that  the  will  has  only  the  power  of  repeat- 
ing the  motions  thus  excited. 

2  Another  objector  may  afk,  Can  the  motion  of  an  organ  of 
fenfe  refemble  an  odour  or  a  colour  ?  To  which  I  can  only  an- 
fwer, that  it  has  not  been  demonftrated  that  any  of  our  ideas  re- 
femble  the  objects  that  excite  them  ;  it  has  generally  been  be- 
lieved that  they  do  not  ;  but  this  (hall  be  difcufled  at  large  in 
Sea.  XIV. 

3.  There  is  another  objection  that  at  fir  ft  view  would  feem 
lefs  eafy  to  furmount.  After  the  amputation  of  a  foot  or  a  finger, 
it  has  frequently  happened,  that  an  injury  being  offered  to 
the  (lump  of  the  amputated  limb,  whether  from  cold  air, 
too  great  preffure,  or  other  accidents,  the  patient  has  com- 
plained of  a  fenfation  of  pain  in  the  foot  or  finger,  that  was 
cut  off.  Does  not  this  evince  that  all  our  ideas  are  excited  in 
the  brain,  and  not  in  the  organs  of  fenfe  ?  This  objection  is 
anfwered,  by  obferving  that  our  ideas  of  the  (hape,  place,  and 
folidity  of  our  limbs,  are  acquired  by  our  organs  of  touch  and 
of  fight,  which  are  fituated  in  our  fingers  and  eyes,  and  not  by 
any  fenfations  in  the  limb  itfelf. 

In  this  cafe  the  pain  or  fenfation,  which  formerly  has  arifen 
in  the  foot  or  toes,  and  been  propagated  along  the  nerves  to  the 
central  part  of  the  fenforium,  was  at  the  fame  time  accompanied 
with  a  vifible  idea  of  the  fhape  and  place,  and  with  a  tangible 
idea  of  the  folidity  of  the  affefted  limb  :  now  when  thefe  nerves 
are  afterwards  affected  by  any  injury  done  to  the  remaining 

ft  iimp 


SECT.  III.  6. 4-  THE  RETINA.  i9 

flump  with  a  fimilar  degree  or  kind  of  pain,  the  ideas  of  the 
fhape,  place,  or  folidity  of  the  loft  limb,  return  by  aiTociation  ; 
as  thefe  ideas  beWhg  to  the  organs  of  fight  and  touch,  on 
which  they  were  fir  ft  excited. 

4.  If  you  wonder  what  organs  of  fenfe  can  be  excited  into 
motion,  when  you  call  up  the  ideas  of  wifdom  or  benevolence, 
which  Mr.  Locke  has  termed  abftracled  ideas  ;  I  afk  you,  by 
what  organs  of  fenfe  you  fir  ft  became  acquainted  with  thefe 
ideas  ?  And  the  anfwer  will  be  reciprocal  ;  for  it  is  certain  that 
all  our  ideas  were  originally  acquired  by  our  organs  of  fenfe  ; 
for  whatever  excites  our  perception  muft  be  external  to  the  or- 
gan that  perceives  it,  and  we  have  no  other  inlets  to  knowledge 
but  by  our  perceptions  :  as  will  be  further  explained  in  Sedlion 
XIV.  and  XV.  on  the  Productions  and  ClafTes  of  ideas. 

VII.  If  our  recollection  or  imagination  be  not  a  repetition  of 
animal  movements,  I  afk,  in  my  turn,  What  is  it  ?  You  tell  me 
it  confifts  of  images  or  pictures  of  things.  Where  is  this  ex- 
tenfive  canvas  hung  up  ?  or  where  are  the  numerous  receptacles 
in  which  thole  are  depofited  ?  or  to  what  elfe  in  the  animal 
iyftem  have  they  any  iimilitude  ? 

That  pleafing  picture  of  objects,  reprefented  in  miniature  on 
the  retina  of  the  eye,  feems  to  have  given  rife  to  this  illufive  or- 
atory !  It  was  forgot  that  this  reprefentation  belongs  rather  to 
the  laws  of  light,  then  to  thofe  of  life  ;  and  may  with  equal  ele- 
gance be  feen  in  the  camera  obfcura  as  in  the  eye ;  and  that  the 
pifture  vanidies  for  ever,  when  the  object  is  with  drawn. 


SECT. 


-o  ANIMAL  CAUSATION-  SECT.  IV. 

SECT.      IV. 

LAWS  OF  ANIMAL  CAUSATION. 

I.  THE  fibres,  which  conftitute  the   mufcles   and  organs  o£ 
fenfe,  poflefs  a  power  of  contraction.     The   circumftances  at- 
tending the  exertion  of  this  power  of  CONTRACTION  conftitute 
the  laws  of  animal  motion,  as  the    circumftances  attending  the 
exertion   of  the   power  of  ATTRACTION  conftitute  the  laws  of 
motion  of  inanimate  matter. 

II.  The  fpirit  of  animation  is  the  immediate  caufe  of  the 
contraction  of  animal  fibres,  it  refides  in  the  brain  and   nerves, 
and  is  liable  to  general  or  partial  diminution  or  accumulation. 

III.  The  ftimulus  of  bodies  external  to  the  moving  organ  is 
'the  remote  caufe  of  the  original  contractions  of  animal  fibres. 

IV.  A  certain  quantity  of  ftimulus  produces  irritation,  which 
is  an  exertion  of  the  fpirit  of  animation  exciting  the  fibres  into 
contraction. 

V  A  certain  quantity  of  contraction  of  animal  fibres,  if  it  be 
perceived  at  all,  produces  pleafure  ;  a  greater  or  lefs  quantity  of 
contraction,  if  it  be  perceived  at  all,  produces  pain  ;  thefe  con- 
ftitute fenfation. 

VI.  A  certain  quantity  of  fenfation  produces  defire  or  aver- 
fion  ;  thefe  conftitute  volition. 

VII.  All  animal  motions  which  have  occurred  at  the  fame 
time,  or  in  immediate  fucceflion,   become   fo   connected,  that 
when  one  of  them  is  reproduced,  the  other  has  a  tendency  to 
accompany  or  fucceed  it.     When  fibrous  contractions  fucceed 
or  accompany  other  fibrous  contractions,  the  connection  is  term- 
ed aflbciation ;  when  fibrous  contractions  fucceed  fenforial  mo- 
tions, the  connection  is  termed  cauiation  ;  when  fibrous  and  fen- 
forial motions  reciprocally   introduce   each  other,   it  is  termed 
catenation  of  animal  motions.     All  thefe  connections  are  faid  to 
be  produced  by  habit,  that  is,  by  frequent  repetition.     Thefe 
laws  of  animal  caufation  will  be  evinced  by  numerous  facts, 
which  occur  in  our  daily  exertions  :  and  will  afterwards  be  em- 
ployed to  explain  the  more  recondite  phenomena  of  the  produc- 
tion, growth,  difeafes,  and  decay  of  the  animal  fyftem, 


SECT. 


SECT.  V.  i*        SENSORIAL  FACULTIES.  21 

SECT.      V. 

OF  THE  FOUR  FACULTIES  OR  MOTIONS  OF  THE  SENSORIUM. 

I.  Four  /enforia/  powers.  2.  Irritation,  fenfation,  volition^  affoci- 
ation  defined.  3.  Senforial  motions  diftinguijbed  from  fibrous  mo- 
tions. 

1.  THE  fpirit  of  animation  has  four  different  modes  of  ac- 
tion, or  in  other  words  the  animal  fenforium  poflefles  four  dif- 
ferent faculties,   which  are  occafionally  exerted,  and  caufe  all 
the  contractions  of  the  fibrous  parts  of  the  body.     Thefe  are 
the  faculty  of  caufing  fibrous  contraftions  in  confequence  of 
the  irritations  excited  by  external  bodies,  in  confequence  of  the 
fenfations  of  pleafure  or  pain,  in  confequence  of  volition,  and  in 
confequence  of  the  aflbciations  of  fibrous  contractions  with  oth- 
er fibrous  contractions,  which  precede  or  accompany  them. 

Thefe  four  faculties  of  the  fenforium  during  their  ina&ive  (late 
are  termed  irritability,  fenfibility,  voluntarity,  and  afibciability  ; 
in  their  aftive  ftate  they  are  termed  as  above,  irritation,  fenfa- 
tion,  volition,  aiTociation. 

2.  IRRITATION  is  an  exertion  or  change  of  fome  extreme 
part  of  the  fenforium  refiding  in  the  mufcles  or  organs  of  fenfe, 
in  confequence  of  the  appulfes  of  external  bodies. 

SENSATION  is  an  exertion  or  change  of  the  central  parts  of  the 
fenforium,  or  of  the  whole  of  it,  beginning  at  fome  of  thofe  ex- 
treme parts  of  it,  which  refide  in  the  mufcles  or  organs  of  fenfe. 

VOLITION  is  an  exertion  or  change  of  the  central  parts  of  the 
fenforium,  or  of  the  whole  of  it,  terminating  in  fome  of  thofe  ex- 
treme parts  of  it,  which  refide  in  the  mufcles  or  organs  of  fenfe* 

ASSOCIATION  is  an  exertion  or  change  of  fome  extreme  part 
of  the  fenforium  refiding  in  the  mufcles  or  organs  of  fenfe,  in 
confequence  of  fome  antecedent  or  attendant  fibrous  contrac- 
tions. 

3  Thefe  four  faculties  of  the  animal  fenforium  may  at  the 
time  of  their  exertions  be  termed  motions  without  impropriety 
of  language  •,  for  we  cannot  pafs  from  a  (late  of  infenfibility  or 
inaction  to  a  ftate  of  fenfibility  or  of  exertion  without  fome 
change  of  the  fenforium,  and  every  change  includes  motion. 
We  fhall  therefore  fometimes  term  the  above  described  facul- 
ties jenforlal  motions  to  diftinguifli  them  from  fibrous  motions  ; 
which  latter  expreffion  includes  the  motions  of  the  mufcles  and 
organs  of  fenfe. 

The  acYive  motions  of  the  fibres,  whether  thofe  of  the  mufcles 


22  SENSORIAL  FACULTIES.        SECT.  V.  3. 

or  organs  of  fenfe,  are  probably  fimple  contractions  j  the  fibres 
being  again  elongated  by  antagonift  mufcles,  by  circulating 
fluids,  or  fometimes  by  elaftic  ligaments,  as  in  the  necks  of 
quadrupeds.  The  fenforial  motions,  which  conftitute  the  fen- 
fations  of  pleafure  or  pain,  and  which  conftitute  volition,  and 
•which  caufe  the  fibrous  contractions  in  confequence  of  irritation 
or  of  aflbciation,  are  not  here  fuppofed  to  be  fluctuations  or  re- 
fluctuations  of  the  fpirit  of  animation  ;  nor  are  they  fuppofed 
to  be  vibrations  or  re  vibrations,  nor  condenfations  or  equilibra- 
tions of  it ;  but  to  be  changes  or  motions  of  it  peculiar  to  life. 


SECT. 


SECT.  VI.  1. 1.    FIBROUS  CONTRACTIONS,  23 

SECT.      VI. 

OF    THE    FOUR    CLASSES   OF    FIBROUS    MOTIONS. 

I.  Origin  of  fibrous  contractions.  II.  Diftribution  of  them  into  four 
c/a/es,  irritative  motions  y  fenfttive  motions ,  voluntary  motions  >  and 
officiate  motions^  defined. 

I.  ALL  the  fibrous  contractions  of  animal  bodies  originate 
from  the  fenforium,  and  refolve  themfelves  into  four  clafles,  cor* 
refpondent  with  the  four  powers  or  motions  of  the  fenforium 
above  defcribed,  and  from  which  they  have  their  caufation. 

1 .  Thefe  fibrous  contractions  were  originally  caufed  by  the 
irritations  excited  by  objects,  which  are  external  to  the  moving 
organ.     As  the  pulfations  of  the  heart  are  owing  to  the  irrita- 
tions excited  by  the  ftimulus  of  the  blood  ;  and  the  ideas  of  per- 
ception are  owing  to  the  irritations  excited  by  external  bodies. 

2.  But  as  painful  or  pleafurable  fenfations  frequently  accom- 
panied thofe  irritations,  by  habit  thefe  fibrous  contractions  be- 
came caufable  by  the  lenfations,  and  the  irritations  ceaied  to  be 
neceflary  to  their  production.     As  the  fecretion  of  tears  in  grief 
is  caufed   by  the  tenfation  of  pain ;  and  the  ideas  of  imagina- 
tion, as  in  dreams  or  delirium,  are  excited  by  the  plqafure  or 
pain,  with  which  they  were  formerly  accompanied. 

3.  But  as  the  efforts  of  the  will  frequently   accompanied 
thefe  painful  or  pleafurable  fenfations,  by  habit  the  fibrous  con- 
tractions became  caufable  by  volition  ;  and  both  the  irritations 
and  feniations  ceafed  to  be  neceflary  to  their  production.     As 
the  deliberate  locomotions  of  the  body,  and  the  ideas  of  recol- 
lection, as  when  we  will  to  repeat  the  alphabet  backwards. 

4.  But  as  many  of  thefe  fibrous  contractions  frequently  ac- 
companied other  fibrous  contractions,    by  habit  they   became 
caufable  by  their   aflbciations   with  them ;  and   the   irritations, 
fenfations,  and  volition,  ceafed  to  be  neceflary  to  their  produc- 
tion.    As  the  actions  of  the  mufcles  of  the  lower  limbs  in  fen- 
cing are  aflbciated  with  thofe  of  the  arms  ;  and  the  ideas  of  fug- 
geftion  are  aflbciated  with  other  ideas,  which  precede  or  accom- 
pany them ;  as  in  repeating  carelefsly  the  alphabet  in  its  ufual 
order  after  having  began  it. 

II.  We  fhall  give  the  following  names  to  thefe  four  clafles  of 
fibrous  motions,  and  fubjoin  their  definitions. 

i.  Irritative  motions.  That  exertion  or  change  of  the  fen  fo- 
rium,  which  is  caufed  by  the  appulfes  of  external  bodies,  either 
fimply  fubfides,  or  is  fucceeded  by  fenfation,  or  it  produces 

fibrous 


24  FIBROUS  CONTRACTIONS.    SECT.  VI.  2.2. 

fibrous  motions  ;  it  is  termed  irritation,  and  irritative  motions 
are  thofe  contractions  of  the  mufcular  fibres,  or  of  the  organs 
of  fenfe,  that  are  immediately  confequent  to  this  exertion  or 
change  of  the  fenforium. 

2.  Senfitive  motions.     That  exertion  or  change  of  the  fenfo- 
tium,  which  conftitutes  pleafure  or  pain,  either  fimply  fubfides, 
or  is  fucceeded  by  volition,  or  it  produces  fibrous  motions  ;  it 
is  termed  ienfation,  and  the  fenfitive  motions  are  thofe  contrao 
tions  of  the  mufcular  fibres,  or  of  the  organs  of  fenfe,  that  arc 
immediately  confequent  to  this  exertion  or  change  of  the  fenfo- 
rium. 

3.  Voluntary  motions.     That  exertion  or  change  of  the  fen- 
forium, which  conftitutes  defire  or  averfion,  either  fimply  fub- 
fides, or  is  fucceeded  by  fibrous  motions  ;  it  is  then  termed  vo- 
lition, and  voluntary  motions  are  thofe  contractions  of  the  muf- 
cular fibres,  or  of  the  organs  of  fenfe,  that  are  immediately  con- 
fequent to  this  exertion  or  change  of  the  fenforium. 

4.  Aflbciate  motions.     That  exertion  or  change  of  the  fen- 
forium, which  accompanies  fibrous  motions,  either  fimply  fub- 
fides, or  is  fucceeded  by  fenfation  or  volition,  or  it  produces 
other  fibrous  motions ;   it  is  then  termed  aflbciation,  and  the  af- 
fociate  motions  are  thofe  contra  'ions  of  the  mufcular  fibres,  or 
of  the  organs  of  fenfe,  that  are  immediately  confequent  to  this 
exertion  or  change  of  the  fenforiurq,. 


SECT 


SECT,  VII.  i.  r.    IRRITATIVE  MOTIONS.  25 


SECT.      VII. 

OF   IRRITATIVE    MOTIONS. 

I.  I.  Some  mufcular  motions  are  excited  by  perpetual  irritations*  2. 
Others  more  frequently  by  fenfations.  3.  Others  by  volition. 
Cafe  of  involuntary  Jl  retchings  in  paralytic  limbs.  4.  Some  fen- 
fual  motions  are  excited  by  perpetual  irritations.  5.  Others  more 
frequently  by  fenfation  or  volition. — II.  I.  Mufcular  motions  ex- 
cited by  perpetual  irritations  occajionally  become  obedient  to  fenfation 
and  to  volition.  2.  And  the  fenfual  motions. — III.  I.  Other  muf- 
cular  motions  are  officiated  with  the  irritative  ones. '  2.  And  other 
ideas  •with  irritative  ones.  Of  letter  s>  language ,  hieroglyphics. 
Irritative  ideas  exift  without  our  attention  to  them. 

1.  i.  MANY  of  our  mufcular  motions  are  excited  by  perpet- 
ual irritations,  as  thofe  of  the  heart  and  arterial  fyftem  by  the 
circumfluent  blood.     Many  other  of  them  are  excited  by  inter- 
mitted irritations,  as  thofe  of  the  ftomach  and  bowels  by  the  ali- 
ment we  fwallow  \  of  the  bile-du6ts  by  the  bile  ;  of  the  kid- 
neys, pancreas,  and  many  other  glands,   by  the  peculiar  fluids 
they  feparatc  from  the  blood  ;  and  thofe  of  the  lacteal  and  oth- 
er abforbent  vefTels  by  the  chyle,  lymph,  and  moifture  of  the  at- 
mofphere.     Thefe  motions  are  accelerated  or  retarded,  as  their 
correfpondent  irritations  are  increafed  or  diminifhed,   without 
our  attention  or  confcioufnefs,  in   the  fame  manntr  as  the  vari- 
ous fccretions  of  fruit,  gum,  refin,  wax,  and  honey,  are  produ- 
ced in  the  vegetable  world,  and  as  the  juices  of  the  earth  and 
the  moifture  of  the  atmofphere  are  abforbed  by^  their  roots  and 
foliage. 

2.  Other  mufcular  motions,  that   are  mod  frequently  con- 
nected with  our  fenfations,  as  thofe  of  the  fphindters  of  the 
bladder  and  anus,  and  the  mufculi  ereciores  penis,  were  origin- 
ally excited  into  motion  by  irritation,  for  young  children  make 
water,  and  have  other  evacuations  without  attention  to  thefe  cir- 
cumftances  ,  "  et  primis  etiam  ab  incunabulis  tjenduntur  faepi- 
us  puerorum  penes,  amore  nundum  expergefaclo."     So  the  nip- 
ples of  young  women  are  liable  to  become  turgid  by  irritation, 
long  before  they  are  in  a  fituation  to  be  excited  by  the  pleafure 
of  giving  milk  to  the  lips  of  a  child. 

3.  The  contractions  of  the  larger  mufcles  of  our  bodies,  that 
are  moil  frequently  connected  with  volition,  were  originally  ex- 
cited into  a&ion  by  internal  irritations  :  as  appears  from  the 
ii  retching  or  yawning  of  all  animals  after  long  fleep      In  the 

VOL.  I.  E  beginning 


<*6  IRRITATIVE  SECT.  VII.  i.  4v 

beginning  of  fome  fevers  this  irritation  of  the  mufcles  produces 
perpetual  ftretching  and  yawning  ;  in  other  periods  of  fever  an 
univerfal  reftlefTnefs  arifes  from  the  fame  caufe,  the  patient 
changing  the  attitude  of  his  body  every  minute.  The  repeated 
ftruggles  of  the  foetus  in  the  uterus  mud  be  owing  to  this  inter- 
nal irritation  :  for  the  foetus  can  have  no  other  inducement  to 
move  its  limbs  but  the  tsedium  or  irkfomenefs  of  a  continued 
pofture. 

The  following  cafe  evinces,  that  the  motions  of  ftretching  the 
limbs  after  a  continued  attitude  are  not  always  owing  to 
the  power  of  the  will.  Mr.  Dean,  a  mafon,  of  Auftry,  in 
Leicefterfhire,  had  the  fpine  of  the  third  vertebra  of  the  back 
enlarged  ;  in  fome  weeks  his  lower  extremities  became  feeble, 
and  at  length  quite  paralytic  :  neither  the  pain  of  blifters,  the 
heat  of  fomentations,  nor  the  utmoft  efforts  of  the  will  could 
produce  the  leafl  motion  in  thefe  limbs  ;  yet  twice  or  thrice  a 
day  for  many  months  his  feet,  legs,  and  thighs,  were  affe&ed 
for  many  minutes  with  forcible  ftretchings,  attended  with  the 
fenfation  of  fatigue  •,  and  he  at  length  recovered  the  ufe  of  his 
limbs,  though  the  fpine  continued  protuberant.  The  fame  cir- 
cum Ranee  is  frequently  feen  in  a  lefs  degree  in  the  common 
hemiplegia  ;  and  when  this  happens,  I  have  believed  repeated 
and  ftroflg  (Locks  of  electricity  to  have  been  of  great  advantage. 

4.  In  like  manner  the  various  organs  of  fenfe   are  originally 
excited  into  motion  by  various  external  ftimuli  adapted  to  this 
purpofe,  which  motions  are  termed  perceptions  or  ideas ;  and 
many  of  thefe  motions  during  our  waking  hours  are  excited  by 
perpetual  irritation,  as  thoie  of  the  organs  of  hearing  and  of 
touch.     The   former  by  the  con  Rant  low  indiftincl:  noifes  that 
murmur  around  us,  and  the  latter  by  the  weight  of  our  bodies 
on  the  parts  which  fupport  them  j  and  by  the  unceating  varia- 
tions of  the  heat,   moifture,  and  preflure  of  the  atmofphere  ; 
and  thefe  fenfual  motions,   precifely  as  the  mufcular  one  above 
mentioned,  obey  their  correfpondent  irritations  without  our  at- 
tention or  confcioufnefs. 

5.  Other  claifes  of  our  ideas  are  more  frequently  excited  by 
our  fenfations  of  pleafure  or  pain,  and  others  by  volition  :  but 
that  thefe  have  all  been  originally  excited  by  Rimuli  from  exter- 
nal objects,  and  only  vary  in  their  combinations  or  feparations, 
]>as  been  fully  evinced  by  Mr.  Locke  :  and  are  by  him  termed 
the  ideas  of  perception  in  contradiilinction  to  thofe,  which  he 
calls  the  ideas  of  reflection. 

II.    i.  Thefe  mufcular  motions,  that  are  excited  by  perpetual 
irritation,  are  neverthelefs  occafionally  excitable  by  the  fenfations 
of  pleafure  or  pain,  or  by  volition  ;  as  appears  by  the  palpita- 
tion 


SECT.  VII.  2. 2.  MOTIONS.  27 

tion  of  the  heart  from  fear,  the  increafed  fecretion  of  faiiva  at 
the  fight  of  agreeable  food,  and  the  glow  on  the  (kin  of  thofe 
who  are  afhamed.  There  is  an  inftance  told  in  the  Philofophi- 
cal  TranfatHons  of  a  man,  who  could  for  a  time  flop  the  mo- 
tion of  his  heart  when  he  pleafed  ;  and  Mr.  D.  has  often  told 
me,  he  could  fo  far  increafe  the  periftaltic  motion  of  his  bowels 
by  voluntary  efforts,  as  to  produce  an  evacuation  by  ftool  at  any 
time  in  half  an  hour. 

2.  In  like  manner  the  fenfual  motions,  or  ideas,  that  are  ex- 
cited by  perpetual  irritation,  are  neverthelefs  occafionally  exci- 
ted by  fenfation  or  volition  ;  as  in  the  night  when  we  liiten 
under  the  influence  of  fear,  or  from  voluntary  attention,  the 
motions  excited  in  the  organ  of  hearing  by  the  whifpering  of 
the  air  in  our  room,  the  pulfation  of  our  own  arteries,  or  the 
faint  beating  of  a  diltant  watch,  become  objects  of  perception. 

III.  I.  Innumerable  trains  or  tribes  of  other  motions  are  af- 
fociated  with  thefe  mufcular  motions  which  are  excited  by  irri- 
tation ;  as  by  the  ftimulus  of  the  blood  in  the  right  chamber  of 
the  heart,  the  lungs  are  induced  to  expand  themfelves  j  and  the 
pe&oral,  and  intercoftal  mufcles,  and  the  diaphragm,  net  at  the 
fame  time  by  their  aflbciations  with  them.  And  when  the  pha- 
rinx  is  irritated  by  agreeable  food,  the  mufcles  of  deglutition  are 
brought  into  a&ion  by  aflbciation.  Thus  when  a  greater  light 
falls  on  the  eye,  the  iris  is  brought  into  action  without  our  at- 
tention, and  the  cilinary  procefs,  when  the  focus  is  formed  be- 
fore or  behind  the  retina,  by  their  aflbciations  of  tlie  increaf- 
ed irritative  motions  of  the  organ  of  vifion.  Many  common 
actions  of  life  are  produced  in  a  fimilar  manner.  If  a  fly  fettle 
on  my  forehead,  whild  I  am  intent  on  my  prefent  occupation, 
I  diflodge  it  with  my  finger,  without  exciting  my  attention  or 
breaking  the  train  of  my  ideas. 

2.  In  like  manner  the  irritative  ideas  fuggeft  to  us  many  oth- 
er trains  or  tribes  of  ideas  that  are  aflbciated  with  them.  On 
this  kind  of  connexion,  language,  letters,  hieroglyphics,  and  ev- 
ry  kind  of  iymbol,  depend.  The  fymbnls  themfelves  produce 
irritative  ideas,  or  fenfual  motions,  which  we  do  not  attend  to ; 
and  other  ideas,  that  are  fucceeded  by  fenfation,  are  excited  by 
their  aflbciation  with  them.  And  as  thefe  irritative  ideas  make 
up  a  part  of  the  chain  of  our  waking  thoughts,  introducing  oth- 
er ideas  that  engage  our  attention,  though  themfelves  are  unat- 
tended to,  we  find  it  very  difficult  to  inveftigate  by  what  iteps 
many  of  our  hourly  trains  of  ideas  gain  their  admittance. 

It  may  appear  paradoxical,  that  ideas  can  exift,  rind  not  be  at- 
tended to ;  but  all  our  perceptions  are  ideas  excited  by  irrita- 
tion, and  fucceeded  by  fenfation.  Now  when  thefe  ideas  exci- 
ted 


2S  IRRITATIVE  MOTIONS.      SECT.  VII.  3. 2. 

ted  by  irritation  give  us  neither  pleafure  nor  pain,  we  ceafe  to 
attend  to  them.  Thus  whilft  I  am  walking  through  that  grove 
before  my  window,  I  do  not  run  againft  the  trees  or  the  benches, 
though  my  thoughts  are  ftrenuoufly  exerted  on  fome  other  ob- 
ject. This  leads  us  to  a  diftind  knowledge  of  irritative  ideas, 
for  the  idea  of  the  tree  or  bench  which  I  avoid,  exifts  on  my 
retina,  and  induces  by  aflbciation  the  aftion  of  certain  locomo- 
tive mufcles  ;  though  neither  itfelf  nor  the  adions  of  thofe  muf- 
cles  engage  my  attention. 

Thus  whilft  we  are  converting  on  this  fubjecT;,  the  tone,  note, 
and  articulation  of  every  individual  word  forms  its  correfpondent 
irritative  idea  on  the  organ  of  hearing  ;  but  we  only  attend  to 
the  aflbciated  ideas,  that  are  attached  by  habit  to  thefe  irritative 
ones,  and  are  fucceeded  by  fenfation  ;  thus  when  we  read  the 
words  "  PRINTING-PRESS"  we  do  not  attend  to  the  fhape,  fize, 
or  exiftence  of  the  letters  which  compofe  thefe  words,  though 
each  of  them  excites  a  correfpondent  irritative  motion  of  our 
organ  of  vifion,  but  they  introduce  by  aflbciation  our  idea  of  the 
moft  ufeful  of  modern  inventions ;  the  capacious  refervoir  of 
human  knowledge,  whofe  branching  dreams  diffufe  fcienceSj 
arts,  and  morality,  through  all  nations  and  all  ages. 


SECT. 


SECT.  VIIL  1. x.       SENSITIVE  MOTIONS.  29 


SECT.      VIIL 

OF   SENSITIVE    MOTIONS. 

I.  I .  Senfitive  mufcular  motions  were  originally  excited  into  aflion 
by  irritation.  2  And  Jenfttive  fenfual  motions,  ideas  oj  imagina- 
tion^ dreams.— H  \ .  *Senfitive  mufcular  motions  are  occajionally 
obedient  to  volition.  2.  An d  fenfittve  fenfual  motions. — III.  i. 
Other  mufcular  motions  are  ajfbciated  with  the  fenfitive  ones.  2. 
And  other  fenfual  motions. 

I.  i.  MANY  of  the  motions  of  our  mufcles,  that  are  excited 
into  aftion  by  irritation,  are  at  the  fame  time  accompanied  with 
painful  or  pleafuvable  feniations ;  and  at  length  become  by 
habit  caufable  by  the  fen  Nations.  Thus  the  motions  of  the 
fphmclers  of  the  bladder  and  anus  were  originally  excited  into 
adtion  by  irritation  ;  for  young  children  give  no  attention  to 
thefe  evacuations  ;  but  as  foon  as  they  become  fenfible  of  the 
inconvenience  of  obeying  thefe  irritations,  they  furTer  the  water 
or  excrement  to  accumulate,  till  it  difagreeably  afFe&s  them  j 
and  the  action  of  thole  iphinftures  is  then  in  conlequence  of  this 
difagreeable  fenfation.  So  the  fecretion  of  faliva,  which  in 
young  children  is  copiouflv  produced  by  irritation,  and  drops 
from  'heir  mouths,  is  frequently  attended  with  the  agreeable 
fenfation  produced  by  the  maftication  of  tafteful  food  ;  till  at 
length  the  fight  of  fuch  food  to  a  hungry  perfon  excites  into 
a£lion  thefe  falival  glands  ;  as  is  feen  in  the  Havering  of  hungry 
dogs. 

The  motions  of  thofe  mufcles,  which  are  affec~ted  by  lafcivi- 
ous  ideas,  and  thofe  which  are  exerted  in  fmiling,  weeping, 
Itarting  from  fear,  and  winking  at  the  approach  of  danger  to 
the  eye,  and  at  times  the  aclions  of  every  large  mufcle  of  the 
body  become  caufable  by  our  fenfations.  And  all  thefe  motions 
are  performed  with  ftrength  and  velocity  in  proportion  to  the 
energy  of  the  fenfation  that  excites  them,  and  the  quantity  of 
fenforial  power. 

2.  Many  of  the  motions  of  our  organs  of  fenfe,  or  ideas,  that 
were  originally  excited  into  aclion  by  irritation,  become  in  like 
manner  more  frequently  caufable  by  our  fenfations  of  pleafure 
or  pain.  Thefe  motions  are  then  termed  the  ideas  of  imagina- 
tion, and  make  up  all  the  fcenery  and  tranfa&ions  of  our 
dreams.  Thus  when  any  painful  or  pleafurable  fenfations  pof- 
fefs  us,  as  of  love,  anger,  fear  ;  whether  in  our  ileep  or  waking 
hours,  the  ideas  that  have  been  formerly  excited  by  the  objecls 

of 


3o  SENSITIVE  MOTIONS.      SECT.  VIII.  2.  r. 

of  thefe  fenfations,  now  vividly  recur  before  us  by  their  con- 
nexion with  thefe  fenfations  themfelves.  So  the  fair  fmiling 
virgin,  that  excited  your  love  by  her  prefence,  whenever  that 
fenfation  recurs,  rifes  before  you  in  imagination  ;  and  that  with 
all  the  pleafmg  circumftances  that  had  before  engaged  your  at- 
tention. And  in  fleep,  when  you  dream  under  the  influence  of 
fear,  all  the  robbers,  fires,  and  precipices,  that  you  formerly 
have  feen  or  heard  of,  arife  before  you  with  terrible  vivacity.  All 
thefe  fenfuai  motions,  like  the  mufcular  ones  above  mentioned, 
are  performed  with  flrength  and  velocity  in  proportion  to  the 
energy  of  the  fenfation  of  pleafure  or  pain,  which  excites  them, 
and  the  quantity  of  fenforial  power. 

II.  i    Many  of  thefe  mufcular  motions  above  defcribed,  that 
are  moil  frequently  excited  by  our  fenfations,  are  neverthelefs 
occafionally  cauiable  by  volition ;  for   we   can   fmile  or  frown 
fpontaneoufly,  can  make  water  before  the  quantity  or  acrimony 
of  the  urine  produces  a  difagreeable  fenfation,  and  can  volunta- 
rily mafticate  a   naufeous  drug,    or  fvvallow   a  bitter  draught, 
though  our  fenfation  would  ftrongly  difluade  us. 

2.  In  like  manner  the  fenfuai  motions,  or  ideas,  that  are  mod 
frequently  excited  by  our  fenfations,  are  neverthelefs  occafion- 
ally caufable  by  volition,  as  we  can  fpomaneoufly  call  up  our 
laft  night's  dream  before  us>  tracing  it  indu  trioufly  itep  by  (tep 
through  all  its  variety  of  fcenery  and  tranfa6Hons  ;  or  can  vol- 
untarily examine  or  repeat  the  ideas,  that  have  been  excited  by 
our  difguit  or  admiration. 

III.  i.  Innumerable  trains  or  tribes  of  motions  are  aflbciated 
with  thefe  fenfitive  mufcular  motions  above  mentioned  ;  as  when 
a  drop  of  water  falling  into  the    wind-pipe  difagreeably  affefts 
the  air-veflels  of  the  lungs,  they  are  excised  into  violent  a<ftion  ; 
and  with  thefe  fenfitive  motions  are  aflbciated  the  adions  of  the 
pedoral  and  intercoital   mufcles,   and   the  diaphragm  ;  till  by 
their    united    and    repeated    fucceffions   the   drop   is   returned 
through  the  larinx.      The  fame  occurs  when  any  thing  difagree- 
ably affefts  the  noftrils,  or  the  (lomach,  or  the  uterus  ;  variety 
of  mufcles  are  excited  by  aflbciation  into  forcible  aftion,  not  to 
be  fupprefTed  by  the  utmofl  efforts  of  the  will ;  as  in  fneezing, 
vomiting,  and  parturition. 

2.  In  like  manner  with  thefe  fenfitive  fenfuai  motions,  or  ideas 
of  imagination,  are  aflbciated  many  pther  trains  or  tribes  of 
ideas,  which  by  fome  writers  of  metaphyfics  have  been  clafled 
under  the  terms  of  refemblance,  caufation  and  contiguity  ;  and 
will  be  more  fully  treated  of  hereafter. 

SECT, 


SECT.  IX.  i.  i.       VOLUNTARY  MOTIONS.  31 


SECT.      IX. 

OF   VOLUNTARY    MOTIONS. 

I.  I .  Voluntary  mitfcitlar  motions  are  originally  excited  by  irritations. 
2.  And  voluntary  ideas.  Of  reafon. — II.  I.  Voluntary  mufcular 
motions  are  occasionally  can  fable  by  fenfations.  2.  And  voluntary 
ideas. — III.  I .  Voluntary  mufcular  motions  are  occafionally  obe- 
dient to  irritations.  2.  And  voluntary  ideas. — IV.  I.  Volun- 
tary mufcular  motions  are  ajfociated  with  other  mufcular  motion:. 
2.  And  voluntary  ideas. 

WHEN  pleafure  or  painafFeft  the  animal  fyftem,  many  of  its 
motions  both  mufcular  and  fenfual  are  brought  into  aftion  ;  as 
v/as  (hewn  in  the  preceding  fe£fcion,  and  were  called  fenfitive 
motions.  The  general  tendency  of  thefe  motions  is  to  arreft 
and  to  poffefs  the  pleafure,  or  to  diflodge  or  avoid  the  pain  :  but 
if  this  cannot  immediately  be  accomplished,  defire  or  averfion  is 
produced,  and  the  motions  in  confequence  of  this  new  faculty 
of  the  fenforium  are  called  voluntary. 

1.  i.  Thofe  mufcles  of  the  body  that  are  attached  to  bones, 
have  in  general   their  principal  connexions  with  volition,   as  I 
move  my  pen  or  raife  my  body.     Thefe  motions  were  original- 
ly excited  by  irritation,  as  was  explained  in  the  fe&ion  on  that 
fubjecl,  afterwards  the  fenfations  of  pleafure  or  pain,  that  accom- 
panied the  motions  thus  excited,  induced  a  repetition  of  them  ; 
and  at  length  many  of  them  were   voluntarily  pra&ifed  in  fuc- 
ceflion  or  in  combination  for  the  common  purpofes  of  life,  as 
in  learning  to   walk,  or  to   fpeak  ;  and   are   performed    with 
ftrength  and  velocity  in  proportion  to  the  energy  of  the  volition, 
that  excites  them,  and  the  quantity  of  fenforial  power. 

2.  Another  great   clafs  of  voluntary  motions  confifts  of  the 
ideas  of  recollection.     We  will  to  repeat  a  certain  train  of  ideas, 
as  of  the  alphabet  backwards  ;  and  if  any  ideas  that  do  not  be- 
long to  this  intended  train,  intrude  themfelves  by  other  connex- 
ions, we  will  to  rejecl  them,  and  voluntarily  perlift  in  the  deter- 
mined train.     So  at  my  approach  to  a  houfe  which  I  have  but 
once  vifited,  and  that  at  the  dittance  of  many  months,  I  will  to 
recollect  the  names  of  the  numerous  family  I  expert  to  fee  there,  < 
and  I  do  recollecT:  them. 

On  this  voluntary  recollection  of  ideas  our  faculty  of  reafon 
depends,  as  it  enables  us  to  acquire  an  idea  of  the  diflimilitude 
of  any  two  ideas.  Thus  if  you  voluntarily  produce  the  idea  of 
a  right-angled  triangle,  and  then  of  a  fquare ;  and  after  having 

excited 


32  VOLUNTARY  MOTIONS.       SECT.  IX.  2.  i. 

excited  thefe  ideas  repeatedly,  you  excite  the  idea  of  their  differ- 
ence,  which  is  that  of  another  right  angled  triangle  inverted 
over  the  former ;  you  are  faid  to  reafon  upon  this  fubject,  or 
to  compare  your  ideas. 

Thefe  ideas  of  recolle£iion,  like  the  rnufcular  motions  above 
mentioned,  were  originally  excited  by  the  irritation  of  external 
bodies,  and  were  termed  ideas  of  perception ;  afterwards  the 
pleafure  or  pain,  that-accompanied  thefe  motions,  induced  a  rep- 
etition of  them  in  the  abfence  of  the  external  body,  by  which 
they  were  firil  excited  ;  and  then  they  were  termed  ideas  of 
imagination.  At  length  they  become  voluntarily  pradlifed  in 
fucceffion  or  in  combination  for  the  common  purpofes  of  life  ;  as 
when  we  make  ourfelves  matters  of  the  hiilory  of  mankind,  or  of 
the  fciences  they  have  inveitigated  ;  and  are  then  called  ideas  of 
recollection  ;  and  are  performed  with  ftrcngth  and  velocity  in 
proportion  to  the  energy  of  the  volition  that  excites  them,  and 
the  quantity  of  feriforial  power. 

II.  i.  The  mufcular  motions  above  defcribedj  that  are  mod 
frequently  obedient  to  the   will,  are  neverthelefs  occasionally 
caufable  by  painful  or  pleafurable  fenfation,  as  in  the  ftarting 
from  fear,  and  the  contraction  of  the  calf  of  the  leg  in  the 
cramp. 

2.  In  like  manner  the  fenfual  motions,  or  ideas,  that  are  moil 
frequently  connected  with  volition,  are  neverthelefs  occafionally 
cauiable  by  painful  or  pleafurable  fenfation.  As  the  hiftories  of 
men,  or  the  defcription  of  places,  which  we  have  voluntarily 
taken  pains  to  remember,  fometimes  occur  to  us  in  our 
dreams. 

III.  i.  The  mufcular  motions  that  are  generally  fubfervienl 
to  volition,   are  alfo  occafionally   caufable  by  irritation,  as  in 
ftretching  the  limbs  after  fleep,   and  yawning.     In  this  manner 
a  contraction  of  the  arm  is  produced  by  palling  the  electric  fluid 
from  the  Leyden  phial  along  its  mufcles  ;  and  that  even  though 
the  limb  is  paralytic.     The  fudden  morion  of  the  arm  produces 
a  difagreeabie  fenfation  in  the  joint,  but  the  mufcles  feem  to  be 
brought  into  action  {imply  by  irritation. 

i.  The  ideas,  that  are  generally  fubfervient  to  the  will,  are 
in  like  manner  occafionally  excited  by  irritation  ;  as  when  we 
view  again  an  object,  we  have  before  well  itudied,  and  often 
recollected. 

IV.  i.  Innumerable  trains  or  tribes  of  motions  are  aflbciated 
with  thefe  voluntary  mufcular  motions  above    mentioned  ;    as 
when  I  will  to  extend  my  arm  to  a  diitant  object,   fome  other 
mufcles  are  brought  into  action,  and  preferve  the  balance  of  my 
body.     And  when  I  wifh  to  perform  any  iteady  exertion,  as  ia 

threading 


SECT.  IX.  4. 2.        VOLUNTARY  MOTIONS.  33 

threading  a  needle,  or  chopping  with  an  ax,  the  peftoral  mufcles 
are  at  the  fame  time  brought  into  aftion  to  preferve  the  trunk 
of  the  body  motionlefs,  and  we  ceafe  to  refpire  for  a  time. 

2.  In  like  manner  the  voluntary  fenfual  motions,  or  ideas  of 
recollection,  are  aflbciated  with  many  other  trains  or  tribes  of 
ideas.  As  when  I  voluntarily  recoiled  a  Gothic  window,  that  I 
faw  fome  time  ago,  the  whole  front  of  the  cathedral  occurs 
to  me  at  the  fame  time. 


TOL.  I.  F  SECT. 


3-4  ASSOCIATE  SECT.  X.  i.  i. 

SECT.       X. 

OF    ASSOCIATE    MOTIONS. 

I.  I.  Many  mufcular  motions  excited  by  irritations  in  trains  or 
tribes  become  officiated.  2.  And  many  ideas. — II.  I.  Many 
fenfitive  mufcular  motions  become  ajjociated.  2.  And  many  fen- 
Jitive  ideas. — III.  I.  Many  voluntary  mufcular  motions  become 
officiated.  2.  And  then  become  obedient  to  fenfation  or  irritation^ 
3.  And  many  voluntary  ideas  become  ajjociated. 

ALL  the  fibrous  motions,  whether  mufcular  or  fenfual,  which 
are  frequently  brought  into  adion  together,  either  in  combined 
tribes,  or  in  fucceflive  trains,  become  fo  connedted  by  habit,  that 
when  one  of  them  is  reproduced  the  others  have  a  tendency  to 
fucceed  or  accompany  it. 

1.  i.  Many  of  cur  mufcular  motions  were  originally  excited 
in  fucceflive  trains,  as  the  contra6lions  of  the  auricles  and  of 
the  ventricles  of  the  heart ;  and  others  in  combined  tribes,  as 
the  various  divifions  of  the  mufcles  which  compofe   the  calf  of 
the  leg,  which  were  originally  irritated  into  fynchronous  a&ion 
by  the  txdiurn  or  irkfomenefs  of  a  continued  poflure.     By  fre- 
quent repetitions  thefe  motions  acquire  affociations,  which  con- 
tinue during  our  lives,  and  even  after  the  deflruftion  of   the 
greater!  part  of  the  fenforium  •,  for  the  heart  of  a  viper  or  frog 
will  continue  to  pulfate  long   after  it  is  taken  from  the  body ; 
and  when  it  has  entirely  ceafed  to  move,   if  any  part  of  it   is 
goaded  with  a  pin,  the  whole  heart  will  again  renew  its  pulfa- 
tions.     This  kind  of  connexion  we  (hall  term  irritative  afTocia- 
tlon,  to  diitinguiuh  it  from  fenfitive  and  voluntary  aflbciations. 

2.  In  like  manner,  many  of  our  ideas  are  originally  excited  in 
tribes ;  as  all  the  objefts  of  fight,  after  we  become  fo  well  ac- 
quainted with  the  laws  of  vifion,  as  to  clillinguim  figure  and  dif- 
tance  as  well  as  colour  ;  or  in  trains,  as  while  we  pafs  along  the 
objedls  that  furround  us.     The  tribes  thus  received  by  irritation 
become  aiTociated  by  habit,  and  have  been  termed  complex  ideas 
by  the  writers  of  metaphyfics,  as  this  book,  or  that  orange.    The 
trains  have  received  no  particular  name,  but   thefe  are  alike  af- 
ibciations  of  ideas,   and  frequently   continue  during  our   lives. 
So  the  tafle  of  a  pine-apple,  though  we  eat  it   blindfold,  recals 
the  colour  and  fhape  of  it  j  and  we  can  fcarcHy  think  on  folidity 
without  figure. 

II.  i.  By  the  various  efforts  of  our  fenfations  to  acquire  or 
avoid -their  objects,  many  mufcles  are  daily  brought  into  fuccef- 

five 


SECT.  X.  2. 2.  MOTIONS.  35 

five  or  fynchronous  a&ions  ;  thefe  become  afibciated  by  habit, 
-and  are  then  excited  together  with  great  facility,  and  in  many 
initances  gain  indiffbluble  connexions.  So  the  play  of  puppies 
and  kittens  is  a  reprefentation  of  their  mode  of  fighting  or  of 
taking  their  prey  i  and  the  motions  of  the  mufcles  hecefiary  for 
thofe  purpofes,  become  afibciated  by  habit,  and  gain  a  great 
adroitnefs  of  action  by  thefe  early  repetitions  ;  fo  the  motions 
of  the  abdominal  mufcles,  which  were  originally  brought  into 
concurrent  action  with  the  protufive  motion  of  the  rectum  or 
bladder  by  fenfation,  become  fo  conjoined  with  them  by  habit, 
that  they  not  only  eafily  obey  thefe  fenfations,  occafioned  by  the 
flimulus  of  the  excrement  and  urine,  but  are  brought  into  vio- 
lent and  unreftrainable  adlion  in  the  flrangury  and  tenefmus. 
This  kind  of  connexion  we  fhall  term  fenfitive  aiTociation. 

2.  So  many  of  our  ideas,  that  have  been  excited  together  or 
in  fucceflion  by  our  fenfations,  gain  fynchronous  or  fucceflive 
afTociaticns,  that  are  fometimes  ir.difloluble  but  with  life.  Hence 
the  idea  of  an  inhuman  or  difhonourable  action  perpetually  calls 
up  before  us  the  idea  of  the  wretch  that  was  guilty  of  it.  And 
hence  thofe  unconquerable  antipathies  are  formed,  which  fome 
people  have  to  the  fight  of  peculiar  kinds  of  food,  of  which  in 
their  infancy  they  have  eaten  to  excefs,  or  by  conflraint. 

III.  i.  In  learning  any  mechanic  art,  as  mufic,  dancing,  or 
the  ufe  of  the  fword,  we  teach  many  of  our  mufcles  to  act  to- 
gether or  in  fucceflion  by  repeated  voluntary  efforts ;  which  by 
habit  become  formed  into  tribes  or  trains  of  aflbciation,  and 
ferve  all  our  purpofes  with  great  facility,  and  in  fome  inftances 
acquire  an  indifToluble  union.  Thefe  motions  are  gradually 
formed  into  a  habit  of  acHng  together  by  a  multitude  of  repeti- 
tions, whil ft  they  are  yet  feparately  caufable  by  the  will,  as  is 
evident  from  the  long  time  that  is  taken  up  by  children  in  learn- 
ing to  walk  and  to  fpeak  ;  and  is  experienced  by  every  one, 
when  he  firft  attempts  to  fkate  upon  the  ice  or  to  fwim  :  thefe 
we  fhall  term  voluntary  affociations. 

2.  All  thefe  mufcular  movements,  when  they  are  thus  aflbci- 
ated into  tribes  or  trains,  become  afterwards  not  only  obedient 
to  volition,  but  to  the  fenfations  and  irritations ;  and  the  fame 
movement  compofes  a  part  of  many  different  tribes  or  trains  of 
motion.  Thus  a  (ingle  mufcle,  when  it  acts  in  confort  with  its 
neighbours  on  one  fide,  afiifts  to  move  the  limb  in  one  direction  ; 
and  in  another,  when  it  acts  with  thofe  in  its  neighbourhood  on 
the  other  fide  ;  and  in  other  directions,  when  it  acts  feparately 
or  jointly  with  thofe  that  lie  immediately  under  or  above  it ;  and 
all  thefe  with  equal  facility  after  their  affociations  have  been 
well  eftahlifned. 

The 


36  ASSOCIATE  MOTIONS.          SECT.  X,  3. 3. 

The  facility,  with  which  each  mufcle  changes  from  one  affo- 
ciated  tribe  to  another,  and  that  either  backwards  or  forwards, 
is  well  obfervable  in  the  mufcles  of  the  arm  in  moving  the  wind- 
Jafs  of  an  air-pump  ;  and  the  ilownefs  of  thofe  mufcular  move- 
ments, that  have  not  been  affociated  by  habit,  may  be  experi- 
enced by  any  one  who  (hall  attempt  to  faw  the  air  quick  per- 
pendicularly with  one  hand,  and  horizontally  with  the  other  at 
the  fame  time. 

3.  In  learning  every  kind  of  fcience  we  voluntarily  affociate 
many  tribes  and  trains  of  ideas,  which  afterwards  are  ready  for 
all  the  purpofes  either  of  volition,  fenfation,  or  irritation  ;  and 
in  fome  inftances  acquire  indhToluble  habits  of  afting  together, 
fo  as  to  affect  our  reaioning,  and  influence  our  actions.  Hence 
the  neceffify  of  a  good  education. 

Thefe  affociate  ideas  are  gradually  formed  into  habits  of  a£l- 
ing  together,  by  frequent  repetition,  while  they  are  yet  feparately 
obedient  to  the  will  •,  as  is  evident  from  the  difficulty  we  experi- 
ence in  gaining  fo  exacft  an  idea  of  the  front  of  St.  Paul's  church, 
as  to  be  able  to  delineate  it  with  accuracy,  or  in  recollecting  a 
poem  of  a  few  pages. 

And  thefe  ideas,  thus  affociated  into  tribes,  not  only  make  up 
the  parts  of  the  trains  of  volition,  fenfation,  and  irritation  ;  but 
the  fame  idea  compofes  a  part  of  many  different  tribes  and  trains 
of  ideas.  So  the  fimple  idea  of  whitenefs  compofes  a  part  of  the 
complex  idea  of  fnow,  milk,  ivory  ;  aiid  the  complex  idea  of  the 
letter  A  compofes  a  part  of  the  feveral  affociated  trains  of  ideas 
that  make  up  the  variety  of  words,  into  which  this  letter  enters. 

The  numerous  trains  of  thefe  affociated  ideas  are  divided  by 
Mr.  Hume  into  three  claffes,  which  he  has  termed  contiguity, 
caufation,  and  refemblance.  Nor  fhould  we  wonder  to  find 
them  thus  connected  together,  fince  it  is  the  bufmefs  of  our 
lives  to  difpofe  them  into  thefe  three  claffes  ;  and  we  become 
valuable  to  ourfelves  and  our  friends,  as  we  fucceed  in  it.  Thofe 
\vho  have  combined  an  extenfive  clafs  of  ideas  by  the  contiguity 
of  time  or  place,  are  men  learned  in  the  hiftory  of  mankind,  and 
of  the  fciences  they  have  cultivated.  Thofe  who  have  conneft- 
ed  a  great  clafs  of  ideas  of  refernblances,  poffefs  the  fource  of 
the  ornaments  of  poetry  and  oratory,  and  of  all  rational  analo- 
gy. While  thofe  who  have  conne&cd  great  claffes  of  ideas  of 
caufation,  are  furnifhcd  with  the  powers  of  producing  effects. 
Thefe  are  the  men  of  aftive  wifdom,  who  lead  armies  to  victory, 
and  kingdoms  to  profperity  ;  or  difcover  and  improve  the  fci- 
ences, which  meliorate  and  adorn  the  condition  of  humanity. 


SECT. 


SECT.  XI.  i.          SENSORIAL  ACTIONS.  37 

SECT.      XI. 

ADDITIONAL    OBSERVATIONS    ON    THE    SENSORIAL    POWERS. 

I.  Stimulation  is  of  various  kinds,  adapted  to  the  organs  of  fenfe,  to 
the  mufcles  t  to  hollow  membranes  and  glands.  Some  objecls  irri- 
tate our  fenfes  by  repeated  impulfes  — II.  I.  Sefifation  and  volition 
frequently  (iff eft  the  whole  fenforium.  2.  Emotions ',  pnffions,  ap- 
petites. 3 .  Origin  of  defire  and  averfton.  Criterion  of  volunta- 
ry aftionsy  difference  of  brutes  and  men.  4.  Senftbility  and  vol- 
untarily.— ill.  Affbcidtiom  formed  before  nativity ,  irritative  mo- 
tions mijlaken  for  officiated  ones. 

Irritation. 

I.  THE  various  organs  of  fenfe  require  various  kinds  of  ftim- 
ulation  to  excite  them  into  action ;  the  particles  of  light  pene- 
trare  the  cornea  and  humours  of  the  eye,  and  then  irritate  the 
naked  retina ;  fapid  particles,  diflblved  or  diffufed  in  water  or 
faliva,  and  odorous  ones,  mixed  or  combined  with  the  air,  irri- 
tate the  extremities  of  the  nerves  of  tafte  and  fmell ;  which  ei- 
ther penetrate,  or  are  expanded  on  the  membranes  of  the  tongue 
and  noftrils-,  the  auditory  nerves  are  Simulated  by  the  vibra- 
tions of  the  atmofphere  communicated  by  means  of  the  tytnpa- 
num  and  of  the  fluid,  whether  of  air  or  of  water,  behind  it ;  and 
the  nerves  of  touch  by  the  hardnefs  of  furrounding  bodies, 
though  the  cuticle  is  interpofed  between  thefe  bodies  and  the 
medulla  of  the  nerve. 

As  the  nerves  of  the  fenfes  have  each  their  appropriated  ob- 
jedls,  which  (Itmulate  them  into  activity ;  fo  the  mufcular 
fibres,  which  are  the  terminations  of  other  fets  of  nerves,  have 
their  peculiar  objecls,  which  excite  them  into  aclion;  the  lon- 
gitudinal mufcles  are  Simulated  into  contraction  by  extenfion, 
whence  the  Sretching  or  pandiculation  after  a  long  continued 
pofture,  during  which  they  have  been  kept  in  a  date  of  exten- 
fion ;  and  the  hollow  mufcles  are  excited  into  action  by  diSen- 
tion,  as  thofe  of  the  rectum  and  bladder  are  induced  to  protrude 
their  contents  from  their  frnfe  of  the  diflention  rather  than  of 
the  acrimony  of  thofe  contents. 

There  are  other  objecls  adapted  to  Simulate  the  nerves, 
which  terminate  in  variety  of  membranes,  and  thoie  efpecially 
which  form  the  terminations  of  canals  ;  thus  the  preparations 
of  mercury  particularly  affect  the  falivary  glands,  ipecacuanha 
the  ftomach,  aloe  the  fphindter  of  the  anus,  cantharides  that  of 

the 


\ 


38  SENSORIAL  SECT.  XL  2.  i . 

the  bladder,  and  laftly  every  gland  of  the  body  appears  to  be  in- 
dued  with  a  kind  of  tafte,  by  which  it  felefts  or  forms  each  its 
peculiar  fluid  from  the  blood  j  and  by  which  it  is  irritated  into 
activity. 

Many  of  thefe  external  properties  of  bodies,  which  ftimulate 
our  organs  of  fenfe,  do  not  feem  to  affect  this  by  a  Tingle  im- 
pulfe,  but  by  repeated  impulfes  \  as  the  nerve  of  the  ear  is  prob- 
ably not  excitable  by  a  fingle  vibration  of  air,  nor  the  optic 
nerve  by  a  {ingle  particle  of  light ;  which  circumftance  produ- 
ces fome  analogy  between  thofe  two  fenfes,  at  the  fame  time 
the  folidity  of  bodies  is  perceived  by  a  fingle  application  of  a 
folid  body  to  the  nerves  of  touch,  and  that  even  through  the  cu- 
ticle -,  and  we  are  probably  poflefled  of  a  peculiar  fenfe  to  diftin- 
guifh  the  nice  degrees  of  heat  and  cold. 

The  fenfes  of  touch  and  of  hearing  acquaint  us  with  the  me- 
chanical impaft  and  vibration  of  bodies,  thofe  of  fmeli  and  tafte 
feem  to  acquaint  us  with  fome  of  their  chemical  properties, 
while  the  fenfes  of  vifion  and  of  heat  acquaint  us  with  the  ex- 
iftence  of  their  peculiar  fluids. 

Senfation  and  Volition. 

II.  Many  motions  are  produced  by  pleafure  or  pain,  and  that 
even  in  contradiction  to  the  power  of  volition,  as  in  laughing, 
or  in  the  ftrangury ;  but  as  no  name  has  been  given  to  pleafure 
or  pain,  at  the  time  it  is  exerted  fo  as  to  caufe  fibrous  motions, 
we  have  ufed  the  term  fenlatiofi  for  this  purpofe  ;  and  mean  it 
to  bear  the  fame  analogy  to  pleafure  and  pain,  that  the  word  vo- 
lition does  to  defire  and  averfion. 

j.  It  was  mentioned  in  the  fifth  Seftion,  that,  what  we  have 
termed  fenfation  is  a  motion  of  the  central  parts,  or  of  the  whole 
fenforium,  beginning  at  fome  of  the  extremities  of  it.  This  ap- 
pears fird,  becaufe  our  pains  and  pleafures  are  always  caufed  by 
our  ideas  or  mufcular  motions,  which  are  the  motions  of  the  ex- 
tremities of  the  fenforium.  And,  fecondly,  becaufe  the  fenfation 
of  pleafure  or  pain  frequently  continues  fome  time  after  the  ideas 
or  mufcular  motions  which  excited  it  have  ceafed  :  for  we  often 
feel  a  glow  of  pleafure  from  an  agreeable  reverie,  for  many  min- 
utes after  the  ideas,  that  were  the  fubje&  of  it,  have  efcaped 
our  memory  ;  and  frequently  experience  a  dejection  of  fpirits 
without  being  able  to  aflign  the  caufe  of  it  but  by  much  recol- 
lection. 

When  the  fenforial  faculty  of  defire  or  averfion  is  excited  fo 
as  to  caufe  fibrous  motions,  it  is  termed  volition  ;  which  is  faid 
in  Se£t.  V.  to  be  a  motion  of  the  central  parts  ;  or  of  the  whole 

fenforium, 


SECT.  XI.  2. 2.  ACTIONS.  39 

fenforium,  terminating  in  fome  of  the  extremities  of  it.  This 
appears,  firft,  becaufe  our  defires  and  averfions  always  terminate 
in  recollecting  and  comparing  our  ideas,  or  in  exerting  our  muf- 
cles ;  which  are  the  motions  of  the  extremities  of  the  fenforium. 
And,  fecondly,  becaufe  defire  or  averfion  begins,  and  frequently 
continues  for  a  time  in  the  central  parts  of  the  fenforium,  be- 
fore it  is  peculiarly  exerted  at  the  extremities  of  it ;  for  we 
fometimes  feel  defire  or  averfion  without  immediately  knowing 
their  objects,  and  in  confequence  without  immediately  exerting 
any  of  our  mufcular  or  fenfual  motions  to  attain  them  :  as  in  the 
beginning  of  the  pafTion  of  love,  and  perhaps  of  hunger,  or  in 
the  ennui  of  indolent  people. 

Though  fenfation  and  volition  begin  to  terminate  at  the  ex- 
tremities or  central  parts  of  the  fenforium,  yet  the  whole  of  it 
is  frequently  influenced  by  the  exertion  of  thefe  faculties,  as  ap- 
pears from  their  effects  on  the  external  habit :  for  the  whole 
Ikin  is  reddened  by  (hame,  and  an  univerfal  trembling  is  pro- 
duced by  fear  :  and  every  mufcle  of  the  body  is  agitated  in  an- 
gry people  by  the  defire  of  revenge. 

There  is  another  very  curious  circumflance,  which  (hews  that 
fenfation  and  volition  are  movements  of  the  fenforium  in  con- 
trary directions  ;  that  is,  that  volition  begins  at  the  central  parts 
of  it,  and  proceeds  to  the  extremities  ;  and  that  fenfation  begins 
at  the  extremities  and  proceeds  to  the  central  parts  :  I  mean 
that  thefe  two  fenforial  faculties  cannot  be  ftrongly  exerted  at 
the  fame  time  \  for  when  we  exert  our  volition  flrongly,  we  do 
not  attend  to  pleafure  or  pain  ;  and  converfely,  when  \ve  are 
ilrongly  affected  with  the  fenfation  of  pleafure  or  pain,  we  ufe 
no  volition.  As  will  be  further  explained  in  Section  XVIII. 
on  fleep,  and  Section  XXXIV.  on  volition. 

2.  All  our  emotions  and  pafiions  feem  to  arife  out  of  the  ex- 
ertions of  thefe  two  faculties  of  the  animal  fenforium.  Pride, 
hope,  joy,  are  the  names  of  particular  pleafures  :  fhame,  defpair, 
forrow,  are  the  names  of  peculiar  pains  :  and  love,  ambition, 
avarice,  of  particular  defires  :  hatred,  difguft,  fear,  anxiety,  of 
particular  averfions.  Whilft  the  paffion  of  anger  includes  the 
pain  from  a  recent  injury,  and  the  averfion  to  the  adverfary  that 
occafioned  it.  And  cotnpaflion  is  the  pain  we  experience  at 
the  fight  of  mifery,  and  the  defire  of  relieving  it. 

There  is  another  tribe  of  defires,  which  is  commonly  term- 
ed appetites,  and  are  the  immediate  confequences  of  the  abfence 
of  iome  irritative  motions.  Thofe,  which  arife  from  defect  of 
internal  irritations,  have  proper  names  conferred  upon  them,  as 
hunger,  thirft,  luft,  and  the  defire  of  air,  when  our  refpiration  is 
impaired  by  noxious  vapours  5  and  of  warmth,  when  we  are 

expofed 


40  SENSORI AL  SECT.  XI.  2. 3 . 

expofed  to  too  great  a  degree  of  cold.  But  thofe,  whofe  ftimu- 
li  are  external  to  the  body,  are  named  from  the  objects,  which 
are  by  nature  conftituted  to  excite  them  ;  thefe  defires  originate 
from  our  paft  experience  of  the  pleafurable  fenfations  they  oc- 
cafion,  as  the  fmell  of  a  hyacinth,  or  the  tafte  of  a  pine  apple. 

Whence  it  appears  that  our  pleafures  and  pains  are  at  lead 
as  various  and  as  numerous  as  our  irritations ;  and  that  our  de- 
fires  and  averfions  muft  be  as  numerous  as  our  pleafures  and 
pains.  And  that  as  fenfation  is  here  ufed  as  a  general  term  for 
our  numerous  pleafures  and  pains,  when  they  produce  the  con- 
tractions of  our  fibres  ;  fo  volition  is  the  general  name  for  our 
defires  and  averfions,  when  they  produce  fibrous  contractions. 
Thus,  when  a  motion  of  the  central  parts,  or  of  the  whole  fenfo- 
rium,  terminates  in  the  exertion  of  our  mufcles,  it  is  generally 
called  voluntary  action  ;  when  it  terminates  in  the  exertion  of 
our  ideas,  it  is  termed  recolle£tion,  reafoning,  determining. 

3.  As  the  fenfations  of  pleafure  and  pain  are  originally  in- 
troduced by  the  irritations  of  external  objects  :  fo  our  defires 
and  averfions  are  originally  introduced  by  thofe  fenfations  ;  for 
when  the  objects  of  our  pleafures  or  pains  are  at  a  diltance, 
and  we  cannot  inftantaneoufly  poffefs  the  one,  nor  avoid  the  oth- 
er, then  defire  or  averfion  is  produced,  and  a  voluntary  exertion 
of  our  ideas  or  mufcles  fucceeds. 

The  pain  of  hunger  excites  you  to  look  out  for  food,  the  tree 
that  (hades  you  prefents  its  odoriferous  fruit  before  your  eyes, 
you  approach,  pluck,  and  eat. 

The  various  movements  of  walking  to  the  tree,  gathering  the 
fruit,  and  malticating  it,  are  affociated  motions  introduced  by 
their  connexion  with  fenfation ;  but  if  from  the  uncommon 
height  of  the  tree,  the  fruit  be  inacceflible,  and  you  are  prevent- 
ed from  quickly  pofleffing  the  intended  pleafure,  defire  is  produ- 
ced. The  confequence  of  this  defire  is,  firft,  a  deliberation  a* 
bout  the  means  to  gain  the  object  of  pleafure  in  proceis  of  time, 
as  it  cannot  be  produced  immediately  ;  and,  fecondly,  the  muf- 
cular  action  necefiary  for  this  purpofe. 

You  voluntarily  call  up  all  your  ideas  of  caufation,  that  are 
related  to  the  effect  you  defire,  and  voluntarily  examine  and 
compare  them,  and  at  length  determine  whether  to  afcend  the 
tree,  or  to  gather  ftones  from  the  neighbouring  brook,  is  eafier 
to  praclife,  or  more  promifing  of  fuccefs  ;  and,  finaJly,  you 
gather  the  ftones,  and  repeatedly  fling  them  to  diflodge  the  fruit. 

Hence  then  we   gain  a  criterion  to  diftinguifh  voluntary  acts 
cr  thoughts  from  thofe  caufed  by  fenfation.     As  the  former  are 
always  employed  about  the  means  to  acquire  pleafurable  objects, 
©r  the  means  to  avoid  painful  ones  \  while  the  latter  are  em- 
ployed 


SECT.  XI.  2. 4.  ACTIONS.  41 

ployed  in  the  poncfiion  of  thofe,  which  are  already  in  our 
power. 

Hence  the  aftinty  of  this  power  of  volition  produces  the 
great  difference  between  the  human  and  the  brute  creation. 
The  ideas  and  the  actions  of  brutes  are  alrnofl  perpetually  em- 
ployed about  their  prefent  pleafures,  or  their  prefent  pains  ;  and, 
except  in  the  few  inftances  which  are  mentioned  in  Section 
XVI.  on  inftintf,  they  feldom  bufy  themfelves  about  the  means 
of  procuring  future  blifs,  or  of  avoiding  future  mifery  ;  fo  that 
the  accquiring  of  languages,  the  making  of  to^ls,  and  labouring 
for  money,  which  are  all  only  the  means  to  procure  pleafures  ; 
and  the  praying  to  the  Deity,  as  another  means  to  procure  hap- 
•pinefs,  are  characleriflic  of  human  nature. 

4.  As  there  are  many  difeafes  produced  by  the  quantity  of 
the  fenfation  of  pain  or  pleafure  being  too  great  or  too  little  ;  fo 
are  there  difeafes  produced  by  the  fufceptibility  of  the  conftitu- 
tion  to  motions  cauiabie  by  thefe  fenfations  being  too  dull  or  too 
vivid.  This  fufceptibility  of  the  fyftem  to  fenfitive  motions  is 
termed  fe-nfibility,  to  diftinguifh  it  from  fenfation,  which  is  the 
actual  exiftence  or  exertion  of  pain  or  pleafure. 

Other  clafTes  of  difeafes  are  owing  to  the  exceflive  prompti- 
tude, or  fluggimnefs  of  the  conftitution  to  voluntary  exertions, 
as  well  as  to  the  quantity  of  defire  or  of  averfion.  This  fuf- 
ceptibility of  the  fyftem  to  voluntary  motions  is  termed  volun- 
tarity,  to  diftinguilh  it  from  volition,  which  is  the  exertion  of 
defire  or  averfion  ;  thefe  difeafes  will  be  treated  of  at  length  in 
the  progrefs  of  the  work. 

AJJo  elation. 

III.  i .  It  is  not  eafy  to  afllgn  a  caufe,  why  thofe  animal  move- 
ments, that  have  once  occurred  in  fucceflion,  or  in  combination, 
fhould  afterwards  have  a  tendency  to  fucceed  or  accompany 
each  other.  It  is  a  property  of  animation,  and  diftinguilhes  this 
order  of  being  from  the  other  productions  of  nature. 

When  a  child  firft  wrote  the  word  man,  it  was  diftinguifhed 
in  his  mind  into  three  letters,  and  thofe  letters  into  many  parts 
of  letters  ;  but  by  repeated  ufe  the  word  man  becomes  to  his 
hand  in  writing  it,  as  to  his  organs  of  fpeech  in  pronouncing  it, 
but  one  movement  without  any  deliberation,  or  fenfation,  or  ir- 
ritation, interpofed  between  the  parts  of  it.  And  as  many  fep- 
arate  motions  of  our  mufcles  thus  become  united,  and  form,  as 
it  were,  one  motion  ;  fo  each  feparate  motion  before  fuch  union 
may  be  conceived  to  confift  of  many  parts  or  fpaces  moved 
through  ;  and  perhaps  even  the  individual  fibres  of  our  mufcles 

VOL.  I.  G  have 


42  SENSORIAL  ACTIONS.     SECT.  XL  3.  2* 

have  thus  gradually  been  brought  to  aft  in  concert,  which  hab- 
its began  to  be  acquired  as  early  as  the  very  formation  of  the 
moving  organs,  long  before  the  nativity  of  the  animal ;  as  ex- 
plained in  the  Section  XVI.  2.  on  inftinct. 

2.  There  are  many  motions  of  the  body,  belonging  to  the  ir- 
ritative clafs,  which  might  by  a  hafty  obferver  be  miftaken  for 
aflbciated  ones  ;  as  the  periftaltic  motion  of  the  ftomach  and  in- 
teftines,  and  the  contractions  of  the  heart  and  arteries,  might  be 
fuppofed  to  be  affbciated  with  the  irritative  motions  of  their 
nerves  of  fenfe,  rather  than  to  be  excited  by  the  irritation  of 
their  mufcular  fibres  by  the  diftention,  acrimony,  or  momentum 
of  the  blood.  So  the  diftention  or  elongation  of  mufcles  by  ob- 
jects external  to  them  irritates  them  into  contraction,  though 
the  cuticle  or  other  parts  may  intervene  between  the  ftimulating 
body  and  the  contracting  mufcle.  Thus  a  horfe  voids  his  ex- 
crement when  its  weight  or  bulk  irritates  the  rectum  or  fphinc- 
ter  ani.  Thefe  mufcles  act  from  the  irritation  of  diftention, 
when  he  excludes  his  excrement,  but  the  mufcles  of  the  abdo- 
men and  diaphragm  are  brought  into  motion  by  affociation  with 
thofe  of  the  fphinder  and  rectum. 


SECT. 


SECT.  XII.  OF  STIMULUS,  &c.  43 


SECT.       XII. 

OF   STIMULUS,    SENSORIAL    EXERTION,    AND    FIBROUS    CONTRAC- 
TION. 

I.  Of  fibrous  contraction.  I.  Two  particles  of  a  fibre  cannot 
approach  without  the  intervention  of  fomething,  as  in  magnet  ifm, 
elecJricity,  elajlicity.  Spirit  of  life  is  not  eleclric  ether.  Galvanfs 
experiments.  2.  Contraction  of  a  fibre.  3.  Relaxation  fuc- 
ceeds.  4.  SucceJJive  contractions^  'with  intervals.  £hnck  pulfe 
from  debility,  from  paucity  of  blood.  Weak  contraElions  perform- 
ed in  lefs  time,  and  with  JJjorter  intervals.  5 .  Laft  fitua- 
tion  of  the  fibres  continues  after  contraction.  6.  Contraction 
greater  than  ufual  induces  pleafure  or  pain.  7.  Mobility  of  the 
fibres  uniform.  Quantity  of  fenforial  power  fluBuates.  Conjli- 
tutes  excitability. — II.  Of  fenibrial  exertion.  i.  Animal  motion 
includes  fiimulus,  fenforial  pow  er,  and  contractile  fibres.  *The  fen- 
forial faculties  aft  feparately  or  conjointly.  Stimulus  of  four  kinds. 
Strength  and  weaknefs  defined.  Senforial  power  perpetually  ex- 
haujled  and  renewed.  Weaknefs  from  defecJ  ofjiimulus.  From 
defecl  of  fenforial  power,  the  direCt  and  indirecl  debility  of  Dr. 
Brown.  Why  we  become  warm  in  Buxton  bath  after  a  time,  and 
fee  well  after  a  time  in  a  darkijjj  room.  Fibres  may  aCt  violently, 
or  with  their  whole  force ,  and  yet  feebly.  Great  exertion  in  in- 
flammation explained  Great  mufcular  force  of  fome  infane  peo- 
ple. 2.  Occafional  accumulation  of  fenforial  power  in  mufclesfub- 
jeCt  to  conjlcintjlimulus.  In  animals  flee  ping  in  'winter.  In  eggs, 
feeds y  f chirr hous  tumours,  tendons,  bones.  3.  Great  exertion  in- 
troduces pleafure  or  pain.  Inflammation.  Libration  of  the  fyf- 
tem  between  torpor  and  aCtivity.  Fever- fits.  4.  Defire  and  a- 
verfion  introduced.  Excefs  of  volition  cures  fevers. — III.  Of  re- 
peated dim  ulus.  J.  A  jlitnulus  repeated  too  frequently  lofes  ef- 
feCt.  As  opium,  wine,  grief.  Hence  old  age.  Opium  and  aloes 
in  fmall  dofes -  2.  AJlimulusnot  repeated  infrequently  does  not 
lofe  effecJ.  Perpetual  movement  of  the  vital  organs.  3.  A  Jlim- 
ulus  repeated  at  uniform  times  produces  greater  fjfeft.  Irrita- 
tion combined  'with  ajfociation.  4.  A  flimulus  repeated  frequent- 
ly and  uniformly  may  be  withdrawn,  and  the  aclion  of  the  organ 
will  continue.  Hence  the  bark  cures  agues,  andflrengthens  weak 
coujlitutions.  5,  Defecl  of  Jlimulus  repeated  at  certain  intervals 
amfes  fever-fits.  6.  Stimulus  hng  applied  ceafes  to  ccl  a  ft: con d 
time.  7  If  aflimulus  excites  fetifation  in  an  organ  not  ujually 
'•tidintofenfatton,  inflammation  is  produced. — IV.  Of  ftimu- 
'  \'-\  than  natural,  i.  A  Jlimulus  grenter  than  natural 

di minifies* 


44  OF  STIMULUS  SECT.  XII.  i.  i. 

diminijhes  the  quantity  of  fenforial  power  in  general.  2.  ///  par- 
ticular organs.  3.  Induces  the  organ  into  f pa f mo  die  aclions.  4. 
Induces  the  antagonift  fibres  into  aElion.  5.  Induces  the  organ  in- 
to convulftve  or  fixed  fpaftns.  6.  Produces  paralysis  of  the  or- 
gan.— V.  Of  ftimulus  lefs  than  natural,  i.  Stimulus lefs  than 
natural  occnfions  accumulation  of  fenforial power  in  general.  2. 
In  particular  organs  ^flufe'ing  of  the  face  in  a  frojly  morning*  In 
fibres  fubjecJ  to  perpetual  Jlimulus  only.  Quantity  of  Jenforial 
power  inverfely  as  the  Jlimulus.  3.  Induces  pain.  As  of  cold > 
hunger^  headach.  4.  Induces  more  feeble  and  frequent  contrac- 
tions. As  in  low  fevers.  Which  are  frequently  owing  to  deficien- 
cy of  fenforial  power  rather  than  to  deficiency  of  Jlimulus.  5.  In- 
verts JiicceJJroe  trains  of  motion.  Inverts  ideas.  6.  Induces  pa- 
ralyfis  and  death. — VI.  Cure  of  increafed  exertion,  i,  Nat- 
itral  cure  of  exhaujlion  of  fenforial  power.  2.  Dvcreafe  the  irri- 
tations. Venefetfion.  Cold.  Abjlinence.  3.  Prevent  the  pre- 
vious cold  fit.  Opium.  Bark.  Warmth.  Anger.  Surprife. 
4.  Excite  fome  other  part  of  the  fyjlem  Opium  and  warm  bath 
relieve  pains  both  from  defecl  and  from  excefs  of  Jlimulus.  5. 
Firft  increafe  the  Jlimulus  above,  and  then  decreafe  it  beneath  the 
natural  quantity. — VII.  Cure  of  decreafed  exertion,  i.  Nat- 
ural cure  by  accumulation  of  fenforial  power.  Ague-fits.  Synco- 
pe. 2.  Increafe  tkejiimulation^  by  wine>  opiumy  given  fo  as  not  to 
intoxicate.  Cheerful  ideas.  3.  Change  the  kinds  of  Jlimulus. 
4.  Stimulate  the  affociated  organs.  B lifters  of  ufe  in  heart-burn, 
and  cold  extremities.  5.  Decreafe  thejlimulationfor  a  time,  cold 
bath.  6.  Decreafe  the  Jlimulation  below  natural \  and  then  in- 
creafe  it  above  natural.  Bark  after  emetics.  Opium  after  vene- 
J'ecJion.  Praclice  of  Sydenham  in  chlorofis.  7.  Prevent  unnecef- 
Jary  expenditure  of  fenforial  power.  Decumbent  pofture^  filencey 
darknefs.  Pulfe  quickened  by  rifing  out  of  bed.  8.  "To  the  great- 
efl  degree  of  quie/'cence  apply  the  leajl  flimulus.  Other  wife  pa- 
ralyfis  or  inflammation  of  the  organ  e fifties.  '  Gin>  wine,  biiflers^ 
dejlroy  by  too  great  Jlimulation  in  fevers  with  debility.  Intoxica- 
tion in  thejlightej[  degree  fucceeded  by  debility.  Golden  rule  for 
determining  the  befl  degree  of  flimulus  in  low  fevers.  Another 
golden  rule  for  determining  the  quantity  of  fpirit  which  thofet  who 
are  debilitated  by  drinking  ity  may  fafdy  omit. — VIII.  Conclufan* 
Somejtirnuli  increafe  the  producHon  of  fenforial  power* 

I.   Of  fibrous  contractions. 

i.  IF  two  particles  of  iron  lie  near  each  other  without  mo- 
tion, and  afterwards  approach  each  ether ,  it  is  reafonable  to 
conclude  that  fomethhig  bcfides  th^  iron  panicles  is  the  caufe  of 

their 


SECT.  XII.  i.  i.          AND  EXERTION.  45 

their  approximation  ;  this  invisible  fomething  is  termed  magnet- 
ifm.  In  the  fame  manner,  if  the  particles,  which  compofe  an 
animal  mufcle,  do  not  touch  each  other  in  the  relaxed  ftate  of 
the  mufcle,  and  are  brought  into  contact  during  the  contraction 
of  the  mufcle,  it  is  reafonable  to  conclude,  that  fome  other 
agent  is  the  caufe  of  this  new  approximation.  For  nothing  can 
atf>  where  it  does  not  exifl  ;  for  to  aft  Includes  to  exift ;  and  there- 
fore the  particles  of  the  mufcular  fibre  (which  in  its  (late  of  re» 
laxation  are  fuppofed  not  to  touch)  cannot  effect  each  other 
without  the  influence  of  fome  intermediate  agent ;  this  agent  is 
here  termed  the  fpirit  of  animation,  or  fenforial  power,  but  may 
with  equal  propriety  be  termed  the  power,  which  caufes  con- 
traction ;  or  may  be  called  by  any  other  name,  which  the  reader 
may  choofe  to  aifix  to  it. 

The  contraction  of  a  mufcular  fibre  may  be  compared  to  the 
following  electric  experiment,  which  is  here  mentioned  not  as 
a  philofophical  analogy,  but  as  an  illuflration  or  fimile  to  facil- 
itate the  conception  of  a  difficult  fubject%  Let  twenty  very  fmall 
Leyden  phials  properly  coated  be  hung  in  a  row  by  fine  filk 
threads  at  a  fmall  diftance  from  each  other ;  let  the  internal 
charge  of  one  phial  be  pofitive,  and  of  the  other  negative  alter- 
nately, if  a  communication  be  made  from  the  internal  furface  of 
the  firft  to  the  external  furface  of  the  laft  in  the  row,  they  will 
all  of  them  inllantly  approach  each  other,  and  thus  (horten  a  line 
that  might  connect  them  like  a  mufcular  fibre.  See  Botanic 
Garden,  P.  I.  Canto  1. 1.  202.  note  on  Gymnotus. 

The  attractions  of  electricity  or  of  magnetifm  do  not  apply 
philofophically  to  the  illufiration  of  the  contraction  of  animal 
fibres,  fince  the  force  oi  thofe  attractions  increafes  in  fome  pro- 
portion inverfcly  as  the  diftance,  but  in  mufcular  motion  there 
appears  no  difference  in  velocity  or  ftrength  during  the  begin- 
ning or  end  of  the  contraction,  but  what  may  be  clearly  afcribed 
to  the  varying  mechanic  advantage  in  the  approximation  of  one 
bone  to  another.  Nor  can  mufcular  motion  be  affimilated  with 
greater  plaufibility  to  the  attraction  of  cohefion  or  elafticity  ;  for 
in  bending  a  fleel  fpring,  as  a  fmall  fvvord,  a  lefs  force  is  re- 
quired to  bend  it  the  firil  inch  than  the  fecond  ;  and  the  fecond 
than  the  third  j  the  particles  of  fleel  on  the  convex  fide  of  the 
bent  fpring  endeavouring  to  reftore  themfelves  more  powerfully 
the  further  they  are  drawn  from  each  other.  See  Botanic  Gar- 
den, P.  I.  addit.  Note  XVIII. 

I  am  aware  that  this  may  be  explained  another  way,  by  fup~ 
pofing  the  elafticity  of  the  fpring  to  depend  more  on  the  com- 
prefiion  of  the  particles  on  die  concave  iide  than  on  the  trxten- 
fion  of  them  on  the  convex  fulc  \  and  by  fuppofing  the  elaiiicity 

of  ' 


4«  OF  STIMULUS  SECT.  XII.  1.2, 

of  the  elaftic  gum  to  depend  more  on  the  refiftance  to  the  lateral 
comprelTion  of  its  particles  than  to  the  longitudinal  extcnfion  of 
them.  Neverthelefs  in  mufcular  contraction,  as  above  obferv- 
ed,  there  appears  no  difference  in  the  velocity  or  force  of  it  at 
its  commencement  or  at  its  termination  j  from  whence  we  mull 
conclude  that  animal  contraction  is  governed  by  laws  of  its  own, 
and  not  by  thofe  of  mechanics,  chemiilry,  magnetifm,  or  elec- 
tricity. 

On  thele  accounts  I  do  not  think  the  experiments  conclufive, 
which  were  lately  pubiifhed  by  Galvani,  Volta,  and  others,  to 
{hew  a  ilmilitude  between  the  fpirit  of  animation,  which  con- 
trafts  the  mufcular  fibres,  and  the  eledric  fluid.  Since  the 
eledlric  fluid  may  a£t  only  as  a  more  potent  itimulus  exciting 
the  mufcular  fibres  into  action,  and  not  by  fupplying  them  with 
a  new  quantity  of  the  fpirit  of  life.  Thus  in  a  recent  hemiple- 
gia  I  have  frequently  obferved,  when  the  patient  yawned  and 
itretched  himfeif,  that  the  paralvtic  limbs  moved  alfo,  though 
they  were  totally  difobedient  to  the  will.  And  when  he  was 
electrified  by  palling  (hocks  from  the  affected  hand  to  the  affedt- 
ed  foot,  a  motion  of  the  paralytic  limbs  was  alfo  produced.  Now 
as  in  the  a£t  of  yawning  the  mufcles  of  the  paralytic  limbs  were 
excited  into  action  by  the  ftimulus  of  the  irkfomenefs  of  a  con- 
tinued pofture,  and  not  by  any  additional  quantity  of  the  fpirit 
of  life  ;  fo  we  may  conclude,  that  the  paffuge  of  the  eledtrk:  flu- 
id, which  produced  a  fimilar  effect,  adted  only  as  a  llimulus, 
and  not  by  fupplying  any  addition  of  fenforial  power. 

If  neverthelefs  this  theory  fhould  ever  become  eftablifhed,  a 
ftimulus  mult  be  called  an  edudor  of  vital  ether  •,  which  ftim- 
ulus may  confift  of  fen  fat  ion  or  volition,  as  in  the  electric  eel,  as 
well  as  in  the  appulfes  of  external  bodies ;  and  by  drawing  off 
the  charges  of  vital  fluid  may  occafion  the  contraction  or  mo- 
tions of  the  mufcular  fibres,  and  organs  of  fenfe. 

2.  The  immediate  effort  of  the  adlion  of  the  fpirit  of  anima- 
tion or  fenforial  power  on  the  fibrous  parts  of  the  body;  whether 
it  a<5ts  in  the  mode  of  irritation,  fenfation,  volition,  or  affocia- 
tion,  is  a  contraction  of  the  animal  fibre,  according  to  the  fec- 
ond  law  of  animal  caufation.  Seft.  IV.  Thus  the  ftimulus  of 
the  blood  induces  the  contraction  of  the  heart ;  the  agreeable 
tafte  of  a  ftrawberry  produces  the  contraction  of  the  mufcles  of 
deglutition ;  the  effort  of  the  will  contra£ts  the  mufcles,  which 
move  the  limbs  in  walking  j  and  by  affociation  other  mufcles  or 
the  trunk  are  brought  into  contraction  to  preferve  the  balance 
of  the  body.  The  fibrous  extremities  of  the  organs  of  fenfe 
have  been  ihewn,  by  the  ocular  fpeftra  in  Sect.  III.  to  fuffer 

fimilar 


SECT.  XIL  i ,  3.        AND  EXERTION.  47 

fimilar  contraction  by  each  of  the  above  modes  of  excitation  ; 
and  by  their  configurations  to  conftitute  our  ideas. 

3.  After  animal  fibres  have  for  fome  time  been  excited  into 
contraction,  a  relaxation  fucceeds,  even  though  the  exciting 
caufe  continues  to  act.  In  refpecl  to  the  irritative  motions  this 
is  exemplified  in  the  periftaltic  contractions  of  the  bowels ; 
which  ceafe  and  are  renewed  alternately,  though  the  ftimulus  of 
the  aliment  continues  to  be  uniformly  applied  ;  in  the  fenfitive 
motions,  as  in  ftrangury,  tenefmus,  and  parturition,  the  alter- 
nate contractions  and  relaxations  of  the  mufcles  exift,  though 
the  ftimulus  is  perpetual.  In  our  voluntary  exertions  it  is  expe- 
rienced, as  no  one  can  hang  long  by  the  hands,  however  vehe- 
mently he  wills  fo  to  do ;  and  in  the  aflbciate  motions  the  con- 
firm change  of  our  attitudes  evinces  the  neceflity  of  relaxation 
to  thole  mu Teles,  which  have  been  long  in  action. 

This  relaxation  of  a  mufcle  after  its  contraction,  even  though 
the  ftimulus  continues  to  be  applied,  appears  to  arife  from  the 
expenditure  or  diminution  of  the  fpirit  of  animation  previoufly 
refusent  in  the  mufcle,  according  to  the  fecond  law  of  animal 
caufation  in  Seel:.  IV.  In  thole  conftitutions,  which  are  termed 
weak,  the  fpirit  of  animation  becomes  looner  exhaufted,  and 
tremulous  motions  are  produced,  as  in  the  hands  of  infirm  peo- 
ple, when  they  lift  a  cup  to  their  mouths.  This  quicker  ex- 
hauftion  of  the  fpirit  of  animation  is  probably  owing  to  a  lefs 
quantity  of  it  refiding  in  the  acting  fibres,  which  therefore  more 
frequently  require  a  fupply  from  the  nerves,  which  belong  to 
them 

4  If  the  fenforial  power  continues  to  aft,  whether  it  arts  in 
the  mode  of  irritation,  fenfation,  volition,  or  afTociation,  a  new 
contraction  of  the  animal  fibre  fucceeds  after  a  certain  interval ; 
which  interval  is  of  (horter  continuance  in  weak  people  than  in 
ftrong  ones.  '1  his  is  exemplified  in  the  (baking  of  the  hands  of 
weak  people,  when  they  attempt  to  write.  In  a  manufcript  epif- 
tle  of  one  of  my  correfpondents,  which  is  written  in  a  fmall 
hand,  I  obferve  from  four  to  fix  zigzags  in  the  perpendicular 
ftroke  of  every  letter,  which  (hews  that  both  the  contractions  of 
the  fingers,  and  intervals  between  them,  muft  have  been  per- 
formed in  very  fhort  periods  of  time. 

The  times  of  contraction  of  the  mufcles  of  enfeebled  people 
being  lefs,  and  the  intervals  between  thofe  contractions  being 
lefs  alfo,  accounts  for  the  quick  pulfe  in  fevers  with  debility, 
and  in  dying  animals.  The  fhortnefs  of  the  intervals  between 
one  contraction  and  another  in  weak  conftitutions,  is  probably 
owing  to  the  general  deficiency  of  the  quantity  of  the  fpirit  of 
animation,  and  that  therefore  there  is  a  lefs  quantity  of  it  to  be 

received 


4  8  OF  STIMULUS  SECT.  XII.  i.  4. 

received  at  each  interval  of  the  aftivity  of  the  fibres.  Hence  in 
repeated  motions,  as  of  the  fingers  in  performing  on  the  harpfi- 
chord,  it  would -at  firft  fight  appear,  that  fwiftnefsand  ftrength 
were  incompatible  :  nevertheless  the  (ingle  contraction  of  a  muf- 
cle  is  performed  with  greater  velocity,  as  well  as  with  greater 
force  by  vigorous  confHtutions,  as  in  throwing  a  javelin. 

There  is  however  another  circumftance,  which  may  often 
contribute  to  caufe  the  quicknefs  of  the  pulfe  in  nervous  fevers, 
as  in  animals  bleeding  to  death  in  the  flaughter-houfe  ;  which  is 
the  deficient  quantity  of  blood,  whence  the  heart  is  but  half 
diftended,  and  in  confequence  fooner  contracts.  See  Se£t 
XXXII.  2.  i. 

For  we  mud  not  confound  frequency  of  repetition  with 
quicknefs  of  motion,  or  the  number  of  puifations  with  the  ve- 
locity, with  which  the  fibres,  which  conftitute  the  coats  of  the 
arteries,  contract  themfelves.  For  where  the  frequency  of  the 
puifations  is  but  feventy-five  in  a  minute,  as  in  health  ;  the  con- 
tracting fibres,  which  conftitute  the  fides  of  the  arteries,  may 
move  through  a  greater  fpace  in  a  given  time,  than  where  the 
frequency  of  pulfation  is  one  hundred  and  fifty  in  a  minute,  as 
in  fome  fevers  with  great  debility.  For  if  in  thofe  fevers  the 
arteries  do  not  expand  themfelves  in  their  diaflole  to  more  than 
half  the  ufual  diameter  of  their  diaftole  in  health,  the  fibres 
which  conftitute  their  coats,  will  move  through  a  lefs  fpace  in 
a  minute  than  in  health,  though  they  make  two  puifations  for 
one. 

Suppofe  the  diameter  of  the  artery  during  its  fyftole  to  be 
one  line,  and  that  the  diameter  of  the  fame  artery  during  its  di- 
aftole is  in  health  four  lines,  and  in  a  fever  with  great  debility 
only  two  lines.  It  follows  that  the  arterial  fibres  contract  in 
health  from  a  circle  of  twelve  lines  in  circumference  to  a  circle 
of  three  lines  in  circumference,  that  is,  they  move  through  a  fpace 
of  nine  lines  in  length.  While  the  arterial  fibres  in  the  fever 
with  debility  would  twice  contract  from  a  circle  of  fix  lines  to  a 
circle  of  three  lines  ;  that  is,  while  they  move  through  a  fpace 
equal  to  fix  lines.  Hence  though  the  frequency  of  pulfation 
in  fever  be  greater  as  two  to  one,,  yet  the  velocity  of  contrac- 
tion in  health  is  greater  as  nine  to  fix,  or  as  three  to  two. 

On  the  contrary,  in  inflammatory  difeafes  with  ftrength,  as  in 
the  pleurify,  the  velocity  of  the  contracting  fides  of  the  arteries 
5s  much  greater  than  in  health  :  for  if  we  fuppofe  the  number  of 
puifations  in  a  pleurify  to  be  half  as  much  more  than  in  health, 
that  is,  as  one  hundred  and  twenty  to  eighty,  (which  is  about 
what  generally  happens  in  inflammatory  difeafes)  and  if  the  di- 
ameter of  the  artery  in  diaftole  be  one  third  greater  than  in 

health, 


SECT.  XII.  i.  5.        AND  EXERTION.  49 


health,  which  I  believe  is  near  the  truth,  the  refult  will  be,  that 
the  velocity  of  the  contraCtile  fides  of  the  arteries  will  be  in  a 
pleurify  as  two  and  a  half  to  one,  compared  to  the  velocity  of 
their  contraction  in  a  ftate  of  health  ;  for  if  the  circumference 
of  the  fyftole  of  the  artery  be  three  lines,  and  the  diaftole  in 
health  be  twelve  lines  in  circumference,  and  in  a  pleurify 
eighteen  lines  ;  and  fecondly,  if  the  artery  pulfates  thrice  in  the 
difeafed  (late  for  twice  in  the  healthy  one,  it  follows,  that  the 
velocity  of  contraction  in  the  difeafed  (late  to  that  in  the  healthy 
ftate  will  be  forty-five  to  eighteen,  or  as  two  and  a  half  to  one. 
From  hence  it  would  appear,  that  if  we  had  a  criterion  to  de- 
termine the  velocity  of  the  arterial  contractions,  it  would  at  the 
fame  time  give  us  their  ftrength,  and  thus  be  of  more  fervice  in 
diftinguifhing  difeafes,  than  the  knowledge  of  their  frequency. 
As  fuch  a  criterion  cannot  be  had,  the  frequency  of  pulfation, 
the  age  of  the  patient  being  allowed  for,  will  in  fome  meafure 
afliit  us  to  diitinguifh  arterial  ftrength  from  arterial  debility, 
fince  in  inflammatory  difeafes  with  ftrength  the  frequency  fel- 
dom  exceeds  one  hundred  and  eighteen  or  one  hundred  and 
twenty  puiiations  in  a  minute  ;  unlefs  under  fome  peculiar  cir- 
cumftance,  as  the  great  additional  ftimuli  of  wine  or  of  exter- 
nal heat. 

5.  After  a  mufcle  or  organ  of  fenfe  has  been    excited   into 
contraction,  and  the  fenforial  power  ceafes  to  aCt,  the  laft  fitua- 
tion  or  configuration  of  it   continues  ;  unlefs  it  be  difturbed  by 
the  aCtion  of  fome  antagonift  fibres,  or  other  extraneous  power. 
Thus   in   weak  or  languid    people,   wherever  they  throw  their 
limbs  on  rheir  bed  or  fofa,    there  they  lie,    till  another  exertion 
changes  their  attitude  ;  hence  one  kind  of  ocular  fpectra   feems 
to  be   produced  after  looking  at  bright  objects  ;  thus  when  a 
fire-ftick  is  whirled  round  in  the  night,  there  appears  in  the  eye 
a  complete  circle  of  fire  ;  the   aCticn   or  configuration  of  one 
part  of  the  retina  not  ceafing  before  the  return  of  the  whirling 
lire. 

Thus  if  any  one  looks  at  the  fetting  fun  for  a  (hort  time,  and 
then  covers  his  clofed  eyes  with  his  hancl,  he  will  for  many  fec- 
onds  of  time  perceive  the  image  of  the  fun  on  his  retina.  A 
fimiiar  image  of  all  other  bodies  would  remain  fome  time  in  the 
eye,  but  is  effaced  by  the  eternal  change  of  the  motions  of  the 
extremity  of  this  nerve  in  our  attention  to  other  objects.  See 
SeCt.  XVII.  i.  3.  on  Sleep.  Hence  the  dark  fpots  and  other 
ocular  ipeCtra,  are  more  frequently  attended  to,  and  remain 
longer  in  the  eyes  of  weak  people,  as  after  violent  exercife,  in- 
toxication, or  want  of  ileep. 

6.  A  contraction  of  the  fibres  fornewhat  greater   than  ufual 
VOL.  I.  H  introduces, 


5*  OF  STIMULUS          SECT.  XII.  i.  7. 

introduces  pleafurable  fenfation  into  the  fyftem,  according  to  the 
fourth  law  of  animal  caufation.  Hence  the  pleafure  in  the  be- 
ginning of  druukennefs  is  owing  to  the  increafed  action  of  the 
fyftem from  the  Itimulus  of  vinous  fpirit  or  of  opium.  If  the 
contractions  be  (till  greater  in  energy  or  duration,  painful  fen~ 
fations  are  introduced,  as  in  confequence  of  great  heat,  or  cauf- 
tic  applications  or  fatigue. 

If  any  part  of  the  fyftem,  which  is  ufed  to  perpetual  a&ivity, 
as  the  ftomach,  or  h^art,  or  the  fine  veflels  of  the  fkin,  acts  for  a 
time  with  lefs  energy,  another  kind  of  painful  fenfation  enfues, 
which  is  called  hunger,  or  faintnefs,  or  cold.  This  occurs  in  a 
lefs  degree  in  the  locomotive  mufcles,  and  is  called  wearifome- 
nefs.  In  the  two  former  kinds  of  fenfation  there  is  an  expendi- 
ture of  fenforial  power,  in  the  latter  there  is  an  accumulation 
of  it. 

7.  We  have  ufed  the  words  exertion  of  fenforial  power  as  a 
general  term  to  exprefs  either  irritation,  fenfation,  volition,  or 
aflbciation  ;  that  is,  to  exprefs  the  activity  or  motion  of  the  fpirit 
of  animation,  at  the  time  it  produces  the  contractions  of  the 
fibrous  parts  of  the  fyftem.  It  may  be  fuppofed  that  there  may 
exift  a  greater  or  lefs  mobility  of  the  fibrous  parts  of  our  fyftem, 
or  a  propenfity  to  be  ftimulated  into  contraction  by  the  greater 
or  lefs  quantity  or  energy  of  the  fpirit  of  animation  ;  and  that 
hence  if  the  exertion  of  the  fenforial  power  be  in  its  natural 
(late,  and  the  mobility  of  the  fibres  be  increafed,  the  fame  quan- 
tity of  fibrous  contraction  will  be  caufed  as  if  the  mobility  of 
the  fibres  continues  in  its  natural  ftate,  and  the  fenforial  exertion 
be  increafed. 

Thus  it  may  be  conceived,  that  in  difeafes  accompanied  with 
ftrength,  as  in  inflammatory  fevers  with  arterial  ftrength,  that 
the  caufe  of  greater  fibrous  contraction  may  exift  in  the  increaf- 
ed mobility  of  the  fibres,  whofe  contractions  are  thence  both 
more  forcible  and  more  frequent.  And  that  in  difeafes  attended 
with  debility,  as  in  nervous  fevers,  where  the  fibrous  contrac- 
tions are  weaker,  and  more  frequent,  it  may  be  conceived  that 
the  caufe  confifts  in  a  decreafe  of  mobility  of  the  fibres  ;  and 
that  thofe  weak  conftitutions,  which  are  attended  with  cold 
extremities  and  large  pupils  of  the  eyes,  may  poffefs  lefs  mobil- 
ity of  the  contractile  fibres,  as  well  as  lefs  quantity  of  exertion 
of  the  fpirit  of  animation. 

In  ant  wer  to  this  mode  of  reafoning  it  may  be  fufficient  to  ob- 
ferve,  that  the  contractile  fibres  confift  of  inert  matter,  and 
when  the  fenforial  power  is  withdrawn,  as  in  death,  they  poffefs 
no  power  of  motion  at  all,  but  remain  in  their  laft  ftate,  whether 
of  contraction  or  relaxation,  and  rrmft  thence  derive  the  whole 

of 


SECT.  XII.  i.  7.        AND  EXERTION.  5 1 

of  this  property  from  the  fpirit  of  animation.  At  the  fame  time 
it  is  not  improbable,  that  the  moving  fibres  of  ftrong  people  may 
poflefs  a  capability  of  receiving  or  containing  a  greater  quantity 
of  the  ipirit  of  animation  than  thofe  of  weak  people. 

In  every  contra&ion  of  a  fibre  there  is  an  expenditure  of  the 
fenforial  power,  or  fpirit  of  animation  ;  and  where  the  exertion 
of  this  fenforial  power  has  been  for  fome  time  increafed,  and  the 
mufcles  or  organs  of  fenfe  have  in  confequence  afted  with 
greater  energy,  its  propenfity  to  a£Hvity  is  proportionally  leflen- 
ed  ;  which  is  to  be  afcribed  to  the  exhnuflion  or  diminution  of 
its  quantity.  On  the  contrary,  where  there  has  been  lefs  fibrous 
contra&ion  than  ufual  for  a  certnin  time,  the  fenforial  power  or 
fpirit  of  animation  becomes  accumulated  in  the  ina£live  part  of 
the  fyftem.  Hence  vigour  fucceeds  reft,  and  hence  the  propen- 
fity to  a&icn  of  all  our  organs  of  fenfe  and  mufcles  is  in  a  (late 
of  perpetual  flu&uation.  The  irritability  for  inftance  of  the 
retina,  that  is,  its  quantity  of  fenforial  power,  varies  every  mo- 
ment according  to  the  brightnefs  or  obfcurity  of  the  object  laft 
beheld  compared  with  the  prefent  one.  The  fame  occurs  to 
our  fenfe  of  heat,  and  to  every  part  of  our  fyliern,  which  is  ca- 
pable of  being  excited  into  adlion. 

When  this  variation  of  the  exertion  of  the  fenforial  power  be- 
comes much  and  permanently  above  or  beneath  the  natural 
quantity,  it  becomes  a  difeafe.  If  the  irritative  motions  be  too 
great  or  too  little,  it  fhews  that  the  ftimulus  of  external  things 
affe&s  this  fenforial  power  too  violently  or  too  inertly.  If  the 
fenfitive  motions  be  too  great  or  too  little,  the  caufe  arifes  from 
the  deficient  or  exuberant  quantity  of  fenfation  produced  in 
confequence  of  the  motions  of  the  mufcular  fibres  or  organs  of 
fenfe ;  if  the  voluntary  adlions  are  difeafed  the  caufe  is  to  be 
looked  for  in  the  quantity  of  volition  produced  in  confequence 
of  the  defire  or  averfion  occafioned  by  the  painful  or  pleafurable 
fenfations  above  mentioned.  And  the  difeafes  of  aflbciation 
probably  depend  on  the  greater  or  lefs  quantify  of  the  other 
three  fenforial  powers  by  which  they  were  formed. 

From  whence  it  appears  that  the  propenfity  to  action,  wheth- 
er it  be  called  irritability,  fenfibility,  voluntarity,  or  afTociability, 
is  only  another  mode  of  expreflion  for  the  quantity  of  fenforial 
power  refiding  in  the  organ  to  be  excited.  And  that  on  the 
contrary  the  words  Jnirritability  and  infenfibility,  together  with 
inaptitude  to  voluntary  and  afibciate  motions,  are  fynonymous 
with  deficiency  of  the  quantity  of  fenforial  power,  or  of  the 
fpirit  of  animation,  refiding  in  the  organs  to  rje  excited. 

II.  Of 


52  OF  STIMULUS         SECT.  XIL  2.  i. 

II.   Of  fenforial  Exertion^ 

i.  There  are  three  circumftances  to  be  attended  to  hi  the 
production  of  animal  motions,  id.  The  flimulus.  ad.  The 
fenforial  power.  3d.  The  contractile  fibre,  ift.  A  ftimulus, 
external  to  the  organ,  originally  induces  into  action  the  fenfo- 
rial faculty  termed  irritation  ;  this  produces  the  contraction  of 
the  fibres,  which,  if  it  be  perceived  at  all,  introduces  pleafure  or 
pain  ;  which  in  their  active  (tare  are  termed  fenfation  ;  which 
is  another  fenforial  faculty,  and  occafionally  produces  contrac- 
tion of  the  fibres  ;  this  pleafure  or  pain  is  therefore  to  be  con- 
fidered  as  another  ftimulus,  which  may  either  act  alone  or  in 
conjun&ion  with  the  former  faculty  of  the  fenforium  termed 
irritation.  This  new  ftimulus,  of  pleafure  or  pain  either  induces 
into  action  the  fenforial  faculty  termed  fenfation,  which  then 
produces  the  contraction  of  the  fibres  ;  or  it  introduces  defire 
or  averfion,  which  excite  into  action  another  fenforial  faculty, 
termed  volition,  and  may  therefore  be  confidered  as  another 
ftimulus,  which  either  alone  or  in  conjunction  with  one  or  both 
of  the  two  former  faculties  of  the  fenforium  produces  the  con- 
traction of  animal  fibres.  There  is  another  fenforial  power, 
that  of  a  aflbciation,  which  perpetually,  in  conjunction  with  one 
or  more  of  the  above,  and  frequently  fingly,  produces  the  con- 
traction of  animal  fibres,  and  which  is  itfelf  excited  into  action 
by  the  previous  motions  of  contracting  fibres. 

Now  as  the  fenforial  power,  termed  irritation,  refiding  in  any 
particular  fibres,  is  excited  into  exertion  by  the  (timulus  of  ex- 
ternal bodies  a£ting  on  thofe  fibres  ;  the  fenforial  power,  termed 
fenfation,  refiding  in  any  particular  fibres  is  excited  into  exertion 
by  the  ftimulus  of  pleafure  or  pain  a6ting  on  thofe  fibres  ;  the 
fenforial  power,  termed  volition,  refiding  in  any  particular  fibres 
is  excited  into  exertion  by  the  ftimulus  of  defire  or  averfion  ; 
and  the  fenforial  power,  termed  aflbciation,  refiding  in  any  par^ 
tidar  fibres,  is  excited  into  adtion  by  the  ftimulus  of  other  fi- 
brous motions,  which  had  frequently  preceded  them.  The 
word  ftimulus  may  therefore  be  ufed  without  impropriety  of 
language,  for  any  of  thefe  four  caufes,  which  excite  the  four 
fenforial  powers  into  exertion.  For  though  the  immediate 
caufe  of  volition  has  generally  been  termed  a  motive  ;  and  that 
of  irritation  only  has  generally  obtained  the  name  of  Jlimulus  ; 
yet,  as  the  immediate  caufe,  which  excites  the  fenforial  powers 
of  fenfation,  or  of  aifociation,  into  exertion,  have  obtained  no 
general  name,  we  (hall  ufe  the  word  ftimulus  for  them  all. 

Hence  the  quantity  of  motion  produced  in  any  particular 
part  of  the  animal  iyftem  will  be  as  the  quantity  of  ftimulus, 

a,nd 


SEGT.  XII.  2.  i.         AND  EXERTION.  53 

and  the  quantity  of  fenforial  power,  or  fpirit  of  animation,  re- 
dding in  the  contracting  fibres.  Where  both  thefe  quantities 
are  great  Jlrength  is  produced,  when  that  word  is  applied  to  the 
motions  of  animal  bodies.  Where  either  of  them  is  deficient, 
lueahiefs  is  procured,  as  applied  to  the  motions  of  animal  bodies. 

Now  as  the  ienforial  power,  or  fpirit  of  animation,  is  perpet- 
ually exhaufted  by  the  expenditure  of  it  in  fibrous  contractions, 
and  is  perpetually  renewed  by  the  fecretion  or  production  of  it 
in  the  brain  and  fpinal  marrow,  the  quantity  of  animal  ftrength 
muft  be  in  a  perpetual  date  of  fluctuation  on  this  account ;  and 
if  to  this  be  added  rhe  unceafing  variarion  of  all  the  four  kinds 
of  ftimuius  above  defcribed,  which  produce  the  exertions  of  the 
fenforial  powers,  the  ceafelefs  viciflitude  of  animal  ftrength  be- 
comes eafiiy  comprehended. 

If  the  quantity  of  fenforial  power  remains  the  fame,  and  the 
quantity  of  ftimuius  be  lefiened,  a  weaknefs  of  the  fibrous  con- 
traction1 ersfues,  which  may  be  denominated  debility  from  defeEl 
efjiirnuius.  If  the  quantity  of  ftimuius  remains  the  fame,  and 
the  quantity  of  fenforial  power  be  leifened,  another  kind  of 
M  viicfs  eirues,  u  hich  may  be  termed  debility  from  defect  offen- 
povi-er  ;  the  former  of  thefe  is  called  by  Dr.  Brown,  in 
i.  ,  Elements  of  Medicine,  direct  debility,  and  the  latter  Indi- 
ra ;•  debili  y  The  coincidence  of  fome  parts  of  this  work  with 
correlpondent  deductions  in  the  Brunonian  Elementa  Medi- 
cinse  ;  a  work  (with  fome  exceptions)  of  great  genius,  muft  be 
confidered  as  confirmations  of  the  truth  of  the  theory,  as  they 
were  probably  arrived  at  by  different  trains  of  reafoning. 

Thus  in  thofe  who  have  been  expofed  to  cold  and  hunger 
there  is  a  deficiency  of  ftimuius.  While  in  nervous  fever  there 
is  a  deficiency  of  fenforial  power.  And  in  habitual  drunkards, 
in  a  morning  before  their  ulual  potation,  there  is  a  deficiency 
both  of  ftimuius  and  of  fenforial  power.  While,  on  the  other 
hand,  in  the  beginning  of  intoxication  there  is  an  excefs  of  •ftim- 
uius ;  in  the  hot-ach,  after  the  hands  have  been  immerfed  in 
fnow  there  is  a  redundancy  of  fenforial  power  ;  and  in  inflam- 
ma'ory  difeafes  with  arterial  ftrength,  there  is  an  excefs  of  both. 

Hence  if  the  ienforial  power  be  leffened,  while  the  quantity 
of  ftimuius  remains  the  fame,  as  in  nervous  fever,  the  frequen- 
cy of  repetition  of  the  arterial  contractions  may  continue,  but 
their  force  in  refpect  to  removing  obftacles,  as  in  promoting  the 
circulation  of  the  blood,  or  the  velocity  of  each  contraction, 
will  be  diminifhed,  that  is,  the  animal  ftrength  will  be  leflened. 
And  fecoridly,  if  the  quantity  of  fenforial  power  be  leiTened,  and 
the  ftimuius  be  increased  to  a  certain  degree,  as  in  giving  opium 

in 


$4  OF  STIMULUS         SECT.  XII.  2.  i. 

in  nervous  fevers,  the  arterial  contractions  may  be  performed 
more  frequently  than  natural,  yet  with  lefs  ftrength. 

And  thirdly,  if  the  fenforial  power  continues  the  fame  in  re- 
fpeft  to  quantity,  and  the  ftimulus  be  fomewhat  diminifhed,  as  in 
going  into  a  darkifti  room,  or  into  a  coldifn  bath,  fuppofe  of  a- 
bout  eighty  degrees  of  heat,  as  Buxton-bath,  a  temporary  weak- 
nefsof  the  affected  fibres  is  induced,  till  an  accumlation  of  ien- 
forial  power  gradually  fucceeds,  and  counterbalances  the  de- 
ficiency of  ftimulus,  and  then  the  bath  ceafes  to  feel  cold,  and 
the  room  ceafes  to  appears  dark  ;  becaufe  the  fibres  of  the  fub- 
cutaneous  veflels,  or  of  the  organs  of  fenfe,  aft  with  their  ufu- 
al  energy. 

A  fet  of  mufcular  fibres  may  thus  be  ftimulated  into  violent 
exertion,  that  is,  they  may  aft  frequently,  and  with  their  whole 
fenforial  power,  but  may  neverthelefs  not  acl:  ftrongly  ;  becaufe 
the  quantity  of  their  fenforial  power  was  originally  fmall,  or 
was  previoufly  exhaufted.  Hence  a  ftimulus  may  be  great,  and 
the  irritation  in  confequerice  aft  with  its  full  force,  as  in.  the  hot 
paroxyfms  of  nervous  fever  ;  but  if  the  fenforial  power,  termed 
irritation,  be  fmall  in  quantity,  the  force  of  the  fibrous  contrac- 
tions, and  the  times  of  their  continuance  in  their  contracted 
ftate,  will  be  proportionally  fmall. 

In  the  fame  manner  in  the  hot  paroxyfm  of  putrid  fevers, 
•which  are  fhewn  in  Seft.  XXXIII.  to  be  inflammatory  fevers 
with  arterial  debility,  the  fenforial  power  termed  fenfation  is  ex- 
erted with  great  aftivity,  yet  the  fibrous  contractions,  which 
produce  the  circulation  of  the  blood,  are  performed  without 
ftrength,  becaufe  the  quantity  of  fenforial  power  then  refiding 
in  that  part  of  the  fyftem  is  fmall. 

Thus  in  irritative  fever  with  arterial  ftrength,  that  is,  with 
excefs  of  fpirit  of  animation,  the  quantity  of  exertion  during 
the  hot  part  of  the  paroxyfm  is  to  be  eftimated  from  the  quan- 
tity of  itimulus,  and  the  quantity  of  fenforial  power,  while  in 
fenfitive  (or  inflammatory)  fever  with  arterial  ftrength,  that  is, 
with  excefs  of  fpirit  of  animation,  the  violent  and  forcible  ac- 
tions of  the  vafcular  fyftem  during  the  hot  part  of  the  paroxyfm 
are  induced  by  the  exertions  of  two  fenforial  powers,  which  are 
excited  by  two  kinds  of  ftimulus.  Thefe  are  the  fenforial  pow- 
er of  irritation  excited  by  the  ftimulus  of  bodies  external  to  the 
moving  fibres,  and  the  fenforial  power  of  fenfation  excited  by 
the  pain  in  confequence  of  the  increafed  contractions  of  thofe 
moving  fibres. 

And  in  infane  people  in  fome  cafes  the  force  of  their  mufcu- 
lar aft  ions  will  be  in  proportion  to  the  quantity  of  fenforial 
power,  which  they  poifefs,  and  the  quantity  of  the  ftimulus  of 

defire 


SECT.  XII.  2.  2.         AND  EXERTION.  55 

defire  or  averfion,  which  excites  their  volition  into  action.  At 
the  fame  time  in  other  cafes  the  ftimulus  of  pain  or  pleafure, 
and  the  ftimulus  or  external  bodies,  may  excite  into  aclion  the 
fenforial  powers  of  ienfation  and  irritation,  and  thus  add  great- 
er force  to  their  mufcular  actions. 

2.  The  application  of  the  ftimulus,  whether  that  ftimulus  be 
fome  quality  of  external  bodies,  or  pleafure  or  pain,  or  defire  or 
averfion,  or  a  link  of  aflbciation,  excites  the  correfpondent  fenfo- 
rial power  into  action,  and  this  caufes  the  contraction  of  the  fi- 
bre. On  the  contraction  of  the  fibre  a  part  of  the  fpirit  of  ani- 
mation becomes  expended,  and  the  fibre  ceaies  to  contract, 
though  the  ftimulus  continues  to  be  applied  ;  till  in  a  certain 
time  the  fibre  having  received  a  fupply  of  fenforial  power  is 
ready  to  contract  again  if  the  ftimulus  continues  to  be  applied. 
If  the  ftimulus  on  the  contary  be  withdrawn,  the  fame  quanti- 
ty of  quiefcent  fenforial  power  becomes  refident  in  the  fibre  as 
before  its  contraction  ;  as  appears  from  the  readinefs  for  action 
of  the  large  locomotive  mufcles  of  the  body  in  a  ihort  time  af- 
ter common  exertion. 

But  in  thofe  mufcular  fibres,  which  are  fubject  to  conftant 
ftimulus,  as  the  arteries,  glands,  and  capillary  veflels,  anothet 
phenomenon  occurs,  if  their  accuftomed  ftimulus  be  withdrawn  ; 
which  is,  that  the  fenforial  power  becomes  accumlated  in  the: 
contractile  fibres,  owing  to  the  want  of  its  being  perpetually 
expended,  or  caried  away,  by  their  ufual  unremitted  contrac- 
tions. And  on  this  account  thofe  mufcular  fibres  become  af- 
terwards excitable  into  th^ir  natural  actions  by  a  much  weaker 
ftimulus  ;  or  into  unnatural  violence  of  action  by  their  accuf- 
tomed ftimulus,  as  is  feen  in  the  hot  fits  of  intermittent  fevers, 
which  are  in  confequence  of  the  previous  cold  ones.  Thus  the 
minute  veflels  of  the  fkin  are  conftantly  ftimulated  by  the 
fluid  matter  of  heat  ;  if  the  quantity  of  this  ftimulus  of  heat  be 
a  while  diminifhed,  as  in  covering  the  hands  with  fnow,  the 
veflels  ceafe  to  act,  at>  appears  from  the  palenefs  of  the  fkin  ;  if 
this  cold  application  of  fnow  be  continued  but  a  fhort  time,  the 
fenforial  power,  which  had  habitually  been  fupplied  to  the  fi- 
bres, becomes  now  accumulated  in  them,  owing  to  the  want  of 
its  being  expended  by  their  accuftomed  contractions.  And 
thence  a  lefs  ftimulus  of  heat  will  now  excite  them  into  violent 
contractions. 

If  the  quiefcence  of  fibres,  which  had  previouily  been  fubjecT: 
to  perpetual  ftimulus,  continues  a  longer  time  j  or  their  accuf- 
tomed ftimulus  be  more  completly  withdrawn  ;  the  accumula- 
tion of  fenlorial  power  becomes  ftill  greater,  as  in  thofe  expofed 
to  cold  and  hunger  ;  pain  is  produced,  and  the  organ  gradually 

dies 


56  OF  STIMULUS  SECT.  XII.  2.  g. 

dies  from  the  chemical  changes,  which  take  place  in  it  ;  or  it  is 
at  a  great  diftance  of  time  reftored  to  adtion  by  ftimulus  appli- 
ed with  great  caution  in  fmall  quantity,  as  happens  to  fome 
larger  animals  and  to  many  infects,  which  during  the  winter 
months  lie  benumbed  with  cold,  and  are  faid  to  fleep,  and  to 
perfons  apparently  drowned,  or  apparently  frozen  to  death. 
Snails  have  been  faid  to  revive  by  throwing  them  into  water  af- 
ter having  been  many  years  flmt  up  in  the  cabinets  of  the  curi- 
ous ;  and  eggs  and  feeds  in  general  are  reftored  to  life  after 
many  months  of  torpor  by  the  ftimulus  of  warmth  and  moifture. 

The  inflammation  of  ichirrous  tumours,  which  have  long 
exifted  in  a  ftate  of  inaction,  is  a  procefs  of  this  kind  ;  as  well 
as  the  fenfibility  acquired  by  inflamed  tendones  and  bones,  which 
had  at  their  formation  a  fimilar  fenfibility,  which  had  fo  long 
lain  dormant  in  their  uninflamed  ftate. 

3.  If  after  long  quiefcence  from  defect  of  ftimulus  the  fibres, 
which  had  prcvioufly  been  habituated  to  perpetual  ftimulus,  are 
again  expofed  to  but  their  ufual  quantity  of  ir ;  as  in  thofe  who 
have  fuffered  the  extremes  of  coid  or  hunger  ;  a  violent  exer- 
tion of  the  affected  organ  commences,  owing,  as  above  explain- 
ed, to  the  great  accumlation  of  fenforial  power,  This  violent 
exertion  not  only  diminiflves  the  accumulated  fpirit  of  anima- 
tion, but  at. the  fame  time  induces  pleafure  or  pain  into  the  fyf- 
tem, which,  whether  it  be  fucceeded  by  inflammation  or  not, 
becomes  an  additional  ftimulus,  and  acting  along  with  the  for- 
mer one,  produces  ftill  greater  exertions  -,  and  thus  reduces  the 
fenforial  power  in  the  contracting  fibres  beneath  its  natural 
quantity. 

When  the  fpirit  of  animation  thus  exhaufted  by  ufelefs  ex- 
ertions, the  organ  becomes  torpid  or  unexcitable  into  a6tion,  and 
"a  fecond  fit  of  quiefcence  fucceeds  that  of  abundant  activity. 
During  this  fecond  fit  of  quiefcence  the  fenforial  power  be- 
comes again  accumulated,  and  another  fit  of  exertion  follows  in 
train.  Thefe  viciffitudes  of  exertion  and  inenion  of  the  arterial 
fyftem  conftitute  the  paroxyfms  of  remittent  fevers  ;  or  inter- 
mittent ones,  when  there  is  an  interval  of  the  natural  action  of 
the  arteries  between  the  exacerbations. 

In  thefe  paroxyfms  of  fevers,  which  confift  of  the  libration  of 
the  arterial  fyftem  between  the  extremes  of  exertion  and  qui- 
efcence, either  the  fits  become  lefs  and  lefs  violent  from  the  con- 
tractile fibres  becoming  lefs  excitable  to  the  fti  riums  by  habit, 
that  is  by  becoming  accuftomed  to  it,  as  explained  below,  XII. 
2.  I.  or  the  whole  fenforial  power  becomes  exhaufted,  and  the 
arteries  ceafe  to  beat,  and  the  patient  dies  in  the  coid  part  of 
the  paroxyfm.  Or  fecondly,  fo  much  pain  is  introduced  int© 

the 


SECT.  XII.  2. 4.        AND  EXERTION.  57 

the  fyftem  by  the  violent  contractions  of  the  fibres,  that  inflam- 
mation arifes,  which  prevents  future  cold  fits  by  expending  a 
part  of  the  fenforial  power  in  the  extenfion  of  old  velfels  or  the 
production  of  new  ones ;  and  thus  preventing  the  too  great  ac- 
cumulation or  exertion  of  it  in  other  parts  of  the  fyftem  ;  or 
which  by  the  great  increafe  of  ftimulus  excites  into  great  action 
the  whole  glandular  fyttem  as  well  as  the  arterial,  and  thence  a 
greater  quantity  of  fenforial  power  is  produced  in  the  brain,  and 
thus  its  exhauftion  in  any  peculiar  part  of  the  fyftem  ceaies  to  be 
effected. 

4.  Or  thirdly,  in  confequence  of  the  painful  or  pleafurable 
fenfation  above  mentioned,  defire  and  averfion  are  introduced, 
and  inordinate  volition  fucceeds  ;  which  by  its  own  exertions 
expends  fo  much  of  the  fpirit  of  animation,  that  the  two  other 
fenforial  faculties,  or  irritation  and  fenfation,  aft  fo  much  more 
feebly  ;  that  the  paroxyfms  of  fever,  or  that  libration  between 
the  extremes  of  exertion  and  inactivity  of  the  arterial  fyftem, 
gradually  fubfides.  On  this  account  a  temporary  infanity  is  a 
favourable  fign  in  fevers,  as  I  have  had  fome  opportunities  of 
obferving. 

III.   Of  repeated  Stimulus. 

I.  When  a  ftimulus  is  repeated  more  frequently  than  the  ex- 
penditure of  fenforial  power  can  be  renewed  in  the  acling  or- 
gan, the  effect  of  the  ftimulus  becomes  gradually  diminifhed. 
Thus  if  two  grains  of  opium  be  fwallowed  by  a  perfon  unufed 
to  fo  ftrong  a  ftimulus,  all  the  vafcular  fydems  in  the  body  aft 
with  great  energy,  all  the  fecretions  and  the  abforption  from 
thofe  fecreted  fluids  are  increafed  in  quantity  ;  and  ple?»fure  or 
pain  are  introduced  into  the  fyftem,  which  adds  an  additional 
ilimulus  to  that  already  too  great.  After  fome  hours  the  fenfo- 
riai  power  becomes  diminiihed  in  quantity,  expended  by  the 
great  activity  of  the  fyftem  ,  and  thence,  when  the  ftimulus  of 
the  opium  is  withdrawn,  the  fibres  will  not  obey  their  ufua!  de- 
gree of  natural  ftimulus,  and  a  confequent  torpor  or  quiefcence 
fucceeds,  as  is  experienced  by  drunkards,  who  on  the  day  after 
a  great  excefs  of  fpirituous  potation,  feel  indigeftion,  head-ach, 
and  general  debility. 

In  this  fit  of  torpor  or  quiefcence  of  a  part  or  of  the  whole 
of  the  fyftem,  an  accumulation  of  the  fenforial  power  in  the  af- 
fe&ed  fibres  is  formed,  and  occafions  a  fecond  paroxyfm  of  ex- 
ertion, by  the  application  only  of  the  natural  ftimulus,  and  thus 
a  libration  of  the  fenforial  exertion  between  one  excefs  and  the 


other  continues  for  two  or  three  days,  where  the  ftimu'us 
VOL.  I,  I  >-  viok 


us  was 
Solent 


5 8  OF  STIMULUS  SECT.  XII.  3.5, 

violent  in  degree  ;  and  for  weeks  in  fome  fevers,  from  the  ftim- 
ulus  of  contagious  matter. 

But  if  a  fecond  dofe  of  opium  be  exhibited  before  the  fibres 
have  regained  their  natural  quantity  of  fenforial  power,  its  ef- 
fect will  be  much  lefs  than  the  former,  becaufe  the  fpirit  of  an- 
imation or  fenforial  power  is  in  part  exhaufted  by  the  previous 
excefs  of  exertion.  Hence  all  medicines  repeated  too  frequent- 
ly gradually  lofe  their  effecl:,  as  opium  and  wine.  Many  things 
of  difagreeable  tafte  at  firft  ceafe  to  be  difagreeable  by  frequent 
repetition,  as  tobacco  :  grief  and  pain  gradually  diminifli,  and 
at  length  ceafe  altogether  j  and  hence  life  itfelf  becomes  toler- 
able. 

Befides  the  temporary  diminution  of  the  fpirit  of  animation 
or  fenforial  power,  which  is  naturally  ftationary  or  refident  in 
every  living  fibre,  by  a  fingle  exhibition  of  a  powerful  ftimulus, 
the  contractile  fibres  themfelves,  by  the  perpetual  application  of 
a  new  quantity  of  ftimulus,  before  they  have  regained  their  nat- 
ural quantity  of  fenforial  power,  appear  to  fuffer  in  their  capa- 
bility of  receiving  fo  much  as  the  natural  quantity  of  fenforial 
power  i  and  hence  a  permanent  deficiency  of  fpirit  of  anima- 
tion takes  place,  however  long  the  ftimulus  may  have  been 
withdrawn.  On  this  cafe  depends  the  permanent  debility  of 
thofe,  who  have  been  addicled  to  intoxication,  the  general  weak- 
nefs  of  old  age,  and  the  natural  debility  or  inirritability  of  thofe, 
who  have  pale  (kins  and  large  pupils  of  their  eyes. 

There  is  a  curious  phenomenon  belongs  to  this  place,  which 
has  always  appeared  difficult  of  folution  ;  and  that  is,  that  opi- 
um or  aloes  may  be  exhibited  in  fmall  dofes  at  firft,  and  gradu- 
ally increafed  to  very  large  ones  without  producing  a  ftupor  or 
diarrhoea.  In  this  cafe,  though  the  opium  and  aloes  are  given 
in  fuch  fmall  dofes  as  not  to  produce  intoxication  or  catharfis, 
yet  they  are  exhibited  in  quantities  fufficient  in  fome  degree  to 
exhaufl  the  fenforial  power,  and  hence  a  ftronger  and  a  ftrong- 
er  dofe  is  required  ;  otherwife  the  medicine  would  foon  ceafe 
to  acl  at  all. 

On  the  contrary  if  the  opium  or  aloes  be  exhibited  in  a  large 
dofe  at  firft,  fo  as  to  produce  intoxication  or  diarrhoea  ;  after  a 
few  repetitions  the  quantity  of  either  of  them  may  be  diminifh- 
ed,  and  they  will  ftill  produce  this  effect.  For  the  more  pow- 
erful ftimulus  diflevers  the  progrefllve  catenations  of  animal  mo- 
tions, defcribed  in  Seel.  XVII.  and  introduces  a  new  link  be- 
tween them  -,  whence  every  repetition  ftrengthens  this  new  af- 
fociation  or  catenation,  and  the  ftimulus  may  be  gradually  de- 
creafed,  or  be  nearly  withdrawn,  and  yet  the  effect  (hall  con- 
tinue ;  becaufe  the  fenforial  power  of  aflbciation  or  catenation 

being 


SECT.  XII.  3.  2.         AND  EXERTION.     K  59 

being  united  with  the  ftimulus,  increafes  in  energy  with  every 
repetition  of  the  catenated  circle  ;  and  it  is  by  thefe  means  that 
all  the  irritative  affociations  of  motions  are  originally  produced. 

Thus  if  the  Peruvian  bark  be  given  in  the  intervals  between 
the  fits  of  intermittent  fever  in  fuch  fmall  dofes,  as  not  to  pre- 
vent the  returns  of  fever,  the  conftitution  ceafes  to  obey  its 
ftimulus,  and  the  difeafe  cannot  be  cured  even  by  the  largeft 
dofes  of  bark,  unlefs  the  patient  ceafes  to  lake  any  for  a  few 
days  previous  to  the  exhibition  of  larger  dofes.  But  if  large 
dofes  be  at  firft  exhibited  fo  as  to  prevent  the  return  of  fever, 
fmall  ones  taken  afterwards  will  continue  to  prevent  the  return 
of  it. 

2.  When  a  ftimulus  is  repeated  at  fuch  diftant  intervals  of 
time,  that  the  natural  quantity  of  fenforial  power  becomes  com- 
pletely reftored  in  the  afting  fibres,  it  will  act  with  the  fame  en- 
ergy as  when  firft  applied.     Hence  thofe  who  have  lately  accuf- 
tomed  themfelves  to  large  dofes  of  opium   by  beginning  with 
fmall  ones,  and  gradually  increafing  them,  and  repeating  them 
frequently  as  mentioned  in  the  preceding  paragraphs ;  if  they 
intermit  the  ufe  of  it  for  a  few  days  only,  muft  begin  again  with 
as  fmall  dofes  as  they  took  at  firft,  otherwife,  they  will  experi- 
ence the  inconveniences  of  intoxication. 

On  this  circumftance  depend  the  conftant  unfailing  effects  of 
the  various  kinds  of  ftimulus,  which  excite  into  a&ion  all  the 
vafcular  fyftems  in  the  body  ;  the  arterial,  venous,  abforbent, 
and  glandular  veffels,  are  brought  into  perpetual  unwearied  ac- 
tion by  the  fluids,  which  are  adapted  to  itimuhte  them  ;  but 
thefe  have  the  fenforial  power  of  aifociation  added  to  that  of  ir- 
ritation, and  even  in  fome  degree  that  of  feftfation,  and  even  of 
volition,  as  will  be  fpoken  of  in  their  places ;  and  life  itfeif  is  thus 
carried  on  by  the  production  of  fenforial  power  being  equal  to  its 
wafte  or  expenditure  in  the  perpetual  movement  of  the  vafcu- 
lar organization. 

3.  When  a  ftimulus  is  repeated  at  uniform  intervals  of  time 
with  fuch  diftances  between  them,  that  the  expenditure  of  fen- 
forial power  in  the  acting  fibres  becomes  completely  renewed, 
the  effect  is  produced  with  greater  facility  or  energy      For  the 
fenforial  power  of  affociation  is  combined   with  the  fenforial 
power  of  irritation,  or,  in  common  language,  the  acquired  hab- 
it affifts  the  power  of  the  ftimulus. 

This  circumftance  not  only  obtains  in  the  annual  and  diur- 
nal catenations  of  animal  motions  explained  in  Sect.  XXXVI. 
but  in  every  lefs  circle  of  actions  or  ideas,  as  in  the  burthen  of 
a  fong,  or  the  iterations  of  a  dance  ;  and  conftitutes  the  pleaf- 

ure 


(Jo  OF  STIMULUS  SECT.  XII.  3.4, 

ure  we  receive  from  repetition  and  imitation  ;  as  treated  of  in 
Sea  XXII.  2, 

4  When  a  ftimuhis  has  been  many  times  repeated  at  uni- 
for  >>  intervals,  ib  as  to  produce  the  complete  action  of  the  or- 
gan, it  may  then  be  gradually  dimimftied,  or  totally  withdrawn, 
and  the  action  of  the  organ  will  continue.  For  the  fenforial 
power  of  aflbciation  becomes  united  with  that  of  irritation,  and 
by  frequent  repetition  becomes  at  length  of  fufficienr  energy  to 
carry  on  the  new  link  in  the  circle  of  a&ions,  without  the  irri- 
tation which  at  firft  introduced  it. 

Hence,  when  the  bark  is  given  at  dated  intervals  for  the 
cure  of  intermittent  fevers,  if  fixty  grains  of  it  be  given  every 
three  hours  for  the  twenty- four  hours  preceding  the  expected 
paroxyfm,  fo  as  to  ftimulate  the  defective  part  of  the  fyftem  in- 
to action,  and  by  that  means  to  prevent  the  torpor  or  quiefcence 
of  the  fibres,  which  conftitutes  the  cold  fit ;  much  lefs  than  half 
the  quantity,  given  before  the  time  at  which  another  paroxyfm 
of  quiefcence  would  have  taken  place,  will  be  fufficient  to  pre- 
vent it  •,  becaufe  now  the  fenforial  power,  termed  afTociation, 
acts  in  a  twofold  manner.  Firil,  in  refpect  to  the  period  of 
the  catenation  in  which  the  cold  fit  was  produced,  which  is  now 
diiTevered  by  the  ftronger  ftimulus  of  the  firft  doles  of  the  bark  ; 
and,  fecondiy>  becaufe  each  dofe  of  bark  being  repeated  at  peri- 
odical times,  has  its  eff:ct  mcreafed  by  the  fenforial  faculty  of 
afTociation  being  combined  with  that  of  irritation. 

Now,  when  fixty  grains  of  Peruvian  bark  are  taken  twice  a 
day,  fuppofe  at  ten  o'clock  and  at  fix,  for  a  fortnight,  the  irrita- 
tion excited  by  this  additional  ftimulus  becomes  a  part  of  the 
diurnal  circle  of  a£K£ms,  and  will  at  length  carry  on  the  increaf- 
ed  action  of  the  fyftem  without  the  afiiftance  of  the  ftimulus  of 
the  bark.  On  this  theory  the  bitter  medicines,  chalybeates, 
and  opiates  in  appropriated  dofes,  exhibited  for  a  fortnight,  give 
permanent  ftrength  to  pale  feeble  children,  and  other  weak 
conftitutions. 

5.  When  a  defect  of  ftimulus,  as  of  heat,  recurs  at  certain 
diurnal  intervals,  which  induces  fome  torpor  or  quiefcence  of 
a  part  of  the  fyftem,  the  diurnal  catenation  of  actions  becomes 
difordered,  and  a  new  aflbciation  with  this  link  of  torpid  action 
is  formed  •,  on  the  next  period  the  quantity  of  quiefcence  will  be 
increafed,  fuppofe  the  fame  defect  of  ftimulus  to  recur,  becaufe 
now  the  new  ailbciation  confpires  with  the  defective  irritation 
in  introducing  the  torpid  action  of  this  part  of  the  diurnal  cat- 
enation. In  this  manner  many  fever-fits  commence,  where  the 
patient  is  for  fome  days  indifpofed  at  certain  hours,  before  the 

cold 


SECT.  XII.  3. 6.         AND  EXERTION.  61 

cold  paroxyfm  of  fever  is  completely  formed.  See  Sect.  XVII. 
3.  3.  on  Catenation  of  Animal  Motions. 

6  If  a  ftimulus,  which  at  firft  excited  rhe  affected  organ  into 
fo  great  exertion  as  to  produce  fenfation,  be  continued  for  a 
certain  time,  it  will  ceafe  to  produce  fenfation  both  then  and 
when  repeated,  though  the  irritative  motions  in  confequence  of 
it  may  continue  to  be  re-excited. 

Many  catenations  of  irritative  motions  were  at  firft  fucceed- 
ed  by  fenfarion,  as  the  apparent  motions  of  objects  when  we 
walk  paft  them,  and  probably  the  vital  motions  themfelves  in 
the  early  ftate  of  our  exiftence.  But  as  thofe  fenfations  were 
followed  by  no  movements  of  the  fyftem  in  confequence  of 
them,  they  gradually  ceaied  to  be  produced,  not  being  joined  to 
anv  fucceeding  link  of  catenation.  Hence  contagious  matter, 
which  has  for  fome  weeks  ftimulated  the  fyftem  into  great  and 
permanent  fenfation,  ceafes  afterwards  to  produce  general  fenfa- 
tion, or  inflammation,  though  it  may  (till  induce  topical  irrita- 
tions. See  Sed  XXXIII.  2.  8.  XIX  10. 

Our  abforbent  fyftem  then  feems  to  receive  thofe  contagious 
matters,  which  it  has  before  experienced,  in  the  fame  manner  as 
it  imbibes  common  moifture  or  other  fluids  ;  that  is,  without 
being  thrown  into  fo  violent  action  as  to  produce  fenfation  ;  the 
confequence  of  which  is  an  increafe  of  daily  energy  or  activity, 
till  inflammation  and  its  confequences  fucceed. 

7.  If  a  ftimulus  excites  an  organ  into  fuch  violent  contrac- 
tions as  to  produce  fenfation,  the  motions  of  which  organ  had 
not  ufually  produced  fenfation,  this  new  fenforial  power,  added 
to  the  irritation  occafioned  by  the  ftimulus,  increafes  the  activ- 
ity of  the  organ.  And  if  this  activity  be  catenated  with  the  di- 
urnal circle  of  actions,  an  increafing  inflammation  is  produced  ; 
as  in  the  evening  paroxyfms  of  fmall-pox,  and  other  fevers  with 
inflammation.  And  hence  fchirrous  tumours,  tendons  and 
membranes,  and  probably  the  arteries  themfelves  become  in- 
flamed, when  they  are  ftrongly  ftimulated. 

IV.   Of  Stimulus  greater  than  natural. 

i.  A  quantity  of  ftimulus  greater  than  natural,  producing  an 
increafcd  exertion  of  fenforial  power,  whether  that  exertion  be 
in  the  mode  of  irritation,  fenfation,  volition,  or  aflbciation,  dimin- 
ifhes  the  general  quantity  of  it.  This  fact  is  obfervable  in  the 
progrefs  of  intoxication,  as  the  increafed  quantity  or  energy  of 
the  irritative  motions,  owing  to  the  ftimulus  of  vinous  fpirit,  in- 
troduces much  pleafurable  fenfation  into  the  fyftem,  and  much 
exertion  of  muicular  or  fenfual  motions  in  confequence  of  this 

increafed 


$2  OF  STIMULUS         SECT.  331. 4. 2. 

increafed  fenfation  ;  the  voluntary  motions,  and  even  the  aflbci- 
ate  ones,  become  much  impaired  or  diminifhed  ;  and  delirium 
and  daggering  fucceed.  See  Sect.  XXI.  on  Drunkennefs. 
And  hence  the  great  proftration  of  the  ftrength  of  the  locomo- 
tive mufcles  in  fome  fevers  is  owing  to  the  exhauftion  of  fenfo- 
rial power  by  the  increafed  action  of  the  arterial  fyftem. 

In  like  manner  a  ftirnulus  greater  than  natural,  applied  to  a 
part  of  the  fyftem,  increafes  the  exertion  of  fenforial  power  in 
that  part  and  diminifhes  it  in  fome  other  part.  As  in  the  com- 
mencement of  fcarlet  fever,  it  is  nfual  to  fee  great  rednefs  and 
heat  on  the  faces  and  breads  of  children,  while  at  the  fame  time 
their  feet  are  colder  than  natural ;  partial  heats  are  obfervable 
in  other  levers  with  debility,  and  are  generally  attended  with 
torpor  or  quiefcence  of  fome  other  part  of  the  fyftem.  But 
thefe  partial  exertions  of  fenforial  power  are  fometimes  attend- 
ed with  increafed  partial  exertions  in  other  parts  of  the  fyftem, 
which  fympathize  with  them,  as  the  flufhingof  the  face  after  a 
full  meal.  Both  thefe  therefore  are  to  be  afcribed  to  fym pathet- 
ic afibciations,  explained  in  Sect.  XXXV.  and  not  to  general 
exhauftion  or  accumulation  of  fenforial  power. 

2.  A  quantity  of  ftimulus  greater  than  natural,  producing  an 
increafed  exertion  of  fenforial  power  in  any  particular  organ, 
diminifhes  the  quantity  of  it  in  that  organ.     This  appears  from 
the  contractions  of  animal  fibres  being  not  fo  eafily  excited  by  a 
lefs  ftimulus  after  the  organ  has  been  fubjecled  to  a  greater. 
Thus  after  looking  at  any  luminous  object  of  a  fmall  fize,  as  at 
the  fetting  fun,  for  a  (liort  time,  fo  as  not  much  to  fatigue  the 
eye,  this  part  of  the  retina  becomes  lefs  fenfible  to  fmaller  quan- 
tities of-light ;  hence  when  the  eyes  are  turned  on  other  lefs  lu- 
minous parts  of  the  Iky,  a  dark  fpot  is  feen  refembling  the  fhape 
of  the  fun,  or  other  luminous  object  which  we  laft  behold.    See 
Seft.  XL.  No.  2. 

Thus  we  are  fome  time  before  we  can  diftinguifli  objects  in 
an  obfcure  room  after  coming  from  bright  day-light,  though  the 
iris  prefently  contracts  itfelf.  We  are  not  able  to  hear  weak 
founds  after  loud  ones.  And  the  ftomachs  of  thofe  who  have 
been  much  habituated  to  the  ftronger  ftimulus  of  fermented  or 
fpirituous  liquors  are  not  excited  into  due  aftion  by  weaker  ones. 

3.  A  quantity  of  ftimulus  fomething  greater  than  the  laft 
mentioned,  or  longer  continued,   induces  the  organ  into  fpaf- 
modic  a&ion,  which    ceafes  and  recurs  alternately      Thus  on 
looking  for  a  time  on  the  fetting  fun,  fo  as  not  greatly  to  fatigue 
the  fight,  a  yellow  (pectrum  is  feen  when  the  eyes  are  clofed 
and  covered,  which  continues  for  a  time,  and  then  difappears 
and  recurs  repeatedly  before  it  entirely  vaniflies.    See  Sect.  XL. 

No. 


SECT.  XII.  4. 4.  AND  EXERTION.  63 

No.  c.  Thus  the  action  of  vomiting  ceafes  and  is  renewed  by 
intervals,  although  the  emetic  drug  is  thrown  up  with  the  firft 
effort.  A  tenefmus  continues  by  intervals  fome  time  after  the 
exclufion  of  acrid  excrement ;  and  the  pulfations  of  the  heart  of 
a  viper  are  faid  to  continue  fome  time  after  it  is  cleared  from 
its  blood. 

In  thefe  cafes  the  violent  contractions  of  the  fibves  produce 
pain  according  to  law  4  •,  and  this  pain  conftitutes  an  additional 
kind  or  quantity  of  excitement,  which  again  induces  the  fibres 
into  contraction,  and  which  painful  excitement  is  again  renew- 
ed, and  again  induces  contractions  of  the  fibres  with  gradually 
diminifhing  effect. 

4.  A  quantity  of  flimulus  greater  than  that  laft  mentioned,  or 
longer  continued,  induces  the  antagonift  mufcles  into  fpafmodic 
action.     This  is  beautifully  illuftrated  by  the  ocular  fpedtra  de- 
fcribed  in  Sect.  XL.  No.  6.  to  which  the  reader  is  referred. 
From  thofe  experiments  there  is  reafon  to  conclude  that  the  fa- 
tigued part  of  the  retina  throws  itfelf  into  a  contrary  mode  of 
action  like  ofcitation  or  pandiculation,   as  foon  as  the  ftimulus, 
which  has  fatigued  it,  is  withdrawn  •,  but  that  it  ftill  remains  li- 
able to  be  excited  into  action  by  any  other  colours  except  the 
colour  with  which  it  has  been  fatigued.     Thus  the  yawning  and 
ftretching  the  limbs  after  a  continued  action  or  attitude  feems 
occafioned  by  the  antagonift  mufcles  being  ftimulated  by  their 
exteniion  during  the  contractions  of  thofe  in  action  or  in  the 
fituation  in  which  that  action  laft  left  them. 

5.  A  quantity  of  ftirnulus  greater  than  the  laft,  or  longer  con- 
tinued, induces  variety  of  convulfions  or  fixed  fpafms  either  of 
the  affected  organ  or  of  the  moving  fibres  in  the  other  parts  of 
the  body.     In  refpect  to  the  fpectra  in  the  eye  this  is  well  il- 
luftrated in  No.  7  and  8,  of  Sect  XL.     Epileptic  convulfions,  as 
the  emprofthotonos  and  opifthotonos,  with  a  cramp  of  the  calf 
of  the  leg,  locked  jaw,  and  other  cataleptic  fits,  appear  to  origi- 
nate from  pain,  as  fome  of  thefe  patients  fcream  aloud  before 
the  convulfion  takes  place ,  which  ieems  at  firft  to  be  an  effort 
to  relieve  painful  fenfation,  and  afterwards  an  effort  to  prevent  it. 

In  thefe  cafes  die  violent  contractions  of  the  fibres  produce  fo 
much  pain,  as  to  conftitute  a  perpetual  excitement  5  and  that  in 
fo  great  a  degree  as  to  allow  but  fmall  intervals  of  relaxation  of 
the  contracting  fibres  as  in  convulfions,  or  no  intervals  at  all  as 
in  fixed  fpafms. 

6  A  quantity  of  ftimulus  greater  than  the  laft,  or  longer  con- 
tinued, produces  a  paralyfis  of  the  organ.  In  many  cafes  this 
paralyfis  is  only  a  temporary  effect,  as  on  looking  long  on  a  fmall 
area  of  bright  red  filk  placed  on  a  fheet  of  white  paper  on  the 

floor 


*H  OF  STIMULUS         SECT.  XII.  5.  i, 

floor  in  a  ftrong  light,  the  red  filk  gradually  becomes  paler,  and 
at  length  difappears ;  which  evinces  that  a  part  of  the  retina,  by 
being  violently  excited,  becomes  for  a  time  unaffected  by  ;he 
ftimulus  of  that  colour.  Thus  cathartic  medicines,  opiates,  poi- 
fons,  contagious  matter,  ceafe  to  influence  our  fyftem  af;trr  it  has 
been  habituated  to  the  ufe  of  them,  except  by  the  exhibition  of 
increafed  quantities  of  them  ;  our  fibres  not  only  become  unaf- 
fecled  by  ftimuli,  by  which  they  have  previoufly  been  violently 
irritated,  as  by  the  matter  of  the  fmall-pox  or  meafles ;  bur  they 
alfo  become  unaffected  by  fenfation,  where  the  violent  exertions, 
which  difabled  them,  were  in  confequence  of  too  great  quantity 
of  fenfation.  And  lailly,  the  fibres  which  become  diiobedient 
to  volition,  are  probably  difabled  by  their  too  violent  exertions 
in  confequence  of  too  great  a  quantity  of  volition. 

After  every  exertion  of  our  fibres  a  temporary  paralyfis  fuc- 
ceecis,  whence  the  intervals  of  all  mufcular  contractions,  as  men- 
tioned in  No.  3  and  4  of  this  Section  ;  the  immediate  caufe  of 
thefe  more  permanent  kinds  of  paralyfis  is  probably  owing  in  the 
lame  manner  to  the  too  great  exhaullion  of  the  fpirit  of  anima- 
tion in  the  affected  part  j  fo  that  a  ftronger  ftimulus  is  required, 
or  one  of  a  different  kind  from  that,  which  occafioned  thofe  too 
violent  contractions,  to  again  excite  the  affected  organ  into  ac- 
tivity ;  and  if  a  ftronger  ftimulus  could  be  applied,  it  muft 
again  induce  paralyfis. 

For  thefe  powerful  ftimuli  excite  pain  at  the  fame  time,  that 
they  produce  irritation  -9  and  this  pain  not  only  excites  fibrous 
motions  by  its  ftimulus,  but  it  alfo  produces  volition  j  and  thus 
all  thefe  ftimuli  acting  at  the  fame  time,  and  fometimes  with 
the  addition  of  their  affociations,  produce  fo  great  exertion  as  to 
expend  the  whole  of  the  fenforial  power  in  the  affected  fibres. 

V.  Of  Stimulus  lefs  than  natural. 

I.  A  quantity  of  ftimulus  lefs  than  natural,  producing  a  de- 
ereafed  exertion  of  fenforial  power,  occafions  an  accumulation 
of  the  general  quantity  of  it.  This  circumftance  is  obfervable 
in  the  haemiplegia,  in  which  the  patients  are  perpetually  mov- 
ing the  mufcles,  which  are  unaffected.  On  this  account  we 
awake  with  greater  vigour  after  ileep,  becaufe  during  fo  many 
hours,  the  great  ufual  expenditure  of  fenforial  power  in  the  per- 
formance of  voluntary  adions,  and  in  the  exertions  of  our  or- 
gans of  fenie,  in  confequence  of  the  irritations  occafioned  by  ex- 
ternal objects  had  been  fufpended,  and  a  confequent  accumula- 
tion had  taken  place. 

In  like  manner  the  exertion  of  the  fenforial  power  lefs  than 

natural 


SECT.  XII.  5.  2.          AND  EXERTION.  65 

natural  in  one  part  of  the  fyftem,  is  liable  to  produce  an  increafe 
of  the  exertion  of  it  in  fome  other  part.  Thus  by  the  action  of 
vomiting,  in  which  the  natural  exertion  of  the  motions  of  the 
ftomach  are  deftroyed  or  diminifhed,  an  increafed  abforption  of 
the  pulmonary  and  cellular  lymphatics  is  produced,  as  is  known 
by  the  increafed  abforption  of  the  fluid  depofited  in  them  in 
dropfical  cafes.  But  thefe  partial  quiefcences  of  fenforial  power 
are  alfo  fometimes  attended  with  other  partial  quiefcences,  which 
fympathize  with  them,  as  cold  and  pale  extremities  from  hun- 
ger. Thefe  therefore  are  to  be  afcribed  to  the  afibciations  of 
fympathy  explained  in  Seel:.  XXXV.  and  not  to  the  general 
accumulation  of  fenforial  power. 

2.  A  quantity  of  ftimulus  lefs  than  natural,  applied  to  fibres 
previoufly  accuftomed  to  perpetual  ftimulus,  is  fucceetied  by  ac- 
cumulation of  fenforial  power  in  the  affected  organ.  The  truth 
of  this  propofition  is  evinced,  becaufe  a  ftimulus  lefs  than  nat- 
ural, if  it  be  fomewhat  greater  than  that  above  mentioned,  will 
excite  the  organ  fo  circumftanced  into  violent  activity.  Thus 
on  a  frofty  day  with  wind,  the  face  of  a  perfon  expofed  to  the 
wind  is  at  firft  pale  anc^  fhrunk  j  but  on  turning  the  face  from 
the  wind,  it  becomes  foon  of  a  glow  with  warmth  and  flushing. 
The  glpw  of  the  fkin  in  emerging  from  the  cold-bath  is  owing 
to  the  fame  cauie.  « 

It  does  not  appear,  that  an  accumulation  of  fenforial  power 
above  the  natural  quantity  is  acquired  by  thofe  mufcles,  which 
are  not  fubject  to  perpetual  ftimulus,  as  the  locomotive  mufcles  ; 
thefe,  after  the  greateft  fatigue,  oniy  acquire  by  reft  their  uiual 
aptitude  to  motion  ;  whereas  the  vafcular  fyftem,  as  the  heart 
and  arteries,  after  a  (horr  quiefcence  are  thrown  into  a  violent  ac- 
tion by  their  natural  quantity  of  ftimulus. 

Neverthelefs  by  this  accumulation  of  fenforial  power  during 
the  application  of  decreafed  ftimulus,  and  by  the  exhauftion  of 
it  during  the  action  of  increafed  Itimuius,  it  is  wifely  provided, 
that  the  actions  of  the  vafcular  mufcles  and  organs  of  fenfe  are 
not  much  deranged  by  fmali  variations  of  (timuius  ;  as  the  quan- 
tity of  fenforial  power  becomes  in  fome  meafure  inverfely  as  the 
quantity  of  ftimulus. 

3.  A  quantity  of  ftimulus  lefs  than  that  mentioned  above,  and 
continued  for  fome  time,  induces  pain  in  the  affected  organ,  as 
the  pain  of  cold  in  the  hands,  when  they  are  immerfed  in  fnow, 
is  owing  to  a  deficiency  of  the  ftimulation  of  heat.  Hunger  is 
ii  pain  from  the  deficiency  of  the  ftimulation  of  food.  Pain 
in  the  back  at  the  commencement  of  ague-fits,  and  the  head- 
achs  which  attend  feeble  people,  are  pains  from  defect  of  ftirn- 
wins,  and  are  hence  relieved  by  opium,  cfTential  oils,  fpirit  of  wine. 
VOL.  I.  K '  As 


66  OF  STIMULUS  SECT.  XII.  5. 4, 

As  the  pains,  which  ©riginate  from  defect  of  ftirrmlus,  only 
occur  in  thofe  parts  of  the  fyftem,  which  have  been  previoufly 
fubje&ed  to  perpetual  ftimulus  ;  and  as  an  accumulation  of  fen- 
forial  power  is  produced  in  the  quiefcent  organ  along  with  the 
pain,  as  in  cold  or  hunger,  there  is  reafon  to  believe,  that  the 
pain  is  owing  to  the  accumulation  of  fenforial  power.  For,  in 
the  locomotive  mufcles,  in  the  retina  of  the  eye,  and  other  or- 
gans of  fenfe,  no  pain  occurs  from  the  abfence  of  ftimulus,  nor 
any  great  accumulation  of  fenforial  power  beyond  their  natural 
quantity,  fince  thefe  organs  have  not  been  ufed  to  a  perpetual 
(upply  of  it.  There  is  indeed  a  greater  accumulation  occurs  in 
the  organ  of  vifion  after  its  quiefcence,  becaufe  it  is  fubje6t  to 
more  conftant  ftimulus. 

4.  A  certain  quantity  of  ftimulus  lefs  than  natural  induces 
the  moving  organ  into  feebler  and  more  frequent  contractions, 
as  mentioned  in  No.  I.  4.  of  this  Section.     For  each  contraction 
moving  through  a  lefs  fpace,  or  with  lei's  force,  that  is,  with  lefs 
expenditure  of  the  fpirit  of  animation,  is  fooner  relaxed,  and  the 
fpirit  of  animation  derived  at  each  interval  into  the  acting  fibres 
being  lefs,  thefe  intervals  likewife  become  fhorter.     Hence  the 
tremors  of  the  hands  of  people  accuftomed  to  vinous  fpirit,  till 
they  take  their  ufual  ftimulus  ;    hence  the  quick  pulfe  in  fevers 
attended  with  debility,  which  is  greater  than  in  fevers  attended 
with  ftrength -,  in  the  latter  the  puife  feldom  beats  above  120 
times  in  a  minute,  in  the  former  it  frequently  exceeds  140. 

It  muft  be  obferved  that  in  this  and  the  two  following  arti- 
cles the  decreafed  action  of  the  fyftem  is  probably  more  fre- 
quently occafioned  by  deficiency  in  the  quantity  of  fenforial 
power,  than  in  the  quantity  of  ftimulus.  Thus  thofe  feeble 
conftitutions  which  have  large  pupils  of  their  eyes,  and  all  who 
labour  under  nervous  fevers,  feem  to  owe  their  want  of  natural 
quantity  of  activity  in  the  fyftem  to  the  deficiency  of  fenforiai 
power  ;  fince,  as  far  as  can  be  feen,  they  frequently  poiTefs  the 
natural  quantity  of  ftimulus. 

5.  A  certain  quantity  of  ftimulus  lefs  than  that  above  men- 
tioned, inverts  the  order  of  tucceflive   fibrous  contractions  ;  as 
in  vomiting  the  vermicular  motions  of  the  ftomach  and  duode- 
num are  inverted,  and  their  contents  ejecled,  which  is  probably 
owing  to  the  exhauftion  of  the  fpirit  of  animation  in  the  acting 
mufcles  by  a  previous  exceilive  ftimulus,  as  by  the  root  of  ipecac- 
uanha, and   the   confequent    defect   of  feniorial   power.     The 
lame  retrograde   motions  afreet   the   whole  inteftinal  canal  in 
ileus;   and  the  cefophagus   in  globus  hyftericus.     See  this  fur- 
ther explained  in  Sedt.  XXIX.  No    1 1.  on  Retrograde  Motions. 

I  muft  obferve,  alfo,   that  fomething  fimilar  happens  in  the 

production 


SECT.  XII.  5.  6.          AND  EXERTION.  67 

production  of  our  ideas,  or  fenfual  motions,  when  they  are  too 
weakly  excited  ;  when  any  one  is  thinking  intenfely  about  one 
dung,  and  carelefsiy  oonverfmg  about  another,  he  is  liable  to  ufe 
the  word  of  a  contrary  meaning  to  that  which  he  defigned,  as 
cold  weather  for  hot  weather,  fummer  for  winter. 

6.  A  certain  quantity  of  ftimulus,  lefs  than  that  above  men- 
tioned, is  fucceededby  paralyfis,  iirit  of  the  voluntary  and  fenfi- 
tive  motions,  and  afterwards  of  thofe  of  irritation  and  of  affocia- 
tion,  which  conftitutes  death. 

VI.   Cure  of  increafed  Exertion. 

i.  The  cure,  which  nature  has  provided  for  the  increafed  ex- 
ertion  of  any  part  of  the  fyftem,  confifts  in  the  confequent  ex- 
penditure of  the  fenforial  power.  But  as  a  greater  torpor  fol- 
lows this  exhauftion  of 'fenforial  power,  as  explained  in  the  next 
paragraph,  and  a  greater  exertion  fucceeds  this  torpor,  the  con- 
ftitution  frequently  links  under  thefe  increafing  iibrations  be- 
tween exertion  and  quiefcence  ;  till  at  length  complete  quief- 
cence,  that  is,  death,  clofes  the  fcene. 

For,  during  the  great  exertion  of  the  fyftem  in  the  hot  fit  of 
fever,  an  increafe  of  ftimulus  is  produced  from  the  greater  mo- 
mentum of  the  blood,  the  greater  diftention  of  the  heart  and  ar- 
teries, and  the  increafed  produciion  of  heat,  by  the  violent  ac- 
tions of  the  lyitem  occafioned  by  this  augmentation  of  ftimulus, 
the  fenforial  power  becomes  diminifhed  in  a  few  hours  much 
beneath  its  natural  quantity,  the  veflels  at  length,  ceafe  to  obey 
even  thefe  great  degrees  of  ftimulus,  as  (hewn  in  Sect.  XL.  9. 
i.  and  a  torpor  of  the  whole  or  of  a  part  of  the  fyftem  enfues. 

Now  as  this  fecond  cold  fit  commences  with  a  greater  defi- 
ciency of  fenforial- power,  it  is  alfo  attended  with  a  greater  defi- 
ciency of  ftimuius  than  in  the  preceding  cold  fit,  that  is,  with  lefs 
momentum  of  blood,  lefs  diftention  of  the  heart.  On  this  ac- 
count the  fecond  cold  fit  becomes  more  violent  and  of  longer 
duration  than  the  firft  ;  and  as  a  greater  accumulation  of  fenlb- 
rial  power  muft  be  produced  before  the  fyitem  of  veffels  will 
again  obey  the  diminifhed  ftimulus,  it  follows,  that  the  fecond 
hot  fit  of  fever  will  be  more  violent  than  the  former  one.  And 
that  unlefs  fome  other  cauies  counteraft  either  the  violent  exer- 
tions in  the  hot  fit,  or  the  great  torpor  in  the  cold  fit,  life  will 
at  length  be  extinguifhed  by  the  expenditure  of  the  whole  of  the 
fenforial  power.  And  from  hence  it  appears,  that  the  true 
means  of  curing  fevers  muft  be  fuch  as  decreafe  the  aiftion  of 
the  fyftem  in  the  hot  fit,  and  increafe  it  in  the  cold  fit ;  that  is, 

fuch 


68  OF  STIMULUS          SECT.  XII.  6.  a. 

fuch  as  prevent  the  too  great  diminution  of  fenforial  power  in 
the  hot  fit,  and  the  too  great  accumulation  of  it  in  the  cold  one. 

2.  Where  the  exertion  of  the  fenforial  powers  is  much  in- 
creafed,  as  in  the  hot  fits  of  fever  or  inflammation,  the  follow- 
ing are  the  ufual  means  of  relieving  it.     Decreafe  the  irritations 
by  blood-letting,  and  other  evacuations  ;    by  cold  water  taken 
into  the  ftomach,  or  injected  as  an  enema,  or  ufed  externally  ; 
by  cold  air  breathed  into  the  lungs,  and  diffufed  over  the  fk-n  ; 
with  food  of  lefs  ftimulus  than  the  patient  has  been  accuilom- 
ed  to. 

3.  As  a  cold  fit,  or  paroxyfrn  of  inaclivity  of  fome  parts  of 
the  fyftem,  generally  precedes  the  hot  fit,  or  paroxyfm  of  exer- 
tion, by  which  the  fenforial  power  becomes  accumulated*  this 
cold  paroxyfm  fliould  be  prevented  by  ilimulant  medicines  and 
diet,  as  wine,  opium,  bark,  warmth,  cheerfulnefs,  anger,  furprife. 

4.  Excite  into  greater  action  fome  other  part  of  the  fyftem,  by 
which  means  the  fpirit  of  animation  may  be  in  part  expended, 
and  thence  the  inordinate  actions  of  the  difeafed  part  may  be 
leflened.     Hence  when  a  part  of  the  fkin  acts  violently,    as  of 
the  face  in  the  eruption  of  the  fmall-pox  if  the  feet  be  cold  they 
{hould  be  covered.     Hence  the  ufe  of  a  blifter  applied  near  a 
topical  inflammation.     Hence   opium  and  warm   bath  relieve 
pains  both  from  excefs  and  defect  of  ftimulus. 

5.  Firft   increafe   the  general   ftimulation   above  its  natural 
quantity,  which  may  in  fome  degree  exhauft  the  fpirit  of  ani- 
mation, and  then  decreafe  the  ftimulation  beneath  its  natural 
quantity.     Hence  after  fudorific  medicines  and  warm  air,   the 
application  of  refrigerents  may  have  greater  effect,  if  they  could 
be  adminiftered  without  danger  of  producing  too   great  torpor 
of  fome  part  of  the  fyftem  \  as  frequently  happens  to  people  in 
health  from  coming  out  of  a  warm  room  into  the  cold  air,   by 
which  a  topical   inflammation   in  confequence  of  torpor  of  the 
mucous  membrane  of  the  noftril  is  produced,  and  is  termed  a 
cold  in  the  head. 

VIL   Cure  of  decreafed  Exertion. 

I.  WHERE  the  exertion  of  the  fenforial  powers  is  much  de- 
creafed, as  in  the  cold  fits  of  fever,  a  gradual  accumulation  of 
the  fpirit  of  animation  takes  place  •,  as  occurs  in  all  cafes  where 
inaclivity  or  torpor  of  a  part  of  the  fyftem  exifts  ;  this  accumu- 
lation of  fenforial  power  increafes,  till  ftimuli  lefs  than  natural 
are  fufficient  to  throw  it  into  action,  then  the  cold  fit  ceales  ; 
and  from  the  action  of  the  natural  ftimuli  a  hot  one  fucceeds 
with  increafcd  activity  of  the  whole  fyftem. 

So 


SECT.  XII.  7.  2.        AND  EXERTION.  69 

So  in  fainting  fits,  or  fyncope,  there  is  a  temporary  deficien- 
cy of  ienforial  exertion,  and  a  confequent  quiefcence  of  a  great 
part  of  the  fyftem.  This  quiefcence  continues,  till  the  fenforial 
power  becomes  again  accumulated  in  the  torpid  organs  ;  and 
then  the  ufual  diurnal  ftimuli  excite  the  revivefcent  parts  again 
into  action  ;  but  as  this  kind  of  quiefcence  continues  but  a 
fhort  time  compared  to  the  cold  paroxylm  of  an  ague,  and  lefs 
affects  the  circulatory  fyftem,  a  lefs  fuperabundancy  of  exertion 
fucceeds  in  the  organs  previoufly  torpid,  and  a  lefs  excels  of  ar- 
terial activity.  See  Sett.  XXXIV.  i.  6. 

2  In  the  difeafes  occafioned  by  a  defect  of  fenforial  exertion, 
-as  in  cold  fits  of  ague,  hyfteric  complaint,  and  nervous  fever, 
the  following  means  are  thofe  commonly  uied.  i.  Increafe  the 
flimulation  above  its  natural  quantity  for  fome  weeks,  till  a  new 
habit  of  more  energetic  contraction  of  the  fibres  is  eftablifhed. 
This  is  to  be  done  by  wine,  opium,  bark,  fteel,  given  at  exact: 
periods,  and  in  appropriate  quantities  ;  for  if  thefe  medicines  be 
given  in  fuch  quantity,  as  to  induce  the  lead  degree  of  intoxica- 
tion, a  debility  fucceeds  from  the  ufelefs  exhauition  of  fpirit  of 
animation  in  confequence  of  too  great  exertion  of  the  mufcles 
or  organs  of  fenfe.  To  thefe  irritative  ftimuli  fliould  be  added 
the  fenfitive  ones  of  cheerful  ideas,  hope,  affection. 

3.  Change   the  kinds   of  ftimulus.     The  habits  acquired  by 
the  conftitution  depend  on  fuch  nice  circumftances,  that  whert 
one  kind  of  ftimulus  ceafes  to  excite  the   fenforial  power  into 
the  quantity  of  exertion  necefTary  to  health,  it  is  often  fufficient 
to  change  the  ftimulus  for  another  apparently  fimilar  in  quanti- 
ty and  quality.     Thus  when  wine  ceafes  to  ftimulate  the  con- 
ftitution, opium  in  appropriate  dofes  fupplies  the  defect ;  and 
the  contrary.     This  is  allo  obferved  in  the  effeds   of  cathartic 
medicines,  when  one  lofes  its  power,   another,  apparently  lefs 
efficacious,  will  fucceed.     Hence  a  change  of  diet,  drink,  and 
ftimulating  medicines,  is  often  advantageous  in  difeafes  of  de- 
bility. 

4.  Stimulate  the  organs,   whofe  motions  are  aflbciated  with 
the  torpid  parts  of  the  fyftem.     The  actions  of  the  minute  vef- 
fels  of  the  various  parts  of  the  external  fkin  are  not  only  aflbciated 
with  each  other,  but  are  ftrongly  aflbciated  with  thofe  of  fome  of 
the  internal  membranes,  and  particularly  of  the  ftomach.    Hence 
when  the  exertion  of  the  ftomach  is  lels  than  natural,  and  indi- 
geftion  and  heartburn    fucceed,    nothing  fo  certainly  removes 
thefe  fymptoms  as  the  ftimulus  of  a  blifter  on  the  back.     The 
coldnefs  of  the  extremities,  as  of  the  nofe,  ears,  or  fingers,  are 
hence  the  beft  indication  for  the  fuccefsful  applicationof  blifters. 

5.  Decreafe  the  ftimulus  for  a  time.     By  leflening  the  quan- 

tity 


70  OF  STIMULUS          SECT.  XII.  7. 6. 

tity  of  heat  for  a  minute  or  two  by  going  into  the  cold  bath,  a 
great  accumulation  of  fenforial  power  is  produced  ;  for  not  on- 
ly the  minute  vefiels  of  the  whole  external  fkm  for  a  time  be- 
come inactive,  as  appears  by  their  palenefs  ;  but  the  minute 
reffrls  of  the  lungs  lofe  much  of  their  activity  alfo  by  concert 
with  thofe  of  the  fkin,  as  appears  from  the  difficulty  of  breath- 
ing at  firft  going  into  cold  water.  On  emerging  from  the  bath 
the  fenforial  power  is  thrown  into  great  exertion  by  the  ftimu- 
lu  of  the  common  degree  of  the  warmth  of  the  atmofphere)  and 
a  great  production  of  animal  heat  is  the  confequence.  The 
longer  a  perlbn  continues  in  the  cold  bath  the  greater  mud  be 
the  pefent  inertion  of  a  great  part  of  the  fyftem,  and  in  conte- 
querice  a  greater  accumulation  of  fenforial  power.  Whence 
M.  Pon.e  recommends  fome  melancholy  patients  to  be  kept 
from  two  to  fix  hours  in  fpring-water  and  in  baths  ftill  colder. 

6.  Decreafe  the  ftimulus  for  a  time  below  the  natural,  and 
then  increafe  it  above  natural.     The  effect  of  this  procefs,  im- 
pr  perly  ufed,  is  feen  in  giving  much  food,   or  applying  much 
warmth,  to  thofe  who  have  been  previoufly  expofed  to  great 
hunger,  or  to  great  cold.     The  accumulated  fenforial  power  is 
thrown  into  fo  violent  exertion,  that  inflammations  and  mortifi- 
cations fupervene,  and  death  clofes  the  cataftrophe.     In  many 
difeafes  this  method  is  the  mod  fuccefsful  j  hence  the  bark  iu 
agues  produces  more  certain  effect  after  the  previous  exhibition 
of  emetics.     In  difeafes  attended  with  violent  pain,  opium  has 
double  the  effect,  if  venefection  and  a  cathartic  have  been  pre- 
vioufly ufed.     On  this  ieenvs  to  have  been  founded  the  fuceeff- 
ful  practice  of  Sydenham,  who  ufed  venefection  and  a  cathartic 
m  chlorofis  before  the  exhibition  of  the  bark,  fleel,  and  opiates. 

7.  Prevent  any  unneceffary  expenditure  of  fenforial  power* 
Hence  in  fevers  with  debility,  a  decumbent  pofture  is  preferred, 
with  filence,  little  light,  and  fuch  a   quantity  of  heat  as  may 
prevent  any  chill  fenfation,  or  any  coldnefs  of  the  extremities. 
The  pulfe  of  patients  in  fevers  with  debility   increafes  in  fre- 
quency about  ten  pulfations  in  a  minute  on  their  rifmg  out  of 
bed.     For  the   expenditure  of  fenforial  power  to  preferve  an 
erect  pofture  of  the  body  adds  to  the  general  deficiency  of  it, 
and  thus  affects  the  circulation. 

8.  The  longer  in  time  and  the  greater  in  degree  the  quiefcence 
or  rnertion  of  an  organ  has  been,  fo  that  it  ftill  retains  life  or 
excitablility,  the  lefs  ftimulus  fliould   at  firft  be   applied  to  it. 
The  quantity  of  ftimulation  is  a  matter  of  great  nicety  to  de- 
termine, where  the  torpor  or  quiefcence  of  the  fibres  has  been 
experienced  in  a  great  degree,  or  for  a  confiderable  time,  as  in 
eold  fits  of  the  ague,  in  continued  fevers  with  great  debility,  or 

in 


SECT.  XII.  7.  8.        AND  EXERTION.  71 

In  people  famifhed  at  fea,  or  perifhing  with  cold.  In  the  two 
lait  cafes,  very  minute  quantities  of  food  fhouid  be  firft  fuppli- 
cd,  and  very  few  additional  degrees  of  heat.  In  the  two  form- 
er cafes,  but  little  ftimulus  of  wine  or  medicine,  above  what 
they  had  been  lately  accuftomed  to,  ihould  be  exhibited,  and 
this  at  frequent  and  dated  intervals,  fo  that  the  effeft  of  one 
quantity  may  be  obferved  before  the  exhibition  of  another 

If  thefe  circumftances  are  not  attended  to,  as  the  fenforial 
power  becomes  accumulated  in  the  quiefcent  fibres,  an  inordi- 
nate exertion  takes  place  by  the  increafe  of  ftimulus  acHng  on 
accumulated  quantity  of  fenforial  power,  and  either  the  paral- 
yfis,  or  death  of  the  contra&ile  fibres  enfues,  from  the  total  ex- 
penditure of  the  fenforial  power  in  the  affefted  organ,  owing  to 
this  increaie  of  exertion,  like  the  debility  after  intoxication. 
Or,  fecondly,  the  violent  exertions  above  mentioned  produce 
painful  fenfation,  which  becomes  a  new  ftimulus,  and  by  thus 
producing  inflammation,  and  increafing  the  adtivity  of  the  fibres 
already  too  great,  fooner  exhaufts  the  whole  of  the  fenibrial 
power  in  the  acting  organ,  and  mortification,  that  is,  the  death 
of  the  part,  iupervenes. 

Hence  there  have  been  many  inftances  of  people,  whofc 
limbs  have  been  long  benumbed  by  expofure  to  cold,  who  have 
loii  them  by  mortification  on  their  being  too  haftily  brought  to 
the  fire  ;  and  of  others,  who  were  nearly  famiftied  at  fea,  who 
have  died  foon  after  having  taken  not  more  than  an  ufual  meal 
of  food.  I  have  heard  of  two  well-attefted  inftances  of  patients 
in  the  cold  fit  of  ague,  who  have  died  from  the  exhibition  of 
gin  and  vinegar,  by  the  inflami  aation  which  enfued.  And  in 
many  fevers  attended  with  debility,  the  unlimited  ufe  of  wine, 
and  the  wanton  application  of  bliiters,  I  believe,  has  deftroyed 
numbers  by  the  debility  confequent  to  too  great  ftimulaton, 
that  is,  by  the  exhauftion  of  the  fenforial  power  by  its  inordi- 
nate exertion. 

Wherever  the  leaft  degree  of  intoxication  exifts,  a  proportion* 
al  debility  is  the  coniequence  ;  but  there  is  a  golden  rule  by 
which  the  neceflary  and  ufeful  quantity  of  ftimulus  in  fevers 
with  debility  may  be  afcertained.  When  wine  or  beer  is  ex- 
hibited either  alone  or  diluted  with  water,  if  the  pulfe  becomes 
flower  the  ftimulus  is  of  a  proper  quantity  ;  and  fhould  be  re- 
peated every  two  or  three  hours,  or  when  the  pulfe  again  be- 
comes quicker. 

In  the  chronical  debility  brought  on  by  drinking  fpirituous  or 
fermented  liquors,  there  is  another  golden  rule  by  which  I  have 
fuccefsfuily  directed  the  quantity  of  fpirit  which  they  may  fafe- 
ly  leflen,  for  there  is  no  other  means  by  which  they  can  recov- 
er 


7.2  OF  STIMULUS,  &c.        SECT.  XII.  8. 

er  their  health.  It  (hould  be  premifed  that  where  the  power 
of  digeftion  in  thefe  patients  is  totally  deftroyed,  there  is  not 
much  reafon  to  expect  a  return  to  healthful  vigour. 

I  have  direfted  feveral  of  thefe  patients  to  omit  one  fourth 
part  of  the  quantity  of  vinous  fpirit  they  have  been  lately  ao 
cuftomed  to,  and  if  in  a  fortnight  their  appetite  increafes,  they 
are  advifed  to  omit  another  fourth  part ;  but  if  they  perceive 
that  their  digeftion  becomes  impaired  from  the  want  of  this 
quantity  of  fpirituous  potation,  they  are  advifed  to  continue  as 
they  are,  and  rather  bear  the  ills  they  have,  than  rifle  the  en- 
counter of  greater.  Ar  the  fame  time  flefli-meat  with  or  with- 
out fpice  is  recommended,  with  Peruvian  ;>ark  and  fteel  in  fmall 
quantities  between  their  meals,  and  a  half  a  grain  of  opium,  or  a 
grain,  with  five  or  eight  grains  of  rhubarb  at  night. 

VIII.   Conclujion. 

IT  may  be  afked,  if  ftimulus  exhaufts  the  fenforial  power, 
can  an  increafe  of  it  ever  be  ufed  with  advantage,  if  where  the 
fenforial  power  is  already  in  too  fmall  quantity  ?  We  muft  rec- 
ollect, that  the  fenforial  power  is  produced  in  the  brain  and  fpi- 
nal  marrow  by  the  fibrous  aclions  of  thofe  glands  like  other  fe- 
cretions  :  and  that  hence  an  increafed  action  of  thefe  glands  by 
an  adapted  ftimulus,  or  by  aflbciation  of  motions  may  increafe 
the  quantity  of  fenforial  power,  which  increafed  aclions  of  the 
fyftem  may  be  continued  by  habit,  after  the  ftimulus  is  with- 
drawn. Thus  fome  kinds  of  ftimuli  affett  particular  parts  of 
th-j  fyftem,  blifters  afFe£l  the  Ikin,  and  the  ftomach  by  its  af- 
ibciation  with  the  Ikin  ;  emetics  affect  the  ftomach,  cathartics 
the  inteftines  ;  and  fea-falt  the  perfpirable  glands  or  capillaries  : 
but  it  is  probable,  that  wine  and  opium  affect  the  whole  fyftem  : 
and,  when  given  in  fmall  repeated  quantities,  that  they  increafe 
the  fecretion  of  fenforial  power,  either  by  their  immediate  ftim- 
ulus or  by  aflbciation,  and  that  the  ftrength  of  convalefcents  is 
recruited,  as  they  are  thus  enabled  to  digeft  more  food,  and 
that  of  a  fomewhat  more  ftimulating  quality.  The  Peruvian 
bark,  and  arfemc,  in  the  cure  of  agues,  probably  aft  in  a  fimilar 
manner  on  the  ftomach,  and  on  the  parts  affbciated  with  it,  fo 
as  to  increafe  their  powers  of  aft  ion  ^  but  not  on  the  whole 
fyftem,  as  general  heat  is  not  produced  by  them. 


SECT. 


SECT.  XIII.  i.  r.       OF  VEGETABLE,  &c  73 


SECT.       XIII. 

* 

OF  VEGETABLE  ANIMATION. 

I.  I.  Vegetables  are  irritable  >  mimofa,  dionaa  mufcipifla.  Vegeta- 
ble fecretions.  2.  Vegetable  buds  are  inferior  animals^  are  liable 
to  greater  or  lefs  irritability.  II.  Stamens  and  piftils  of  plants 
flew  marks  of  fenftbility.  III.  Vegetables  poj/efs  fome  degree  of 
'volition.  IV.  Motions  of  plants  are  ajjbciated  like  thofe  of  ani- 
mals. V.  I.  Vegetable  Jiruclure  like  that  of  animals,  their  an- 
ther* and  fligmas  are  living  creatures  Male  flowers  of  Vallif- 
neria.  2.  Whether  vegetables  poj/efs  ideas  ?  They  have  organs 
of  fenfe,  as  of  touch  and  fme//9  and  ideas  of  external  things  ? 

1.  i.  THE  fibres  of  the  vegetable  world,  as  well  as  thofe  of 
the  animal,  are  excitable  into  a  variety  of  motions  by  irritations 
of  external  objects.     This  appears   particularly   in  the  mimofa 
or  fcnfitive  plant,  whofe  leaves  contraft  on  the  flighted  injury  ; 
the  dionrea  mufcipula,  which  was  lately  brought  over  from  the 
marfhes  of   America,  prefents  us  with  another  curious  initance 
of  vegetable  irritability  ;  its  leaves   are  armed    with  fpines  on 
their  upper   edge,   and   are   fpread   on  the  ground  around  the 
item  ;  when  an  infect  creeps  on  any  of  them  in  its  patfage  to 
the  flower  or  feed,  the  leaf  ihurs  up  like  a  Reel  rat-trap,  and  de- 
ftroys  its  enemy.     See  Botanic  Garden,  Part  II.  note  on  Silene. 

The  various  fecretions  of  vegetables,  as  of  odour,  fruit,  gum, 
refin,  wax,  honey,  feem  brought  about  in  the  fame  manner  as  in 
the  glands  of  animals  :  thet  attelefs  moifture  of  the  earth  is  con- 
verted by  the  hop  plant  into  a  bitter  juice  ;  as  by  the  caterpil- 
lar in  the  nutfhell  the  fwert  kernel  is  converted  into  a  bitter 
powder.  While  the  power  of  abforption  in  the  roots  and  barks 
of  vegetables  is  excited  into  action  by  the  fluids  applied  to  their 
mouths  like  the  lacleals  and  lymphatics  of  animals. 

2.  The  individuals  of  the  vegetable  world  may  be  confidered 
as  inferior  or  lefs  perfect  animals  ;  a  tree  is  a  congeries  of  many 
living  buds,  and  in  this   refpecl:  refembles  the  branches  of  coral- 
line, which  are  a  congeries  of  a  multitude  of  animals.     Each  of 
thefe  buds  of  a  tree  has   its  proper  leaves  or  petals  for  lungs, 
produces    its    viviparous    or   its  oviparous  offspring  in  buds  or 
feeds  ;  has  its  own  roots,  which  extending  down  the  ftem  of 
the  tree  are  interwoven  with  the  roots  of  the  other  buds,  and 
form  the  bark,  which   is  the  only  living  part  of  the  ftem,  is  an- 
nually renewed,  and   is   fuperinduced    upon    the  former  bark, 
which  then  dies,  and  with  its  fiagnated  juices  gradually  harden- 

VOL.  I.  L  ing 


74  OF  VEGETABLE  SECT.  XIII.  2. 

ing  into  wood    forms  the  concentric  circles,  which  we  fee  in 
blocks  of  timber. 

The  following  circumftances   evince  the  individuality  of  the 
buds  of  trees.     Firft,  there  are  many  trees,  whofe  whole  internal 
wood  is  periihed,  and  yet  the  branches  are  vegete  and  healthy. 
Secondly,  the  fibres  of  the  barks  of  trees  are  chiefly  longitudinal, 
refembling  roots,  as  is  beautifully  feen  in  thofe  prepared  barks, 
that  were  lately  brought  from  Otaheite.     Thirdly,  in  horizontal 
wounds  of  the  bark  of  trees,  the  fibres  of  the  upper  lip  are  al- 
ways elongated   downwards    like  roots,  but  thofe  of  the  lower 
lip  do  not  approach  to  meet  them.     Fourthly,  if  you  wrap  wet 
mofs  around  any  joint  of  a  vine,  or  cover  it  with  moift  earth, 
roots  will  (hoot  out    from  it.     Fifthly,  by  the  inoculation  or  in- 
grafting of  trees    many    fruits  are  produced    from   one  ftem. 
Sixthly,  a  new  tree  is    produced  from    a   branch  plucked  from 
an  old  one,  and  let  in  the  ground.     Whence  it  appears  that  the 
buds  cf  deciduous   trees    are   fo    many  annual  plants,  that  the 
bark  is  a   contexture   of  the  caudexes  of  each  individual  bud  ; 
which  confifts  of  a  leaf  or  plumula  at  top,  of  a  radicle  below, 
and  of  a  caudex,  which  joins  thefe  together,  and  conftitutes  the 
bark  of  the  tree,  and  that  the  internal  wood  is  of  no  other  ufe 
but  to  funport  them  in  the  air,  and  that  thus  they  refemble  the 
animal  world  in  their  individuality. 

The  irritability  of  plants,  like  that  of  animals,  appears  liable 
to  be  increafed  or  decreafed  by  habit ;  for  thofe  trees  or  fhrubs, 
which  are  brought  from  a  colder  climate  to  a  warmer,  put  out 
their  leaves  and  bloflbms  a  fortnight  fooner  than  the  indigenous 
ones. 

ProfeiTor  Kalm,  in  his  Travels  in  New  York,  obferves  that 
the  apple-trees  brought  from  England  bloflbm  a  fortnight  foon- 
er than  the  native  ones.  In  our  country  the  fhrubs,  that  are 
brought  a  degree  or  two  from  the  north,  are  obferved  to  fl«ur- 
ifh  better  than  thofe  which  come  from  the  fouth.  The  Sibe- 
rian barley  and  cabbage  are  faid  to  grow  larger  in  this  climate 
than  the  fnnilar  more  fouthern  vegetables.  And  our  hoards  of 
roots,  as  of  potatoes  and  onions,  germinate  with  lefs  heat  in 
fpring  after  they  have  been  accuflomed  to  the  winter's  cold, 
than  in  autumn  after  the  lummer's  heat. 

II  The  ftamens  and  piftils  of  flowers  (hew  evident  marks  of 
fenfibility,  not  only  from  many  of  the  flamens  and  fome  piftils 
approaching  towards  each  other  at  the  feafon  of  impregnation, 
but  from  many  of  them  clofing  their  petals  and  calyxes  during 
the  cold  parts 'of  the  day  For  this  cannot  be  afcribed  to  irri- 
tation, becaufe  cold  means  a  defect  of  the  itimulus  of  heat ; 
but  as  the  want  of  accuttomed  ilimuli  produces  pain,  as  in  cold- 

nefs, 


.  XIII.  3.  ANIMATION.  75 

nefs,  hunger,  and  thirft  of  animals,  thefe  motions  of  vegetables 
in  clofing  up  their  flowers  mud  be  afcribed  to  the  difagreeable 
fenfation,  and  not  to  the  irritation  of  cold.  Others  clofe  up 
their  leaves  during  darknefs,  which,  like  the  former,  cannot  be 
owing  to  irritation,  as  the  irritating  material  is  withdrawn. 

It  may  be  objected,  that,  when  the  petals  and  calyxes  of  flow- 
ers,  and  the  leaves  of  fome  vegetables,  clofe  in  the  night,  this 
may  be  their  natural  ftate,  like  the  clofing  of  the  eyelids  in  the 
deep  of  animals  ;  and  that  it  fhould  thence  be  afcribed  to  the 
fufpenfion  of  volition,  rather  than  to  difagreeable  fenfation. 
It  may  be  anfwered,  that  in  the  flecp  of  animals  the  clofing  of 
the  eyelids  may  not  be  the  natural  (late  of  the  part,  fince  in  the 
great  inirritability  and  infenfibility  attending  fome  fevers  the  pa- 
tients fleep  with  their  eyes  half-open,  and  in  actual  death  the 
eyes  do  not  clofe  fpontaneoufly,  and  that  hence  the  clofing  of 
the  eyelids  in  fleep  feems  to  be  in  confequence  of  our  increafed 
internal  fenfibility  to  light,  or  duft,  or  drynefs. 

And  it  is  certain,  that  the  abfence  of  the  accuftomed  quanti- 
ty of  heat  decreafes  the  aclion  of  animal  fibres,  as  is  evinced  by 
the  palenefs  of  the  fkin,  wht^n  it  is  expofed  to  great  cold  ;  and 
the  increafed  action  of  the  fubcutaneous  mufcles,  as  in  fhudder- 
ing  from  cold,  is  certainly  owing  to  the  difagreeable  fenfation 
confequent  to  the  diminution  of  the  accuftomed  irritative  mo- 
tions, as  in  Seel.  XXXII.  10.  and  Sett.  IV.  5. 

An  excefs  of  moifture  on  fome  parts  of  flowers  and  leaves 
may  occafion  a  difagreeable  fenfation,  as  when  a  drop  of  water 
gets  down  the  windpipe  into  the  lungs  of  animals,  and  may 
thus  occafion  them  to  clofe. 

The  approach  of  the  anthers  in  many  flowers  to  the  fligmas, 
and  of  the  piftils  of  fome  flowers  to  the  anthers,  mutt  be  afcri- 
bed to  the  paflion  of  love,  and  hence  belongs  to  fenfation,  not  to 
irritation. 

III.  That  the  vegetable  world  pofleffes  fome  degree  of  vol- 
untary powers,  appears  from  their  neceflity  to  fleep,  which  we 
have  fhewn  in  Seel:.  XVIII.  to  confift  in  the  temporary  abolition 
of  voluntary  power.     This  voluntary  power  feems  to  be  exerted 
in  the  circular  movement   of   the  tendrils  of  vines,  and  other 
climbing  vegetables  ;  or  in  the  efforts  to  turn  the  upper  furface 
of  their  leaves,  or  their  flowers  to  the  light. 

IV.  The  aflbciations  of  fibrous  motions  are  obfervable  in  the 
vegetable  world,  as  well  as  in  the  animal.     The  divifions  of  the 
leaves  of  the  fenfitive  plant  have  been  accuftomed  to  contract  at 
the  fame  time  from  the  abfence  of  light  ;  hence  if  by  any  other 
circumftance,  as  a  flight   ftroke  or   injury,  one  divifion  is  irrita- 
ted into  contraction,  the  neighbouring  ones  contraft  alfo,  from 

their 


76  OF  VEGETABLE         SECT.  XIII.  5.  i. 

their  motions  being  aflbciated  with  thofe  of  the  irritated  part. 
So  the  various  ftamina  of  the  clafs  of  fyngenefia  have  been  accuf- 
tomed  to  contrad;  together  in  the  evening,  and  thence  if  you 
ftimulate  one  of  them  with  a  pin,  according  to  the  experiment 
of  M.  Colvolo,  they  all  contraft  from  their  acquired  aflbciations. 
Which  aifo  (hows,  that  the  number  of  male  or  female  organs 
exifting  in  one  flower  does  not  deftroy  the  individuality  of  it  ; 
any  more  than  the  number  of  paps  of  a  bitch  or  fow,  or  vhe 
double  organ  of  a  barn-door  cock  ;  which  is  further  evinced  by 
the  anthers  and  ftigmas  of  fome  hermaphrodite  flowers  proba- 
bly receiving  their  nutriment  from  the  fame  honey-gland  or 
nefrary,  and  having  their  blood  oxygenated  by  the  fame  corol, 
while  in  the  plants  of  the  claffes  of  monecia  and  diecia  the  male 
and  female  organs  of  reprodu&ion  belong  to  different  vegetable 
beings. 

To  evince  that  the  collapfing  of  the  fenfitive  plant  is  not  ow- 
ing to  any  mechanical  vibrations  propagated  along  the  whole 
branch,  when  a  fmgle  leaf  is  (truck  with  the  finger,  a  leaf  of  it 
was  flit  with  (harp  fciflars,  and  fome  feconds  of  time  paffed  be- 
fore the  plant  feemed  fenfible  of  the  injury  ;  and  then  the  whole 
branch  collapfed  as  far  as  the  principal  ftem  :  this  experiment 
was  repeated  feveral  times  with  the  lead  poflible  impulfe  to  the 
plant. 

V.  i.  For  the  numerous  circumstances  in  which  vegetable 
buds  are  analogous  to  animals,  the  reader  is  referred  to  the  ad-» 
ditional  notes  at  the  end  of  the  Botanic  Garden,  Part  I.  It  is 
there  fhewn,  that  the  roots  of  vegetables  refemble  the  lacteal  fyf- 
tem  of  animals  :  the  fap-veffels  in  the  early  fpring,  before  their 
leaves  expand,  are  analogous  to  the  placental  veflels  of  the  fce- 
tus  ;  that  the  leaves  of  land-plants  refemble  lungs,  and  thofe  of 
aquatic  plants  the  gills  of  fifli  ;  that  there  are  other  fyftems  of 
veflels  refembling  the  vena  portarum  of  quadrupeds,  or  the  aor- 
ta of  fifli  ;  that  the  digeftive  power  of  vegetables  is  fimilar  to 
that  of  animals,  converting  the  fluids,  which  they  abforb,  into 
fugar  •,  that  their  feeds  refemble  the  eggs  of  animals,  and  their 
buds  and  bulbs  their  viviparous  offspring.  And,  laftly,  that 
the  anthers  and  ftigmas  are  real  animals,  attached  indeed  to 
their  parent  tree  like  polypi  or  coral  infects,  but  capable  of  fpon- 
taneous  motion  ;  that  they  are  affected  with  the  pailion  of 
love,  and  furnifhed  with  powers  of  reproducing  their  fpecies, 
and  are  fed  with  honey  like  the  moths  and  butterflies,  which 
plunder  their  nectaries.  See  Botanic  Garden,  Part  I.  add.  note 
XXXIX. 

The  male  flowers  of  vallifneria  approach  (till  nearer  to  appar- 
ent animality,  as  they  detach  themfelves  from  the  parent  plant, 

and 


SECT.  XIII.  5.  2.  ANIMATION.  77 

and  float  on  the  furface  of  the  water  to  the  female  ones.  Botan- 
ic Garden,  Part  II.  Art.  Vallifneria.  Other  flowers  of  the 
clafles  of  monecia  and  diecia,  and  polygamia,  difcharge  the  fe- 
cuudating  farina,  which  floating  in  the  air  is  carried  to  the  ftig- 
nia  of  the  female  flowers,  and  that  at  confiderable  diftances. 
Can  rhis  be  effected  by  any  fpecific  attraction  ?  or,  like  the  dif- 
fufion  of  the  odorous  particles  of  flowers,  is  it  left  to  the  cur- 
rents of  winds,  and  the  accidental  mifcarriages  of  it  counteract- 
ed by  the  quantity  of  its  production  ? 

2  This  leads  us  to  a  curious  inquiry,  whether  vegetables  have 
ideas  of  external  things  ?  As  all  our  ideas  are  originally  received 
by  our  fenfes  the  queftion  may  be  changed  to,  whether  vegeta- 
bles poflefs  any  organs  of  fenfe  ?  Certain  it  is,  that  'hey  poflefs 
afrnieof  heat  and  cold,  another  of  moifture  and  drvnefs,  and 
another  of  light  and  darknefs  ;  for  they  clofe  their  petals  occa- 
fionally  from  the  prefence  of  cold,  moifture,  or  darknefs.  And 
it  has  been  already  Ihewn,  that  thefe  actions  cannot  be  perform- 
ed (imply  from  irritation,  becaufe  cold  anddaiknefs  are  negative 
quantities,  and  on  that  account  feniation  or  volition  are  implied, 
and  in  confequence  a  fenforium  or  union  of  their  nerves.  So 
when  we  go  into  the  light,  we  contract  the  iris  •,  not  frorn  any 
ftimulus  of  the  light  on  the  fine  mufcles  of  the  iris,  but  from  its 
motions  being  aflbciated  with  the  fenfation  of  too  much  light  on 
the  retina  :  which  could  not  take  place  without  a  fenforium  or 
centre  of  union  of  the  nerves  of  the  iris  with  thofe  of  vifion. 
See  Botanic  Garden,  Part  I,  Canto  3.  1.  440  note. 

Befides  theie  organs  of  fenfe,  which  diftinguifh  cold,  moiiture, 
and  darknefs,  the  leaves  of  mimofa,  and  of  dionrca,  and  of  dro- 
fera,  and  the  ftamens  of  many  flowers,  as  of  the  berberry,  and 
the  numerous  clafs  of  fyngenefia,  are  fenfible  to  mechanic  im- 
pact, that  is,  they  poflefs  a  fenfe  of  touch,  as  well  as  a  common 
fenforium  ;  by  the  medium  of  which  their  mufcles  are  excited 
into  adion.  Lailly,  in  many  flowers  the  anthers,  when  mature, 
approach  the  ftigma,  in  others  the  female  organ  approaches  to 
the  male.  In  a  plant  of  collinfonia,  a  branch  of  which  is  now 
before  me,  the  two  yellow  ftamens  are  about  three  eighths  of  an 
inch  high,  and  diverge  from  each  other  at  an  angle  of  about  fif- 
teen degrees,  the  purple  ftyle  is  half  an  inch  high,  and  in  fome 
flowers  is  now  applied  to  the  ftamen  on  the  right  hand,  and  in 
others  to  that  of  the  left  ;  and  will,  I  fuppofe,  change  place  to- 
morrow in  thofe,  where  the  anthers  have  not  yet  effufed 
their  powder. 

I  afk,  by  what  means  are  the  anthers  in  many  flowers,  and 
ftigmas  in  other  flowers,  directed  to  find  their  paramours  ? 
How  do  either  of  them  know,  that  the  other  exifts  in  their  vi- 
cinity ? 


78  OF  VEGETABLE,  &c.      SECT.  XIII.  5.  2. 

cinity  ?  Is  this  curious  kind  of  ftorge  produced  by  mechanic 
attraction,  or  by  the  fenfation  of  love  ?  The  latter  opinion  is 
fupported  by  the  ftrongeft  analogy,  becaufe  a  reproduction  of 
the  fpecies  is  the  confequence  ;  and  then  another  organ  of  fenfe 
muft  be  wanted  to  direct  thefe  vegetable  amourettes  to  find 
each  other,  one  probably  analogous  to  our  fenfe  of  fmell,  which 
in  the  animal  world  directs  the  new-born  infant  to  its  fource  of 
nourimment,  and  they  may  thus  poflefs  a  faculty  of  perceiving 
as  well  as  of  producing  odours. 

Thus,  befides  a  kind  of  tafte  at  the  extremities  of  their  roots, 
fimilar  to  that  of  the  extremities  of  our  lacleal  vefiels,  for  the 
purpofe  of  felecling  their  proper  food  :  and  befides  different 
kinds  of  irritability  redding  in  the  various  glands,  which  fepa- 
rate  honey,  wax,  refin,  and  other  juices  from  their  blood  ;  vege- 
table life  feems  to  poflefs  an  organ  of  fenfe  to  diflinguifh  the  va- 
riations of  heat,  another  to  diftinguifti  the  varying  degrees  of 
moifture,  another  of  light,  another  of  touch,  and  probably  anoth- 
er analogous  to  our  fenfe  of  fmell.  To  thefe  muft  be  added  the 
indubitable  evidence  of  their  paflion  of  love,  and  I  think  we 
may  truly  conclude  that  they  are  furnifhed  with  a  common 
fenforium  belonging  to  each  bud,  and  that  they  muft  occafion- 
ally  repeat  thofe  perceptions  either  in  their  dreams  or  waking 
hours,  and  confequently  poflefs  ideas  of  fo  many  of  the  proper- 
ties of  the  external  world,  and  of  their  own  existence. 


SECT. 


SECT.  XIV.  i.          PRODUCTION,  &c.  79 

SECT.      XIV. 

•  OF    THE    PRODUCTION    OF    IDEAS. 

• 

I.  Of  material  and  immaterial  beings.  Doclrine  of  St.  Paul.  II. 
I.  Of  the  fenfe  of  touch.  Of  folidity.  2.  Of  figure.  Motion. 
Time.  Place.  Space.  Number.  3.  Of  the  penetrability  of 
matter.  4.  Spirit  of  animation  pojftffes  jolidity,  figure >  vifibility9 
£5V.  Of  fpirit s  and  angels.  5.  The  exiftence  of  external  things. 
III.  Ofvifion.  IV.  Of  hearing.  V.  Offmellandtajle.  VI. 
Of  the  organ  of  fenfe  by  which  we  perceive  heat  and  cold,  not  by 
the  fenfe  of  touch.  VII.  Of  the  fenfe  ofextenfton,  the  whole  of  the 
locomotive  mufcles  may  be  conftdered  as  one  organ  of  fenfe  VIII. 
Of the  fenfe 's  of  hunger,  thirj},  want  offrejh  air^fuckling  children^ 
and  luft.  IX.  Of  many  other  organs  of  fenfe  belonging  to  the 
glands.  Of  painful  fenfations  from  the  excefs  of  light ,  prejfure^ 
heat,  itching,  caujiics,  and  eleflricity. 

I.  PHILOSOPHERS  have  been  much  perplexed  to  underftand, 
in  what  manner  we  become  acquainted  with  the  external  world  ; 
infomuch  that  Dr.  Berkeley  even  doubted  its  exiftence,  from 
having  obferved  (as  he  thought)  that  none  of  our  ideas  refemble 
their  correfpondent  objects.  Mr.  Hume  aflerts,  that  our  belief 
depends  on  the  greater  diftinftnefs  or  energy  of  our  ideas  from 
perception  ;  and  Mr.  Reid  has  lately  contended,  that  our  belief 
of  external  objects  is  an  innate  principle  neceffarily  joined  with 
our  perceptions. 

So  true  is  the  obfervation  of  the  famous  Malbranch,  "  that 
our  fenfes  are  not  given  us  to  difcover  the  efTences  of  things, 
but  to  acquaint  us  with  the  means  of  preferving  our  exiftence," 
(L.  I.  ch.  v.)  a  melancholy  reflection  to  philofophers  ! 

Some  philofophers  have  divided  all  created  beings  into 
material  and  immaterial  ;  the  former  including  all  that  part 
of  being,  which  obeys  the  mechanic  laws  of  action  and  reaction, 
but  which  can  begin  no  motion  of  itfelf ;  the  other  is  the  caufe 
of  all  motion  and  is  either  termed  the  power  of  gravity,  or  of 
fpecific  attraction,  or  the  fpirit  of  animation.  This  immaterial 
agent  is  fuppofed  to  exift  in  or  with  matter,  but  to  be  quite  dif- 
tinct  from  it,  and  to  be  equally  capable  of  exiftence,  after  the 
matter,  which  now  poflefles  it,  is  decompofed. 

Nor  is  this  theory  ill  fupported  by  analogy,  iince  heat,  elec- 
tricity, and  magnetifm  can  be  given  to  or  taken  from  a  piece 
of  iron  ;  and  muft  therefore  exift,  whether  feparated  from  the 
metal,  or  combined  with  it.  From  a  parity  of  reafoning,  the 

fpirit 


Ro  PRODUCTION  SECT,  XIV.  2.  i. 

fpirit  of  animation  would  appear  to  be  capable  of  exifting  as  well 
feparately  from  the  body  as  with  it. 

I  beg  to  be  underftood,  that  I  do  not  with  to  difpute  about 
words,  and  am  ready  to  allow,  that  the  powers  of  gravity,  ipe- 
cific  attra6iion,  electricity,  magnetifm,  and  even  the  fpirit  of 
animation,  may  confift  of  matter  of  a  finer  kind  ;  and  to  believe, 
with  St,  Paul  and  Maibranch,  that  the  ultimate  caufe  only  of  all 
motion  is  immaterial,  that  is  God.  St.  Paul  fays,  "  in  him  we 
live  and  move,  and  have  our  being  ;"  and,  In  the  i5th  chapter 
to  the  Corinthians,  diftinguifhes  between  the  pfyche  or  living 
fpirit,  and  the  pneuma  or  reviving  fpirit.  By  the  words  fpirit 
of  animation  or  fenforial  power,  I  mean  only  that  animal  life, 
which  mankind  poflefs  in  common  with  brutes,  and  in  fome 
degree  even  with  vegetables,  and  leave  the  consideration  of  the 
immortal  part  of  us,  which  is  the  object  of  religion,  to  thofe 
who  treat  of  revelation. 

II.      i.   Of  the  Senfe  of  Touch. 

THE  firft  ideas  we  become  acquainted  with  are  thofe  of  the 
fenfe  of  touch  ;  for  the  foetus  mult  experience  fome  varieties  of 
agitation,  and  exert  fome  mufcular  action,  in  the  womb ;  and 
may  with  great  probability  be  fuppofed  thus  to  gain  fome  ideas 
of  its  own  figure,  of  that  of  the  uterus,  and  of  the  tenacity  of 
the  fluid,  that  furroumls  it,  (as  appears  from  the  fa£ts  mention- 
ed in  the  fucceedin^  Section  upon  Inftincl  ) 

Many  of  the  organs  of  fenfe  are  confined  to  a  fmall  part  of 
the  body,  as  the  noftrils,  ear  or  eye,  whilll  the  fenfe  of  touch  is 
difFufed  over  the  whole  fkin,  but  exifts  with  a  more  exquifite 
degree  of  delicacy  at  the  extremities  of  the  fingers  and  thumbs, 
and  in  the  lips.  The  fenfe  of  touch  is  thus  very  commodioufly 
difpofed  for  the  purpofe  of  encompaffing  fmaller  bodies,  ani  for 
adapting  itfelf  to  the  inequalities  of  larger  ones.  The  figure  of 
fmall  bodies  feems  to  be  learnt  by  children  by  their  lips  as  much 
as  by  their  fingers  ;  on  which  account  they  put  every  new  ob- 
je£t  to  their  mouths,  when  they  are  fatisfied  with  food,  as  well 
as  when  they  are  hungry  And  puppies  feem  to  learn  their 
ideas  of  figure  principally  by  the  lips  in  their  mode  of  play. 

We  acquire  our  tangible  ideas  of  objeds  either  by  the  fimple 
preflure  of  this  organ  of  touch  again  (t  a  folid  body,  or  by 
moving  our  organ  of  touch  along  the  furface  of  it.  In  the  former 
cafe  we  learn  the  length  and  breadth  of  the  objeft  by  the  quan- 
tity of  our  organ  of  touch,  that  is  imprefled  by  it  :  in  the  latter 
cafe  we  learn  the  length  and  breadth  of  objedlsby  the  continu- 
ance of  their  preflure  on  our  moving  organ  of  touch. 

It 


SECT.  XIV.  2. 2.  OF  IDEAS.  8 1 

It  is  hence,  that  we  are  very  flow  in  acquiring  our  tangible 
ideas,  and  very  flow  in  recollefting  them  ;  tor  if  I  now  think  of 
the  tangible  idea  of  a  cube,  that  is,  if  I  think  of  its  figure,  and 
of  the  folidity  of  every  part  of  that  figure,  I  muft  conceive  my- 
felf  as  pafTmg  my  fingers  over  it,  and  feem  in  fume  meaturt  to 
feel  the  idea,  as  I  formerly  did  the  imprefiion,  at  the  ends  of 
them,  and  am  thus  very  flow  in  diitinftiy  recollecting  it. 

When  a  body  comprefles  any  part  of  our  fenfe  of  touch,  what 
happens  ?  Firft  this  part  of  our  fenforium  undergoes  a  mechan- 
ical compreffion,  which  is  termed  a  ttimulus  ;  fecondly,  an  idea, 
or  contraction  of  a  part  of  the  organ  of  fenfe  is  excited  ;  third- 
ly, a  motion  of  the  central  parts,  or  of  the  whole  fenforium, 
which  is  termed  fenfation,  is  produced  ,  and  thefe  three  confti- 
tute  the  perception  of  folidity. 

2.   Of  Figure )  Motion ,  Time%  Place,  Space ,  Number. 

No  one  will  deny,  that  the  medulla  of  the  brain  and  nerves 
has  a  certain  figure  ;  which,  as  it  is  diffufed  through  nearly  the 
whole  of  the  body,  mult  have  nearly  the  figure  of  that  body. 
Now  it  follows,  that  the  fpirit  of  animation,  or  living  principle, 
as  it  occupies  this  medulla,  and  no  other  part,  (which  is  evinced 
by  a  great  variety  of  cruel  experiments  on  living  animals,)  it 
follows,  that  this  fpirit  of  animation  has  alfo  the  fame  figure  as 
the  medulla  above  defcribed  I  appeal  to  common  fenfe  !  the 
fpirit  of  animation  afts,  Where  does  it  aft  ?  It  acts  wherever 
there  is  the  medulla  above  mentioned  ;  and  that  whether  the 
limb  is  yet  joined  to  a  living  animal,  or  whether  it  be  recently 
detached  frum  it  \  as  the  heart  of  a  viper  or  frog  will  renew  its 
contractions,  when  pricked  with  a  pin,  for  many  minutes  of  time 
after  its  ex  left  ion  from  the  body. — Does  it  aft  any  where  clfe  ? 
— No  ;  then  it  certainly  exifts  in  this  part  of  fpace,  and  no 
where  elfe  \  that  is,  it  hath  figure  5  namely,  the  figure  of  the 
nervous  fyftem,  which  is  nearly  the  figure  of  the  body.  When 
the  idea  of  ibiidity  is  excited,  as  above  explained,  a  part  of  the 
extenfive  organ  of  touch  is  comprefled  by  fome  external  body, 
and  this  part  of  the  fentbrium  fo  comprefled  exaftly  refembles 
*n figure  the  figure  of  the  body  that  compreiTed  it.  Hence,  v\  hen 
we  acquire  the  idea  of  ibiidity,  we  acquire  at  the  fame  time  the 
idea  of  FIGURE  ;  and  this  idea  of  figure,  or  motion  of  a  part  of 
the  organ  of  touch,  exaftly  refembles  in  its  figure  the  figure  of 
the  body  that  occafions  it  ;  and  thus  exactly  acquaints  us  with 
this  property  of  the  external  world. 

Now,  as  the  whole  univerfe  with  all  its  parts  poffefles  a  cer- 
tain form  or  figure,  if  any  part  of  it  moves,  that  form  or  figure 

VOL.  I.  M 


ff *  PRODUCTION          SECT.  XIV.  2.  a. 

of  the  whole  is  varied  :  hence,  as  MOTION  is  no  other  than  a  per- 
petual variation  of  figure,  our  idea  of  motion  is  alfo  a  real  re- 
fembhnce  of  the  motion  that  produced  it. 

It  may  be  faid  in  objedion  to  this  definition  of  motion,  that 
an  ivory  globe  may  revolve  on  its  axis,  and  that  here  will  be  a 
motion  without  change  of  figure.  But  the  figure  of  the  parti- 
cle A?  on  one  fide  of  this  globe  is  not  the  fame  figure  as  the  figure 
of  y  on  the  other  fide,  any  more  than  the  particles  themfeives 
are  the  fame,  though  they  -xttfimilar  figures ;  and  hence  they 
cannot  change  place  with  each  other  without  difturbing  or 
changing  the  figure  of  the  whole. 

Our  idea  of  TIME  is  from  the  fame  fource,  but  is  more  ab- 
ilradled,  as  it  includes  only  the  comparative  velocities  of  thefe 
variations  of  figure  ;  hence  if  it  be  alked,  How  long  was  this 
book  in  printing  ?  it  may  be  anfwered,  Whilft  the  fun  was 
paffing  through  Aries. 

Our  idea  of  PLACE  includes  only  the  figure  of  a  group  of 
bodies,  not  die  figures  of  the  bodies  themfeives.  If  it  be  alked 
where  is  Nottinghamflnre,  the  anfwer  is,  it  is  furrounded  by 
Derbyfhire,  Lincolnfhire,  and  Leicefterfhire  ;  hence  place  is  our 
idea  of  the  figure  of  one  body  furrounded  by  the  figures  of  other 
bodies. 

The  idea  of  SPACE  is  a  more  abftradled  idea  of  place  exclu- 
ding the  group  of  bodies. 

The  idea  of  NUMBER  includes  only  the  particular  arrange- 
ments or  diftributions  of  a  group  of  bodies,  and  is  therefore  on- 
ly a  more  abftradled  idea  of  the  parts  of  the  figure  of  the  group 
of  bodies  ;  thus  when  I  fay  England  is  divided  into  forty  coun- 
ties, I  only  fpeak  of  certain  divisions  of  its  figure. 

H<:nce  arifes  the  certainty  of  the  mathematical  fciences,  as 
they  explain  thefe  properties  of  bodies,  which  are  exactly  re- 
fembled  by  our  ideas  of  rhem,  whilft  we  are  obliged  to  colle£fc 
almoft  all  our  ether  knowledge  from  experiment  ;  that  is,  by 
obferving  the  efFedls  exerted  by  one  body  upon  another. 

I  feel  myfelf  much  obliged  by  the  accurate  attention  given  to 
the  firft  volume  of  Zoonomia,  and  by  the  ingenious  criticifms 
bellowed  on  it,  by  the  learned  writers  of  that  article  both  in 
the  Analytical  and  Englifti  Reviews.  Some  circumftances,  in 
which  their  fentiments  do  not  accord  with  thofe  expreffed  in  the 
work,  I  intend  to  reconfider,  and  to  explain  further  at  fome  fu- 
ture time.  One  thing,  in  which  both  thefe  gentlmen  feem  to 
diifent  from  me,  I  ihall  now  mention,  it  is  concerning  the  man- 
ner, in  which  we  acquire  the  idea  of  figure  ;  a  circumftance  of 
great  importance  in  the  knowledge  of  our  intellect,  as  it  mews 
the  caufe  of  the  accuracy  ©f  our  ideas  of  motion,  time,  ipace3 

number. 


SECT.  XIV.  2.  2.  OF  IDEAS.  83 

number,  and  of  the  mathematical  fciences,  which  are  concerned 
in  the  menfurations  or  proportions  of  figure. 

This  I  imagine  may  have  in  part  arifen  from  the  prepoflef- 
fion,  which  has  almoft  univefally  prevailed,  that  ideas  are  im- 
material beings,  and  therefore  poffefs  no  properties  in  common 
with  folid  matter.  Which  I  fuppo'ed  to  be  a  fanciful  hypothefis 
like  the  ftories  of  ghofts  and  apparitions,  which  have  fo  long 
amufed,  and  dill  amufe  the  credulous  without  any  foundation 
in  nature. 

The  exiftence  of  our  own  bodies,  and  of  their  folidity,  and  of 
their  figure,  and  of  their  morions,  is  taken  for  granted  in  my 
account  of  ideas  ;  becaufe  the  ideas  themfelves  are  believed  to 
confift  of  motions  or  configurations  of  folid  fibres ;  and  the 
queftion  now  propofed  is,  how  we  become  acquainted  with  the 
figures  of  bodies  external  to  our  organs  of  fenfe  ?  Which  I  can 
only  repeat  from  what  is  mentioned  in  Se£t.  XIV.  2.  2.  t'iat 
if  part  of  an  orgnn  of  fenfe  be  (lirnulated  into  aftion,  as  of  the 
fenfe  of  touch,  that  part  fo  ftimuhted  into  aclion  muft  pofTefs 
figure,  which  mufl  be  fimilar  to  the  figure  of  the  body,  which 
ftirnulates  it. 

Another  previous  prepofleflion  of  the  mind,  which  may  have 
rendered  the  manner  of  our  acquiring  the  knowledge  of  figure 
lefs  intelligible,  may  have  arifen  from  the  common  opinion  of 
the  perceiving  faculty  refiding  in  the  head  ;  whereas  our  daily 
experience  Chews,  that  our  perception  (which  confilts  of  an  idea, 
and  of  the  pleafure  or  pain  itoccafions)  exifts  principally  in  the 
organ  of  fenfe,  which  is  Simulated  into  aftion  ;  as  every  one, 
who  burns  his  finger  in  the  candle,  mufl  be  bold  to  deny. 

When  an  ivory  triangle  is  prefTed  on  the  palm  of  the  hand, 
the  figure  of  the  furface  of  the  part  of  the  organ  of  touch  thus 
compreffed  is  a  triangle,  refembling  in  figure  the  figure  of  the 
external  body,  which  comprefTes  it.  The  a&ion  of  the  (Iimu- 
lated fibres,  which  conflitute  the  idea  of  hardnefs  and  of  figure, 
remains  in  this  part  of  the  fenforium,  which  forms  the  fenfe  of 
touch  ;  but  the  fenforial  motion,  which  confbtutes  pleafure  or 
pain,  and  which  is  excited  in  confequence  of  thefe  fibrous  mo- 
tions of  the  organ  of  fenfe,  is  propagated  to  the  central  parts  of 
the  fenforium,  or  to  the  whole  of  it ;  though  this  generally  oc- 
curs in  lets  degree  of  energy,  than  exift>  in  the  ftimulated  or- 
gan of  fenfe  ;  as  in  the  inftance  above  mentioned  of  burning  a 
finger  in  the  candle. 

Some,  who  have  efpcufed  the  doclrine  of  the  immateriality  of 
ideas,  have  ferioufly  doubted  the  exiftence  of  a  material  world, 
with  which  only  our  fenfes  acquaint  us  j  and  yet  have  affented 
to  the  exiftence  of  fpirit,  with  which  our  fenfes  cannot  acquaint 

us; 


84  PRODUCTION          SECT.  XIV.  2. 3. 

us  ;  and  have  finally  allowed,  that  all  our  knowledge  is  derived 
through  the  medium  of  our  fenfes  !  They  forget,  that  if  the 
fpirit  of  animation  had  no  properties  in  common  with  mfltter,  it 
could  neither  affect  nor  be  affected  by  the  material  body.  But 
the  knowledge  of  our  own  material  exiftence  being  granted, 
which  I  fufpecl  few  rational  perfons  will  ferioufly  deny,  the  ex- 
igence of  a  material  external  world  follows  in  courfe  ;  as  our 
perceptions,  when  we  are  awake  and  not  infane,  are  diftingufh- 
ed  from  thofe  excited  by  fenfation,  as  in  our  dreams,  and  from 
thofe  excited  by  volition  or  by  afTociation,  as  in  infanity  and 
reverie,  by  the  power  we  have  of  comparing  the  prefent  percep- 
tions of  one  fenfe  with  thofe  of  another,  as  explained  in  Seel:. 
XIV.  2.  5.  And  alfo  by  comparing  the  tribes  of  ideas,  which 
the  lymbols  of  pictures,  or  of  languages,  fuggeft  to  us  by  intui- 
tive analogy  with  our  previous  experience,  that  is,  with  the  com- 
mon courfe  of  nature.  See  Clafs  III.  2.  2.  3.  on  Credulity. 

3.    Of  the  Penetrability  of  Matter. 

The  impoflibility  of  two  bodies  exifting  together  in  the  fame 
fpace  cannot  be  deduced  from  our  idea  of  folidity,  or  of  figure. 
As  foon  as  we  perceive  the  motions  of  objects  that  furround  us, 
and  learn  that  we  pofTefs  a  power  to  move  our  own  bodies,  we 
experience,  that  thofe  objects,  which  excite  in  us  the  idea  of 
folidity  and  of  figure,  oppofe  this  voluntary  movement  of  our 
own  organs  ;  as  whilft  I  endeavour  to  comprefs  between  my 
hands  an  ivory  ball  into  a  fpheroid.  And  we  are  hence  taught 
by  experience,  that  our  own  body  and  thofe,  which  we  touch, 
cannot  exift  in  the  fame  part  of  fpace. 

But  this  by  no  means  demonftrates,  that  no  two  bodies  can 
exift  together  in  the  fame  part  of  fpace.  Galilseo  in  the  preface 
t'i  his  works  feemVto  be  of  opinion,  that  matter  is  not  impene- 
trable:  Mr  Mitchel,  and  Mr.  Bofcowich,in  his  Theoria  Philof. 
Natur.  have  efpoufed  this  hypothefis :  which  has  been  lately 
publifhed  by  Dr.  Prieftley,  to  whom  the  world  is  much  indebted 
for  fo  many  important  difcoveries  in  fcience.  (Hift.  of  Light 
and  Colours,  p.  391.)  The  uninterrupted  paflage  of  light 
through  tranfparent  bodies,  of  the  electric  sether  through  metal- 
lic and  aqueous  bodies,  and  of  the  magnetic  effluvia  through  all 
bodies,  would  feem  to  give  fome  probability  to  this  opinion. 
Hence  it  appears,  that  beings  may  exift  without  poflefiing  the 
property  of  folidity,  as  well  as  they  can  exift  without  pofTefiing 
the  properties,  which  excite  our  fmell  or  tafte,  and  can  thence 
occupy  fpace  without  detruding  other  bodies  from  it ;  but  we 
cannot  become  acquainted  with  fuch  beings  by  our  fenfe  of 

touch, 


SECT.  XIV.  2. 4-  OF  IDEAS.  85 

touch,  any  more  than  we  can  with  odours  or  flavours  without 
our  fenfes  of  fmell  and  tafte. 

But  that  any  being  can  exift  without  exifling  in  f pace,  is,  to 
my  ideas  utterly  incomprehenfible.  My  appeal  is  to  common 
fenfe.  To  be  implies  a  when  and  a  where  ;  the  one  is  com- 
paring it  with  the  motions  of  other  beings,  and  the  other  with 
their  Situations. 

If  there  was  but  one  object,  as  the  whole  creation  may  be 
confidered  as  one  objecl,  then  I  cannot  afk  where  it  exifts  ? 
for  there  are  no  other  objects  to  compare  its  fituation  with. 
Hence  if  any  one  denies,  that  a  being  exifts  in  fpace,  he  denies, 
that  there  are  any  other  beings  but  that  one  ;  for  to  anfwer  the 
queftion,  "  Where  does  it  exift  ?"  is  only  to  mention  the  fitua- 
tion  of  the  objects  that  furround  it. 

In  the  fame  manner  if  it  be  afked — "  When  does  a  being 
exift  ?"  The  aniwer  only  fpecifies  the  fucceffive  motions  either 
of  itfelf,  or  of  other  bodies;  hence  to  fay,  a  body  exifts  not  in 
time,  is  to  fay,  that  there  is,  or  was,  no  motion  in  the  world. 

4.   Of  the  Spirit  of  Animation. 

But  though  there  may  exift  beings  in  the  univerfe,  that  have 
sot  the  property  of  folidity  ;  that  is,  which  can  pofTefs  any  part 
of  fpace,  at  the  lame  time  that  it  is  occupied  by  other  bodies  ; 
yet  there  may  be  other  beings,  that  can  aflume  this  property  of 
folidity,  or  difrobe  themfelves  of  it  occafionally,  as  we  are  taught 
of  fpirits,  and  of  angels  ;  and  it  would  feem,  that  THE  SPIRIT 
OF  ANIMATION  muft  be  endued  with  this  property,  otherwife 
how  could  it  occafionally  give  motion  to  the  limbs  of  animals  ? 
— or  be  itfelf  ftimulated  into  motion  by  the  obtrufions  of  fur- 
rounding  bodies,  as  of  light,  or  odour  ? 

If  the  fpirit  of  animation  was  always  neceflarily  penetrable, 
it  could  not  influence  or  be  influenced  by  the  folidity  of  com- 
mon matter  ;  they  would  exift  together,  but  could  not  detrude 
each  other  from  the  part  of  fpace,  where  they  exift  -,  that  is, 
they  could  not  communicate  motion  to  each  other.  No  two 
things  can  influence  or  off  eel  each  other ',  which  have  not  fome  prop- 
erty common  to  both  of  them ;  for  to  influence  or  affect  another 
body  is  to  give  or  communicate  fome  property  to  it,  that  it  had 
not  before ;  but  how  can  one  body  give  that  to  another,  which 
it  does  not  poflefs  itfelf  ? — The  words  imply,  that  they  muft 
agree  in  having  the  power  or  faculty  of  pofTefling  fome  common 
property.  Thus  if  one  body  removes  another  from  the  part  of 
fpace,  that  it  poffeiTes,  it  muft  have  the  power  of  occupying 
that  fpace  itfelf :  and  if  one  body  communicates  heat  or  motion 

to 


U  PRODUCTION          SECT.  XIV.  2. 5. 

to  another,  it  follows,  that  they  have  alike  the  property  of  pof~ 
fefling  heat  or  motion. 

Hence  the  fpirit  of  animation,  at  the  time  it  communicates 
or  receives  motion  from  folid  bodies,  mult  itfelf  poflefs  fome 
property  of  folidity.  And  in  confequence  at  the  time  it  re- 
ceives other  kinds  of  motion  from  light,  it  mud  poflefs  that 
property,  which  light  poflefles,  to  communicate  that  kind  of 
motion  ;  and  for  which  no  language  has  a  name,  unlefs  it  may 
be  termed  Viability.  And  at  the  time  it  is  flimulated  into  oth- 
er kinds  of  animal  motion  by  the  particles  of  fapid  and  odorous 
bodies  affecting  the  fenfes  of  tafte  and  fmell,  it  mud  refemble 
thefe  particles  of  flavour,  and  of  odour,  in  poflefling  fome  fim- 
ilar  or  correfpondent  property  ;  and  for  which  language  has  no 
name,  unlefs  we  may  ufe  the  words  Saporofi'y  and  Odorofity 
for  thofe  common  properties,  which  are  poflefled  by  our  organs 
of  tafte  and  fmell,  and  by  the  particles  of  fapid  and  odorous 
bodies;  as  the  words  Tangibility  and  Audibility  may  exprefs 
the  common  property  poflefled  by  our  organs  of  touch,  and  of 
hearing,  and  by  the  folid  bodies,  or  their  vibrations,  which  af- 
fect thofe  organs. 

5.  Finally,  though  the  figures  of  bodies  are  in  truth  refern- 
bled  by  the  figure  of  the  part  of  the  organ  of  touch,  which  is 
ftimulated  into  motion  ;  and  that  organ  refembles  the  folid 
bodv,  which  ftimulates  it,  in  its  property  of  folidity ;  and 
though  the  fen  e  of  hearing  refembles  the  vibrations  of  external 
bodies  in  its  capability  of  being  ftimulated  into  motion  by  thofe 
vibrations  ;  and  though  our  other  organs  of  fenfe  refemble  the 
bodies  that  itimulate  them,  in  their  capability  of  being  ftimu- 
lated by  them  ;  and  we  hence  become  acquainted  with  thefe 
properties  of  the  external  world ;  vet  as  we  can  repeat  all  thefe 
motions  of  our  organs  of  fenfe  by  the  efforts  of  volition,  or  in 
confequence  of  the  fenfation  of  pleafure  or  pain,  or  by  their  af- 
fociation  with  other  fibrous  motions,  as  happens  in  our  reveries 
or  in  fleep,  there  would  ftill  appear  to  be  iome  difficulty  in 
demonftrating  the  exiftence  of  any  thing  external  to  us. 

In  our  dreams  we  cannot  determine  this  circumftance,  be- 
caufe  our  power  of  volition  is  fufpended,  and  the  (timuli  of  ex- 
ternal objects  are  excluded  ;  but  in  our  waking  hours  we  can 
compare  our  ideas  belonging  to  one  fenfe  with  thofe  belonging  to 
another,  and  can  thus  diftinguifh  the  ideas  occafioned  by  irrita- 
tion from  thofe  excited  by  fenfation,  volition  or  aflbciation. 
Thus  if  the  idea  of  the  fweetnefs  of  fugar  fhould  be  excited  in 
our  dreams,  the  whitenefs  and  hardnefs  of  it  occur  at  the  fame 
time  by  aflbciation  ;  and  we  believe  a  material  lump  of  fugar 
prefent  before  us.  But  if,  in  our  waking  hours,  the  idea  of  the 

fweetnefs 


SECT.  XIV.  3.  OF  IDEAS.  83 

fweetnefs  of  fugar  occurs  to  us,  the  ftimuli  of  furrounding  ob- 
jefts,  as  the  edge  of  the  table,  on  which  we  prefs,  or  green 
colour  of  the  grafs,  on  which  we  tread,  prevent  the  other  ideas 
of  the  hardnefs  and  whitenefs  of  the  fugar  from  being  excited 
by  afTociation.  Or  if  they  (hould  occur,  we  voluntarily  com- 
pare them  with  the  irritative  ideas,  of  the  table  or  grafs  above 
mentioned,  and  dete£t  their  fallacy.  We  can  thus  diftinguifti 
the  ideas  caufed  by  the  ftimuli  of  external  objects  from  thofe, 
which  are  introduced  by  aflbciation,  fenfation,  or  volition  ;  and 
during  our  waking  hours  can  thus  acquire  a  knowledge  of  the 
external  world.  Which  neverthelefs  we  cannot  do  in  our 
dreams,  becaufe  we  have  neither  perceptions  of  external  bodies, 
nor  the  power  of  volition  to  enable  us  to  compare  them  with 
the  ideas  of  imagination. 

III.  Of  Vifwn. 

OUR  eyes  obferve  a  difference  of  colour,  or  of  (hade,  in  the 
prominences  and  depreflions  of  objecls,  and  that  thofe  (hades 
uniformly  vary,  when  the  fenfe  of  touch  obferves  any  variation. 
Hence  when  the  retina  becomes  ftimulated  by  colours  or  (hades 
of  light  in  a  certain  form,  as  in  a  circular  fpot ;  we  know  by 
experience,  that  this  is  a  fign,  that  a  tangible  body  is  before  us  ; 
and  that  its  figure  is  refembled  by  the  miniature  figure  of  the 
part  of  the  organ  of  vifion,  that  is  thus  ftimulated. 

Here  whillt  the  ftimulated  part  of  the  retina  refem'bles  exa£l- 
ly  the  vifible  figure  of  the  whole  in  miniature,  the  various  kinds 
of  ftimuli  from  different  colours  make  the  vifible  figures  of  the 
minuter  parts  \  and  by  habit  we  inftantly  recall  the  tangible 
figures. 

J  hus  when  a  tree  is  the  objeft  of  fight,  a  part  of  the  retina 
refembling  a  flat  branching  figure  is  ftimulated  by  various  (hades 
of  colours  ;  but  it  is  by  fuggeftion,  that  the  gibbofity  of  the 
tree,  and  the  mofs,  that  fringes  its  trunk,  appear  before  us. 
Theie  are  ideas  of  fuggeftion,  which  we  feel  or  attend  to,  aflb- 
ciated  with  the  motions  of  the  retina,  or  irritative  ideas,  which 
we  do  not  attend  to. 

So  that  though  our  vifible  ideas  refemble  in  miniature  the 
outline  of  the  figure  of  coloured  bodies  in  other  refpecls  they 
ferve  only  as  a  language,  which  by  acquired  aflbciations  intro- 
duce the  tangible  ideas  of  bodies.  Hence  it  is,  that  this  fenfe 
is  fo  readily  deceived  by  the  art  of  the  painter  to  our  amute- 
ment  and  inftruftion.  The  reader  will  find  much  very  curious 
knowledge  on  this  fubjett  in  Bifiiop  Berkeley's  EfTay  on  Vifion, 
a  work  of  great  ingenuity. 

The 


S8  PRODUCTION  SECT.  XIV.  /; , 

The  immediate  object  however  of  the  fenfe  of  vifion  is  light , 
this  fluid,  though  its  velocity  is  fo  great,  appears  to  have  no  per- 
ceptible mechanical  impulfe,  as  was  mentioned  in  the  third 
Section,  but  feerns  to  ftimulate  the  retina  into  animal  motion 
by  its  tranfmiffion  through  this  pan  of  the  fenforium  :  for 
r hough  the  eyes  of  cats  or  other  animals  appear  luminous  in  ob- 
fcure  places  ;  yet  it  is  probable,  that  none  of  the  light,  which 
falls  on  the  retina,  is  reflected  from  it,  but  adheres  to  or  enters 
into  combination  with  the  choroide  coat  behind  it. 

The  combination  of  the  particles  of  light  with  opaque  bodies, 
and  therefore  with  the  choroide  coat  of  the  eye,  is  evinced  from 
the  heat  which  is  given  out,  as  in  other  chemical  combinations. 
For  the  fun-beams  communicate  no  heat  in  their  paflage  through 
tranfparent  bodies,  with  which  they  do  not  combine,  as  the  air 
continues  cool  even  in  the  focus  of  the  largeft  burning-glaires, 
which  in  a  moment  vitrifies  a  particle  of  opaque  matter. 

IV.   Of  the  Organ  of  Hearing. 

IT  is  generally  believed,  that  the  tympanum  of  the  ear  vi- 
brates mechanically,  when  expofed  to  audible  founds,  like  the 
ilrings  of  one  rnufical  inftrument,  when  the  fame  notes  are 
ilruck  upon  another.  Nor  is  this  opinion  improbable,  as  the 
mufcles  and  cartilages  of  the  larinx  are  employed  in  producing 
variety  of  tones  by  mechanical  vibrations  :  fo  the  mufcies  and 
bones  of  the  ear  feem  adapted  to  increafe  or  diminifh  the  ten- 
iion  of  the  tympanum  for  the  purpofes  of  fimilar  mechanical 
vibrations. 

But  it  appears  from  difleclion,  that  the  tympanum  is  not  the 
immediate  organ  of  hearing,  but  that,  like  the  humours  and  cor- 
nea of  the  eye,  it  is  only  of  ufe  to  prepare  the  object  for  the 
immediate  organ.  For  the  portio  mollis  of  the  auditory  nerve 
is  not  fpread  upon  the  tympanum,  but  upon  the  veftibulum,  and 
cochlea,  and  femi-circular  canals  of  the  ear ;  while  between  the 
tympanum  and  the  expaniion  of  the  auditory  nerve  the  cavity  is 
laid  by  Dr.  Cotunnus  and  Dr.  Mechel  to  be  rilled  with  water ; 
as  they  had  frequently  obferved  by  freezing  the  heads  of  dead 
animals  before  they  diflfecled  them  ;  and  water  being  a  more 
denfe  fluid  than  air  is  much  better  adapted  to  the  propagation 
of  vibration.  We  may  add,  that  even  the  external  opening  of 
the  ear  is  not  abfolutely  neceflary  for  the  perception  of  found  : 
for  fome  people,  who  from  thefe  defects  would  have  been  com- 
pletely deaf,  have  diflinguifhed  acute  or  grave  founds  by  the  tre- 
mours  of  a  flick  held  between  the  teeth  propagated  along  the 
bones  of  the  head,  (Hailer.  Phyf.T.  V.  p.  295). 

Hence 


SECT.  XIV.  5.  OF  IDEAS.  89 

Hence  it  appears,  that  the  immediate  organ  of  hearing  is 
not  affefted  by  the  particles  of  the  air  themfdves,  but  is  Simu- 
lated into  animal  motion  by  the  vibrations  of  them.  And  it  is 
probable  from  the  loofe  bones,  which  are  found  in  the  heads  of 
fome  fifties,  that  the  vibrations  of  water  are  fenfible  to  the  in- 
habitants of  that  element  by  a  fimilar  organ. 

The  motions  of  the  atmofphere,  which  we  become  acquainted 
with  by  the  fenfe  of  touch,  are  combined  with  its  folidity, 
weight,  or  vis  inertise  ;  whereas  thofe,  that  are  perceived  by 
this  organ,  depend  alone  on  its  elafticity.  But  though  the  vi- 
bration of  the  air  is  the  immediate  object  of  the  fenfe  of  hear- 
ing, yet  the  ideas,  we  receive  by  this  tenfe,  like  thofe  received 
from  light,  are  only  as  a  language,  which  by  acquired  aflbcia- 
tions  acquaints  us  with  thofe  motions  of  tangible  bodies,  which 
depend  on  their  elafticity  ;  and  which  we  had  before  learned 
by  our  fenfe  of  touch. 

V.    Of  Smell  and  of  Tafte. 

THE  objects  of  fmell  are  diflblved  in  the  fluid  atmofphere, 
and  thofe  of  tafte  in  the  faliva,  or  orher  aqueous  fluid,  for  the 
better  diffufing  them  on  their  refpeclive  organs,  which  feem  to 
be  (limulated  into  animal  motion  perhaps  by  the  chemical  af- 
finities of  thefe  particles,  which  conftitute  the  fapidity  and  odo- 
roiity  of  bodies,  with  the  nerves  of  fenfe,  which  perceive  them. 

Mr  Volta  has  lately  obferved  a  curious  circumftance  relative 
to  our  fenfe  of  tafte.  If  a  bit  of  clean  lead,  and  a  bit  of  clean 
filver  be  feparately  applied  to  the  tongue  and  palate  no  talte  is 
perceived  ;  but  by  applying  them  in  contact  in  refped  to  the, 
parts  out  of  the  mouth,  and  nearly  fo  in  refpect  to  the  parts, 
which  are  immediately  applied  to  the  tongue  and  palate,  a  fa- 
jine  or  aciduous  tafte  is  perceived,  as  of  a  fluid  like  a  ftream  of 
electricity  pading  from  one  of  them  to  the  other.  This  new 
application  of  the  fenfe  of  tafte  deierves  further  inveftigation, 
as  it  may  acquaint  us  with  new  properties  of  matter 

From  the  experiments  above  mentioned  of  Galvani,  Volta, 
Fowler,  and  others,  it  appears  that  a  plate  of  zinc  and  a  plate  of 
fiiver  have  greater  effect  than  lead  and  filver.  If  .one  edge  of  a 
plate  of  fiiver  about  the  fize  of  half  a  crown-piece  be  placed  up- 
on the  tongue,  and  one  edge  of  a  plate  of  zinc  about  the  fame 
fize  beneath  the  tongue,  and  if  their  oppofite  edges  are  then 
brought  into  contact  before  the  point  of  the  tongue,  a  tafte  is 
perceived  at  the  moment  of  their  coming  in  to  contact  ;  feconcl- 
ly,  if  one  of  the  above  plates  be  put  between  the  upper  lip  and 
the  gum  of  the  fore-teeth,  and  the  other  be  placed  under  the 

VOL.  I.  N  tongue, 


9*  PRODUCTION  SECT.  XIV.  6. 

tongue,  and  their  exterior  edges  be  then  brought  into  contact  in 
a  darkifh  room,  a  flam  of  light  is  perceived  in  the  eyes. 

Thefe  effects  I  imagine  only  (hew  the  fenfibility  of  our  nerves 
of  fenfe  to  very  fmall  quantities  of  the  eleftric  fluid,  as  it  pafles 
through  them,  for  I  fuppofc  thefe  fenfarions  are  occafioned  by 
flight  electric  (hocks  produced  in  the  following  manner.  By 
the  experiments  publiuhed  by  Mr.  Bennet,  with  his  ingenious 
doubler  of  ele£tricity,  which  is  the  greateft  difcovery  made  in 
that  fcience  fmce  the  coated  jar,  and  the  eduction  of  lightning 
from  the  ikies,  it  appears  that  zinc  was  always  found  minus, 
and  (ilver  was  always  found  plus,  when  both  of  them  were  in 
their  feparate  (late.  Hence,  when  they  are  placed  in  the  man- 
ner above  dcfcribed,  as  foon  as  their  exterior  edges  come  near- 
ly into  contact,  fo  near  as  to  have  an  extremely  thin  plate  of  air 
between  them,  that  plate  of  air  becomes  charged  in  the  fame 
manner  as  a  plate  of  coated  glafs  ;  and  is  at  the  fame  inftant 
discharged  through  the  nerves  of  tafte  or  of  fight,  and  gives  the 
feniations,  as  above  defcribed,  of  light  or  of  faporofify  ,  and  on- 
ly (hews  the  great  fenfibility  of  thefe  organs  of  fenfe  to  the  ftim- 
ulus  of  the  electric  fluid  in  fuddenly  palling  through  them. 

VI.   Of  the  Senfe  of  HeaU 

THERE  are  many  experiments  in  chemical  writers,  that  evince 
the  exigence  of  heat  as  a  fluid  element,  which  covers  and  per- 
vades all  bodies,  and  is  attracted  by  the  folutions  of  fome  of 
them,  and  is  detruded  from  the  combi«ation  of  others.  Thus 
from  the  combinations  of  metals  with  acids,  and  from  thofe 
combinations  of  animal  fluids,  which  are  termed  fecretions,  this 
fluid  matter  of  heat  is  given  out  amongft  the  neighboring  bod- 
ies \  and  in  the  folutions  of  falts  in  water,  or  of  water  in  air,  it 
is  abforbed  from  the  bodies,  that  furround  them  5  whilft  in  its 
facility  in  pafling  through  metallic  bodies,  and  its  difficulty  in 
pervading  refins  and  glafs,  it  refembles  the  properties  of  the 
electric  aura  ;  and  is  like  that  excited  by  friction,  and  feems 
like  that  to  gravitate  amongft  other  bodies  in  its  uncombined 
ftate,  and  to  find  its  equilibrium. 

There  is  no  circumitance  of  more  confequence  in  the  animal 
economy,  than  a  due  proportion  of  this  fluid  of  heat  \  for  the 
digeftion  of  our  nutriment  in  the  ftomach  and  bowels,  and  the 
proper  qualities  of  all  our  fecreted  fluids,  as  they  are  produced 
or  prepared  partly  by  animal  and  partly  by  chemical  procefles, 
depend  much  on  the  quantity  of  heat  ;  the  excefs  of  which,  or 
its  deficiency,  alike  gives  us  pain,  and  induces  us  to  avoid  the 
circumft-ances  that  occafion  them.  And  in  this  the  percep- 
tion 


SECT.  XIV,  6.  OF  IDEAS.  91 

tion  of  heat  efTentially  differs  from  the  perceptions  of  the  fenfe 
of  touch,  as  we  receive  pain  from  too  great  prefTure  of  folid 
bodies,  but  none  from  the  abfence  of  it.  It  is  hence  probable, 
that  nature  has  provided  us  with  a  fet  of  nerves  for  the  percep- 
tion of  this  fluid,  which  anaromifts  have  not  yet  attended  to. 

There  may  be  fome  difficulty  in  the  proof  of  this  afTertion  ; 
if  we  look  at  a  hot  fire,  we  experience  no  pain  of  the  optic 
nerve,  though  the  heat  along  with  the  light  mult  be  concentra- 
ted upon  it.  Nor  does  warm  water  or  warm  oil  poured  into 
the  ear  give  pain  to  the  organ  of  hearing  ;  and  hence  as  thefe 
organs  of  fenfe  do  not  perceive  fmall  excefies  or  deficiencies  of 
heat ;  and  as  heat  has  no  greater  analogy  to  the  folidity  or  to 
the  figures  of  bodies,  than  it  has  to  their  colours  or  vibrations  j 
there  feems  no  fuflicient  reafon  for  our  afcribing  the  perception 
of  heat  and  cold  to  the  fenfe  of  touch  ;  to  which  it  has  gener- 
ally been  attributed,  either  becaufe  it  is  difFufed  beneath  the 
whole  fkin  like  the  fenfe  of  touch,  or  owing  to  the  inaccuracy  of 
our  obfervations,  or  the  defeft  of  our  languages. 

There  is  another  circuniiiance  would  induce  us  to  believe, 
that  the  perceptions  of  heat  and  cold  do  not  belong  to  the  or- 
gan of  touch  ;  fince  the  teeth,  which  are  the  lead  adapted  for 
the  perceptions  of  folidity  of  figure,  are  the  moft  fenfible  to  heat  or 
cold  ;  whence  we  are  forewarned  from  fwallowing  thofe  mate- 
rials, whole  degree  of  coldnefs  or  of  heat  would  injure  our  ftom- 
achs. 

The  following  is  an  extracl:  from  a  letter  of  Dr.  R.  W.  Dar- 
win, of  Shrewfbury,  when  he  was  a  ftudent  at  Edinburgh.  "  I 
made  an  experiment  yefterday  in  our  hofpital,  which  much  fa- 
vours your  opinion,  that  the  fenfations  of  heat  and  of  touch  de- 
pend on  different  fers  of  nerves,  A  man  who  had  lately  recov- 
ered from  a  fever,  and  was  ftill  weak,  was  ftized  with  violent 
cramps  in  his  legs  and  feet ;  which  were  removed  by  opiates, 
except  that  one  of  his  feet  remained  infenfible,  Mr.  Ewart 
pricked  him  with  a  pin  in  five  or  fix  places,  and  the  patient  de- 
clared he  did  not  feel  it  in  the  leaft,  nor  was  he  fenfible  of  a  very 
fmart  pinch.  I  then  held  a  red-hot  poker  at  fome  diftance,  and 
brought  it  gradually  nearer  till  it  came  within  three  inches, 
when  he  aflerted  that  he  felt  it  quite  diftinclly.  I  fuppofe  fome 
violent  irritation  on  the  nerves  of  touch  had  caufed  the  cramps, 
and  had  left  them  paralytic  ;  while  the  nerves  of  heat,  having 
fufFered  no  increafed  ftimulus,  retained  their  irritability." 

Add  to  this,  that  the  lungs,  though  eafily  ftimulated  into  in- 
flammation, are  not  fenfible  to  heat.  See  Clafs  III.  i.  i.  10. 


VII.  Of 


02  PRODUCTION  SECT.  XIV.  7. 

VII.  -Of 'the  Senfe  of  Extenfton. 

THE  organ  of  touch  is  properly  the  fenfe  of  preflure,  but  the 
mufcular  fibres  themfelves  conititute  the  organ  of  fenfe,  that 
feels  extenfion.  The  fenfe  of  preflure  is  always  attended  with 
the  ideas  o|  the  figure  and  folidity  of  the  object,  neither  of 
which  accompany  our  perception  of  extenfion.  The  whole  fet 
of  mulcles,  whether  they  are  hollow  ones,  as  the  heart,  arteries, 
and  inteftines,  or  longitudinal  ones  attached  to  bones,  contract 
themfelves,  whenever  they  are  Simulated  by  forcible  elonga- 
tions ;  and  it  is  obfervable,  that  the  white  mufcles,  which 
conttitute  the  arterial  fyflem,  feem  to  be  excited  into  contrac- 
tion from  no  other  kinds  of  ftimuius,  according  to  the, 'experi- 
ments of  Haller.  And  hence  the  violent  pain  in  fom.e  inflam- 
mations, as  in  the  paronychia,  obtains  immediate  relief  by  cut- 
ting the  membrane,  that  was  ftretched  by  the  tumour  of  the 
fubjacent  parts. 

Hence  the  whole  mufcular  fyftem  may  be  confidered  as  one 
organ  of  fenfe,  and  the  various  attitudes  of  the  body,  as  ideas  be- 
longing to  this  organ,  of  many  of  which  we  are  hourly  con- 
fcious,  while  many  others,  like  the  irritative  ideas  of  the  other 
fenfes,  are  performed  without  our  attention. 

When  the  mufcles  of  the  heart  ceafe  to  act,  the  refluent 
blood  again  diftends  or  elongates  them  ;  and  thus  irritated  they 
contract  as  before.  The  fame  happens  to  the  arterial  fyftem, 
and  I  fuppofe  to  the  capillaries,  inteftines,  and  various  glands  of 
the  body. 

When  the  quantity  of  urine,  or  of  excrement,  diftends  the 
bladder,  or  rectum,  thole  parts  contract,  and  exclude  their  con- 
tents, and  many  other  mufcles  by  aflbciation  act  along  with 
them  •,  but  if  thefe  evacuations  are  not  foon  complied  with, 
pain  is  produced  by  a  little  further  extenfion  of  the  mufcular  fi- 
bres :  a  fimilar  pain  is  caufed  in  the  mufcles,  when  a  limb  is 
much  extended  for  the  reduction  of  diflocated  bones ;  and  in 
the  punimment  of  the  rack :  and  in  the  painful  cramps  of  the 
calf  of  the  leg,  or  of  other  mufcles,  for  a  greater  degree  of  con- 
traction of  a  mufcle,  than  the  movement  of  the  two  bones,  to 
which  its  ends  are  affixed,  will  admit  of,  muft  give  fimilar  pain 
to  that,  which  is  produced  by  extending  it  beyond  its  due 
length.  And  the  pain  from  punctures  or  incifions  arifes  from 
the  diftention  of  the  fibres,  as  the  knife  pafles  through  them  ; 
for  it  nearly  ceafes  as  foon  as  the  divifion  is  completed. 

All  thefe  motions  of  the  mufcles,  that  are  thus  naturally  ex- 
cited by  the  ftimuius  of  diftending  bodies,  are  alfo  liable  to  be 
called  into  ftvong  action  by  their  catenation  with  the  irritations 

or 


SECT,  XIV.  8.  OF  IDEAS.  $3 

or  fenfations  produced  by  the  momentum  of  the  progreflive  par- 
ticles of  blood  in  the  arteries,  as  in  inflammatory  fevers,  or  by 
acrid  fubftances  on  other  fenfible  organs,  as  in  the  itrangury,  or 
tenefmus,  or  cholera. 

We  fhall  conclude  this  account  of  the  fenfe  of  extenfion  by 
obferving,  that  the  want  of  its  object  is  attended  with  a  difagree- 
able  feniation,  as  well  as  the  excefs  of  it.  In  thole  hollow  muf- 
cles,  which  have  been  accuilomed  to  it,  this  difagreeable  fenfa- 
tion  is  called  faintnefs,  emptinefs,  and  finking ;  and,  when  it 
arifes  to  a  certain  degree,  is  attended  with  fyncope,  or  a  total 
quiefcence  of  all  motions,  but  the  internal  irritative  ones,  as 
happens  from  fudden  lofs  of  blood,  or  in  the  operation  of  tap- 
ping in  the  dropfy. 

VIIJ.  Of  the  Appetites  of  Hunger >  Thirfl^  Heat,  Extenfwn>  the  want 
of  Frefh  Air,  Animal  Love>  and  the  Suck/ing  of  Children. 

HUNGER  is  mod  probably  perceived  by  thofe  numerous  rami- 
fications of  nerves  that  are  feeri  about  the  upper  opening  of  the 
ilomach  -9  and  third  by  the  nerves  about  the  fauces,  and  the  top 
of  the  gula.  The  ideas  of  theie  fenfes  are  few  in  the  generality 
of  mankind,  but  are  more  numerous  in  thofe,  who  by  difeafe,  or 
indulgence,  defire  particular  kinds  of  foods  or  liquids. 

A  fenie  of  heat  has  already  been  fpoken  of,  which  may  with 
propriety  be  called  an  appetite,  as  we  painfully  defire  it,  when  it 
is  deficient  in  quantity. 

The  fenfe  of  extenfion  may  be  ranked  amongft  thefe  appe- 
tites, fince  the  deficiency  of  its  object  gives  difagreeable  fenfa- 
tions ;  when  this  happens  in  the  arterial  fyftem,  it  is  called  faint- 
nefs, and  feems  to  bear  fome  analogy  to  hunger  and  to  cold  ; 
which  like  it  are  attended  with  emptinefs  of  a  part  of  the  vafcu- 
lar  iyilem. 

The  fenfe  of  want  of  frefh  air  has  not  been  attended  to,  but 
is  as  diftincl:  as  the  others,  and  the  firft  perhaps  that  we  experi- 
ence after  our  nativity  ;  from  the  want  of  the  object  of  this 
fenfe  many  difeafes  are  produced,  as  the  jail-fever,  plague,  and 
other  epidemic  maladies.  Animal  love  is  another  appetite, 
which  occurs  later  in  life,  and  the  females  of  lactiferous  animals 
have  another  natural  inlet  of  pleafure  or  pain  from  the  fuckling 
their  offspring.  The  want  of  which,  either  owing  to  the  death 
of  their  progeny,  or  to  the  fafhion  of  their  country,  has  been  fa- 
tal to  many  of  the  fex.  The  males  have  alfo  peftoral  glands 
which  are  frequently  turgid  with  a  thin  milk  at  their  nativity, 
and  are  furnilhed  with  nipples,  which  erecT:  on  titillation  like 
fhofe  of  the  female  j  but  which  feem  now  to  be  of  no  further 

ufe. 


94  PRODUCTION,  &c.  SECT.  XIV.  9. 

life,  owing  perhaps  to  fome  change  which  thefe  animals  have 
undergone  in  the  gradual  progreflion  of  the  formation  of  the 
earth,  and  of  all  that  it  inhabit. 

Thefe  feven  laft  mentioned  fenfes  may  properly  he  termed 
appetites,  as  they  differ  irom  thofe  of  touch,  fight,  hearing,  tafte, 
and  fmell,  in  this  refpeft  ;  that  they  are  affected  with  pain  as 
well  by  the  defetl  of  their  objects  as  by  the  excefs  of  them, 
which  is  not  fo  in  the  latter.  Thus  cold  and  hunger  give  us 
pain,  as  well  as  an  excefs  of  heat  or  fatiety  ;  but  it  is  not  fo 
with  darknefs  and  filence, 

IX.  Before  we  conclude  this  Se&ion  on  the  organs  of  fenfe, 
we  muft  obferve,  that,  as  far  as  we  know,  there  are  many  more 
fenfes  than  have  been  here  mentioned,  as  every  gland  feems  to 
be  influenced  to  feparate  from  the  blood,  or  to  abforb  from  the 
cavities  of  the  body,  or  from  the  atmofphcre,  its  appropriated 
fluid,  by  the  ftimulus  of  that  fluid  on  the  living  gland  ;  and  not 
by  mechanical  capillary  abforption,  nor  by  chemical  affinity. 
Hence  it  appears,  that  each  of  thefe  glands  muft  have  a  peculiar 
organ  to  receive  thefe  irritations,  but  as  thefe  irritations  are  not 
fucceeded  by  fenfation,  they  have  not  acquired  the  names  of 
fenfes. 

However  when  thefe  glands  are  excited  into  motions  ftronger 
than  ufual,  either  by  the  acrimony  of  their  fluids,  or  by  their 
own  irritability  being  much  increased,  then  the  fenfation  of  pain 
is  produced  in  them  as  in  all  the  other  fenfes  of  the  body  ;  and 
thefe  pains  are  all  of  different  kinds,  and  hence  the  glands  at 
this  time  really  become  each  a  different  organ  of  fenfe,  though 
thefe  different  kinds  of  pain  have  acquired  no  names. 

Thus  a  great  excefs  of  light  does  not  give  the  idea  of  light  but 
of  pain  ;  as  in  forcibly  opening  the  eye  when  it  is  much  infla- 
med. The  great  excefs  of  preffure  or  diftention,  as  when  the 
point  of  a  pin  is  preffed  upon  our  Ikin,  produces  pain,  (and  when 
this  pain  of  the  fenle  of  detention  is  {lighter,  it  is  termed  itch- 
ing, or  tickling),  without  any  idea  of  folidity  or  of  figure  :  an 
excefs  of  heat  produces  fmarting,  of  coid  another  kind  of  pain  ; 
It  is  probable  by  this  fenfe  of  heat  the  pain  produced  by  cauftic 
bodies  is  perceived,  and  of  ele&ricity,  as  all  thefe  are  fluids,  that 
permeate,  diftend,  or  decompofe  the  parts  that  feel  them. 


SECT 


SECT.  XV.  J.i.        CLASSES  OF  IDEAS.  95 


SECT.      XV. 

OF    THE    CLASSES   OF    IDEAS. 

J.  I-  Ideas  received  in  tribes.  2.  We  combine  them  further ,  or  ab~ 
JiracJ  from  thefe  tribes.  3.  Complex  ideas  4.  Compounded 
ideas.  5.  Simple  ideas,  modes,  fubftances,  relations^  general  ideas. 
6.  Ideas  of  reflexion.  7.  Memory  and  imagination  imperfeclly 
defined.  Ideal  prefence.  Memorandum-rings.  II.  I.  Irrita- 
tive ideas.  Perception.  2.  Senfitive  ideas,  imagination.  3. 
Voluntary  ideas,  renlleElion.  4.  Ajjociated  ideas,  fuggejlion. 
III.  I.  Definitions  of  perception,  memory.  2.  Reafoning,  judg- 
ment, doubting,  diftingui/hing,  comparing,  3.  Invention.  4. 
Cwfcioufntfs.  5.  Identity.  6.  Lapfe  of  Time.  7.  Freewill. 

1.  i.   As  the  confthuent  elements  of  the  material  world  are 
only  perceptible  to  our  organs  of  fenfe  in  a  (late  of  combination  : 
it  follows  that  the    ideas  or  fenfual    motions  excited  by  them, 
are  never  received  fingly,  but  ever  with  a  greater  or  lefs  degree  of 
combination.     So  the  colours  of  bodies  or  their  hardnefles  oc- 
cur with  their  figures  :  every  fmell  and  tafte  has  its  degree  of 
pungency  as  well  as  its  peculiar  flavour :  and  each  note  in  mufic 
is  combined  with  the  tone  of  fome  inftrument.    It  appears  from 
hence,  that  we  can  be  fenfible  of  a  number  of  ideas  at  the  fame 
time,  fuch  as  the  whitenefs,  hardnefs  and  coldnefs  of  a  fnow- 
ball,   and  can  experience  at  the  fame  time  many  irritative  ideas 
of  furrounding  bodies,  which  we  do  not  attend  to,  as  mentioned 
in  SecHon  VII.  3.  2.     But  thofe  ideas  which  belong  to  the  fame 
fenfe,  feem  to  be  more  eafily  combined  into  fynchronous  tribes, 
than  thofe  which  were   not  received  by  the  fame  fenfe,  as  we 
can  more  eafily  think  of  the  whitenefs  and  figure  of  a  lump  of 
fugar  at  the  fame  time,  than  the  whitenefs  and  fweetnefs  of  it. 

2.  As  thefe  ideas,  or  fenfual  motions,  are  thus  excited  with 
greater  or  lefs  degrees  of  combination  ;    fo  we  have  a  power, 
when  we  repeat  them  either  by  our  volition  or  fenfation,  to  in- 
creafe  or  di minim  this  degree  of  combination,  that  is,  to  form 
compounded  ideas  from  thofe,  which  were  more  fimple  ;  and  ab- 
ftract  ones  from  thofe,  which  were  more  complex,  when  they 
were  firft  excited  ;  that  is,  we  can  repeat  a  part  or  the  whole  of 
thofe  fenfuai  motions,  which  did  conftitute  our  ideas  of  percep- 
tion ;  and  the  repetition  of  which  now  conftitutes  our  ideas  of 
recollection,  or  of  imagination. 

3.  Thofe  ideas,  which  we  repeat  without  change  of  the  quan- 
tity of  that  combination,  with  which  we  firft  received  them,  arc- 
called 


9<S  CLASSES  OF  IDEAS.          SECT.  XV.  r.  +. 

called  complex  ideas,  as  when  you  recollect  Weftminfter  Ab- 
bey, or  the  planet  Saturn  :  but  it  muft  be  obferved,  that  thefe 
complex  ideas,  thus  re-excited  by  volition,  fenfation,  or  aflbcia- 
tion,  are  feldom  perfect  copies  of  their  correfpondent  percep- 
tions, except  in  our  dreams,  where  other  external  objects  do  not 
detract  our  attention. 

4.  Thofe  ideas,  which  are  more  complex  than  the  natural  ob- 
jects that  firft  excited  them,  have  been  called  compounded  ideas^ 
as  when  we  think  of  a  fphinx,  or  griffin. 

5.  And  thofe  that  are  lefs   complex  than  the  correfpondent 
natural  objects,  have  been  termed  abftracted  ideas  :  thus  fweet- 
nefs,  and  whitenefs,  and  folidity,  are  received  at  the  fame  time 
from  a  lump  of  fugar,  yet  I  can  recollect  any  of  thefe  qualities 
without  thinking  of  the  others,  that  were  excited  along  with 
them.     See  Sect.  XVI.  17. 

When  ideas  are  fo  far  abftra&ed  as  in  the  above  example, 
they  have  been  termed  fimple  by  the  writers  of  metaphyfics,  and 
'feem  indeed  to  be  more  complete  repetitions  of  the  ideas  or  ien- 
fual  motions,  originally  excited  by  external  objects. 

Other  clafles  of  thefe  ideas,  where  the  abftraction  has  not  been 
fo  great,  have  been  termed,  by  Mr.  Locke,  modes,  fubftances, 
and  relations,  but  they  feem  only  to  differ  in  their  degree  of  ab- 
ftraction from  the  complex  ideas  that  were  at  firft  excited  -9  for 
as  thefe  complex  or  natural  ideas  are  themfelves  imperfect  copies 
of  their  correfpondent  perceptions,  fo  thefe  abftract  or  general 
ideas  are  only  (till  more  imperfect  copies  of  the  fame  percep- 
tions. Thus  when  I  have  feen  an  object  but  once,  as  a  rhinoce- 
ros, my  abftract  idea  of  this  animal  is  the  fame  as  my  complex 
one.  I  may  think  more  or  lefs  distinctly  of  a  rhinoceros,  but  it. 
is  the  very  rhinoceros  that  I  faw,  or  fome  part  or  property  of 
him,  which  recurs  to  my  mind. 

But  when  any  clafs  of  complex  objects  becomes  the  fubject  of 
converfation,  of  which  I  have  feen  many  individuals,  as  a  caftle 
or  an  army,  fome  property,  or  circumftance  belonging  to  it  is 
peculiarly  alluded  to  ;  and  then  I  feel  in  my  own  mind,  that  my 
abftract  idea  of  this  complex  object  is  only  an  idea  of  that  part, 
property,  or  attitude  of  it,  that  employs  the  prefent  converfation, 
and  varies  with  every  fentence  that  is  fpoken  concerning  it  SQ 
if  any  one  fhould  fay,  "  one  may  fir  upon  a  horie  fafer  than  on 
a  camel,"  rny  abftract  idea  of  the  two  animals  includes  only  an 
outline  of  the  level  back  ot  the  one,  and  the  gibbofity  on  the 
back  of  the  other.  What  noife  is  that  in  the  itreet  ? — Some 
horfes  trotting  over  the  pavement.  Here  my  idea  of  the  horfes 
includes  principally  the  fhape  and  motion  of  their  legs.  So 
alfo  the  abftract  ideas  of  goodnefs  and  courage  are  {till  more  im- 
perfect 


SECT.  XV.  i.  6.       CLASSES  OF  IDEAS.  97 

perfect  reprefentations  of  the  objefts  they  were  received  from ; 
for  here  we  abftract  the  material  parts,  and  recollect  only  the 
qualities. 

Thus  we  abftratft  fo  much  from  fome  of  our  complex  ideas, 
that  at  length  it  becomes  difficult  to  determine  of  what  percep- 
tion they  partake ;  and  in  many  inftances  our  idea  feems  to  be 
no  other  than  of  the  found  or  letters  of  the  word,  that  (lands 
for  the  collective  tribe,  of  which  we  are  faid  to  have  an  abftrafted 
idea,  as  noun,  verb,  chimxra  apparition. 

Mr.  Home  Tooke,  alfo,  in  his  Diverfions  of  Purley,  has  very 
ingenioufly  (hewn,  that  what  were  called  general  ideas,  are  in 
reality  only  general  terms ;  or  words  which  fignify  any  parts  of 
a  complex  object.  Whence  arifes  much  error  in  our  verbal 
reafoning,  as  the  fame  word  has  different  (ignifications.  And 
hence  thofe,  who  can  think  without  words,  reafon  more  accu- 
rately than  thofe,  who  only  compare  the  ideas  fuggefted  by 
words  ;  a  rare  faculty,  which  diftinguiihes  the  writers  of  phi- 
lofophy  from  thofe  of  fophiftry.  See  Cbfs  III.  2.  2.  3. 

6.  Ideas  have  been  divided  into  thofe  of  perception  and  thofe 
of  reflection,  but  as  whatever  is  perceived  mud  be  external  to 
the  organ  that  perceives  it,  all  our  ideas  muft  originally  be  ideas 
of  perception. 

7.  Others  have  divided  our  ideas  into  thofe  of  memory  and 
thofe  of  imagination  \  they  have  faid  that  a  recollection  of  ideas 
in  the  order  they  were  received  confhitutes  memory,  and  with- 
out that  order  imagination  ;   but  all  the  ideas  of  imagination,  ex- 
cepting the  few  that  are  termed  fimple  ideas,  are  parts  of  trains 
or  tribes  in  the  order  they  were  received  ;   as  if  I  think  of  a 
fphinx,  or  a  griffin,  the  fair  face,  bofom,  wings,  claws,  tail,  are 
all  complex  ideas  in   the  order  they  were  received  :   and  it  be- 
hoves the  writers,  who  adhere  to  this  definition,   to  determine, 
how  fmall  the  trains  muft  be,  that  (hall  be  called  imagination  ; 
and  how  great  thofe,  that  (hall  be  called  memory. 

Others  have  thought  that  the  ideas  of  memory  have  a  greater 
vivacity  than  thofe  of  imagination  :  but  the  ideas  of  a  perfon  in 
fleep,  or  in  a  waking  reverie,  where  the  trains  connected  with 
fenfation  are  uninterrupted,  are  more  vivid  and  diftinct  than 
thofe  of  memory,  fo  that  they  cannot  be  diftinguifhed  by  this 
criterion. 

The  very  ingenious  author  of  the  Elements  of  Criticifm  has 
defcribed  what  he  conceives  to  be  a  fpecies  of  memory,  and  calls 
it  ideal  prefence  ;  but  the  inftances  he  produces  are  the  reveries 
of  fenfation,  and  are  therefore  in  truth  connexions  of  the  imag- 
ination, though  they  are  recalled  in  the  order  they  were  received. 

The  ideas  connected  by  aflbciation  are  in  common  difcourfe 

Vox,.'!.  O  attributed 


9»  CLASSES  OF  IDEAS.        SECT.  XV.  2.  i. 

attributed  to  memory,  as  we  talk  of  memoranda m-ring-s,  and 
tie  a  knot  on  our  handkerchiefs  to  bring  fomething  into  our 
minds  at  a  diftance  of  time.  And  a  fchool-boy  who  can  repeat 
a  thoufand  unmeaning  lines  in  Lilly's  Grammar^  is  faid  to  have 
a  good  memory.  But  thefe  have  been  already  fhewn  to  belong 
to  the  clafs  of  aflbciation  ;  and  are  termed  ideas  of  fuggeftion. 

II.  Laitly,  the  method  already  explained  of  clafling  ideas  into 
thofe  excited  by  irritation,  fenfation,  volition,  or  aflbciation,  we 
hope  will  be  found   more  convenient  both  for  explaining  the 
operations  of  the  mind,  and  for  comparing  them  with  thofe  of 
the  body  ;  and  for  the  illuftration  and  the  cure  of  the  difeafes  of 
both,  and  which  we  fhall  here  recapitulate. 

i  Irritative  ideas  are  thofe,  which  are  preceded  by  irritation, 
which  is  excited  by  objefts  external  to  the  organs  of  fenfe  :  as 
the  idea  of  that  tree,  which  either  I  attend  to,  or  which  I  (hun 
in  walking  near  it  without  attention,  In  the  former  cafe  it  is 
termed  perception,  in  the  latter  it  is  termed  {imply  an  irritative 
idea. 

2.  Sensitive  ideas  are  thofe,  which  are  preceded  by  the  fen- 
fation of  pleafure   or  pain  ;  as  the  ideas,  which  conflitute  our 
dreams  or  reveries  ;    his  is  called  imagination. 

3.  Voluntary  ideas  are  thofe,  which  are  preceded  by  voluntary- 
exertion,  as  when  I  repeat  the  alphabet  backwards :  this  is  call- 
ed recollection. 

4.  AiTociate  ideas  are   thofe,  which  are  preceded  by  other 
ideas  or  mufcular  motions,  as  when  we  think  over  or  repeat  the 
alphabet  by  rote  in  its  ufual  order  ;  or  (ing  a  tune  we  are  accuf- 
tomed  to  :  this  is  called  fuggefbion. 

III.  i.  Perceptions  fignify  thofe  ideas,  which are  preceded  by 
irritation  and  iucceeded  by  the  fenfation  of  pleafure   or  pain, 
for  whatever  excites  our  attention  interefts  us  ;  that  is,  it  is  ac- 
companied with  pleafure  or  pain ;  however  flight  may  be  the 
degree  or  quantity  of  either  of  them. 

The  word  memory  includes  two  clafles  of  ideas,  either  thofe 
which  are  preceded  by  voluntary  exertion,  or  thofe  which  are 
fuggeiled  by  their  aflbciations  with  other  ideas. 

2.  Reafoning  is  that  operation  of  the  fenforium,  by  which  we 
excite  two  or  many  tribes  of  ideas  :  and  then  re  excite  the  ideas, 
in  which  they  differ,  or  correfpond.     If  we  determine  this  differ- 
ence, it  is  called  judgment  :  if  we  in  vain  endeavour  to  deter- 
mine it,  it  is  called  doubting. 

If  we  re-excite  the  ideas  in  which  they  differ,  it  is  called 
diftinguifhing.  If  we  re-excite  thofe  in  which  they  correfpond, 
it  is  called  comparing. 

3.  Invention  is  an  operation  of  the  fenforium,  by  which  we 

voluntarily 


SECT.  XV.  3. 4.       CLASSES  OF  IDEAS.  99 

voluntarily  continue  to  excite  one  train  of  ideas,  fuppofe  the  de- 
fign  of  raifing  water  by  a  machine  ;  and  at  the  fame  time  attend 
to  all  other  ideas,  which  are  connected  with  this  by  every  kind 
of  catenation  ;  and  combine  or  feparate  them  voluntarily  for  the 
purpofe  of  obtaining  fome  end. 

For  we  can  create  nothing  new,  we  can  only  combine  or  fepa- 
rate the  ideas,  which  we  have  already  received  by  our  percep- 
tions:  thus  if  I  wifh  to  reprefent  a  monfter,  I  call  to  my  mind 
the  ideas  of  everything  difagreeable  and  horrible,  ;md  combine 
the  naftinefs  and  gluttony  of  a  hog,  the  ftupidity  and  obftinacy 
of  an  afs,  with  the  fur  and  awkwardnefs  of  a  bear,  and  call  the 
new  combination  Caliban.  Yet  fuch  a  monfter  may  exift  in 
nature,  as  all  his  attributes  are  parts  of  nature.  So  when  I  ui(h 
to  reprefent  every  thing,  that  is  excellent  and  amiable  ;  when  I 
combine  benevolence  with  cheerfulnefs,  wiidom,  knowledge, 
tafte,  wit,  beauty  of  perfon,  and  elegance  of  manners,  and  a  fib- 
ciate  them  in  one  lady  as  a  pattern  to  the  world,  it  is  called  in- 
vention ;  yet  fuch  a  perfon  may  exift, — fuch  a  perfon  does  ex> 
ift  ! — It  is ,  who  is  as  much  a  monfter  as  Caliban. 

4.  In  refpecl  to  confcioufnef?,  we  are  only  confciotis  of  our 
exiftence,  when  we  think  about  it  ;  as  we  only  perceive  the 
lapfe  of  time,  when  we  attend  to  it  ;  when  we  are  bufied  about 
other  objedls,  neither  the  lapfe  of  time  nor  the  confcioufnefs  of 
our  own  exiftence  can  occupy  our  attention.     Hence,  when  we 
think  of  our  own  exigence,  we  only  excite  abftracled  or  reflex; 
ideas,  (as  they  are  termed),  of  our  principal  pieatures  or  pains,  of 
our  defires  or  averfions,  or  of  the  figure,  foJidity,    colour,    or 
other  properties  of  our  bodies,  and  call  that  ad  of  the  fenfori- 
um  a  confcioufnefs  of  our  exiftence.     Some  philoibpher,  I  be- 
lieve it  is  Des   Cartes,  has  faid   "  I  think,  therefore,  I  exift."  ' 
But  this  is  not  right  reafoning,  becaufe  thinking  is  a  mode  of 
exiftence  ;    and  it  is  thence  only  faying,  "  I  exift,  therefore  I 
exift."     For  there  are  three  modes  of  exiftence,  or  in  the   lan- 
guage of  grammarians  three  kinds  of  verbs      Fivft,  (imply  I  am, 
or  exift.     Secondly,  I  am  acling,  or  exift  in  a  ftate  of  activity, 
as  I  move.     Thirdly,  I  am  fuffering,  or  exift  in  a  ftare  of  being 
acled  upon,  as  lam  moved.     The  when,  and  the  where,  as  ap- 
plicable to  this  exiftence,  depends  on  the  fucceflive  motions  cf 
our  own  or  of  other  bodies;    and  on  their  refpective  fuuations, 
as  fpoken  of,  Seel  XIV.  2.  5. 

5.  Our  identity  is  known  by  our  acquired  habits  or  catenated 
trains  of  ideas  and  mufcular  motions  ;  and  perhaps,  when  we 
compare  infancy  with  old  age,  in  thofe  alone  can  our  identity  be 
fuppofed  ro  exift.     For  what  elfe  is  there  of  fimilitude  between 
thefirft  fpeck  of  living  entity  and  the  mature  man  ? — every  de- 
duction 


lod  CLASSES  OF  IDEAS.       SECT.  XV.  3.  6. 

du&ion  of  reafoning,  every  fentiment  or  paffion,  with  every  fibre 
of  the  corporeal  part  of  our  fyftem,  has  been  fubject  almoft  to 
annual  mutation  ;  while  fome  catenations  alone  of  our  ideas  and 
mufcular  a&ions  have  continued  in  part  unchanged. 

By  the  facility  with  which  we  can  in  our  waking  hours  vol- 
untarily produce  certain  fucceflive  trains  of  ideas,  we  know  by 
experience,  that  we  have  before  reproduced  them  ;  that  is,  we 
are  confcious  of  a  time  of  our  exiflence  previous  to  the  prefent 
time ;  that  is,  of  our  identity  now  and  heretofore.  It  is  thefe 
habits  of  aclion,  thefe  catenations  of  ideas  and  mufcular  mo- 
tions, which  begin  with  life,  and  only  terminate  with  it ;  and 
which  we  can  in  fome  meafure  deliver  to  our  pofterity  ;  as  ex- 
plained in  Sea.  XXXIX. 

6.  When  the  progreflive  motions  of  external  bodies  make  a 
part  of  our  prefent  catenation  of  ideas,  we  attend  to  the  lapfe  of 
time  :  which  appears  the  longer,  the  more  frequently   we  thus 
attend  to  it ;  as  when  we  expetl  fomething  at  a  certain  hour, 
which  much  interefts  us,  whether  it  be  an  agreeable  or  difagree- 
able  event ;  or  when  we  count  the  pafling  feconds  on  a  ilop- 
watch. 

When  an  idea  of  our  own  perfon,  or  a  reflex  idea  of  our 
pleasures  and  pains,  defires  and  averfions,  makes  a  part  of*  this 
catenation,  it  is  termed  conicioufnefs  ;  and  if  this  idea  of  con- 
fcioufnefs  makes  a  part  of  a  catenation,  which  we  excite  by  rec- 
ollection, and  know  by  the  facility  with  which  we  excite  it,  that 
we  have  before  experienced  it,  it  is  called  identity,  as  explained 
above. 

7.  In  refpecl;  to  freewill,  it  is  certain,  that  we  cannot  will  to 
think  of  a  new  train  of  ideas,  without  previoufly  thinking  of  the 
firft  link  of  it ;   as  I  cannot  will  to  think  of  a  black  fwan,  with- 
out previoufly  thinking  of  a  black  fwan.     But  if  I  now  think  of 
a  tail,  I  can  voluntarily  recollect  all  animals,  which  have  tails  ; 
my  will  is  fo  far  free,  that  I  can  purfue  the  ideas  linked  to  this 
idea  of  tail,  as  far  as  my  knowledge  of  the  fubject  extends  ;  but 
to  will  without  motive  is  to  will   without   defire  or  averfion  ; 
which  is  as  abfurd  as  to  feel  without  pleafure  or  pain  \  they  are 
both  folecifms  in  the  terms.     So  far  are  we  governed  by  the 
catenations  of  motions,  which  affect  both  the  body  and  the  mind 
of  man,  and  which  begin  with  our  irritability,  and  end  with  it. 


SECT. 


SECT.  XVI.  i.  OF  INSTINCT.  i  o  i 


SECT.      XVI. 

OF    INSTINCT. 

HAUD  EQUIDEM   CREDO,  QUIA   S'T  D1V1NITUS   ILLIS 
INGEN1UM,  AUT  RERUM    FATO  PRUDENTIA    MAJOR. 

VIRG.  GEORG.   I,  L.  415. 

I.  Injlinflive  aclions  defined.  Of  connate  pajfflons.  II.  Of  the  fen- 
fations  and  motions  of  the  foetus  in  the  womb.  III.  Some  animals 
are  more  perfeclly  formed  than  others  before  nativity.  Qf  learn- 
ing to  walk.  IV.  Of  thefwaliowing,  breathing,  fucking,  pecking) 
and  lapping  of  young  animals.  V.  Of  the  fenfe  of  fmell,  and  its 
ufes  to  animals.  Why  cats  do  not  eat  their  kittens.  VI.  Of  the 
accuracy  of  fight  in  mankind,  and  their  fenfe  of  beauty.  Of  the 
fenfe  of  touch  in  elephants,  monkies,  beavers ,  men.  VII.  Of  nat- 
ural language.  VIII.  The  origin  of  natural  language  ;  I .  the 
language  of  fear  ;  2.  of  grief ;  3 .  of  tender  pleafure  ;  4.  offe* 
rene  pleafure ;  $•  of  anger  ;  6.  of  attention.  IX.  Artificial  lan- 
guage of  turkies,  hens,  ducklings,  wagtails,  cuckoos,  rabbits,  dogs, 
*nd  nightingales.  X.  Of  mufic  ;  of  tooth-  edge  $  of  a  good  ear  ; 
of  architecture.  XL  Of  acquired  knowledge  ;  of  foxes ',  rooks, 
fieldfares,  lapwings,  dogs,  cats,  horfes,  crows,  pelicans,  the  tiger, 
and  rattlefnake.  XII.  OJ  birds  of  paffage,  dormice,  fnakcs,  bats, 
f wallows  quails,  ring-doves,  the  flare,  chaffinch,  hoopoe ',  chatterer, 
hawfinch,  crofs-bill,  rails  and  cranes.  XilL  Of  bird's  nefts ;  of 
the  cuckoo  ;  of  f wallow* s  nefls  ;  of  the  taylor  bird.  XIV.  Of  the 
old  joldier  ;  of  haddocks,  cods,  and  dog-fifo  ;  of  the  remora  ;  of 
crabs,  herrings,  and falmon.  XV  Offpiders,  caterpillars,  ants, 
and  the  ichneumon.  XVI.  I.  Of  locujls,  gnats  ;  2.  bees  ;  3. 
dormice,  flies,  worms,  ants,  and  wafps.  XVII.  Of  the  faculty 
that  diftinguiJJjes  man  from  the  brutes. 

I.  ALL  thofe  internal  motions  of  animal  bodies,  which  con- 
tribute to  digefl  their  aliment,  produce  their  fecretions,  repair 
their  injuries,  or  increafe  their  growth,  are  performed  without 
our  attention  or  confcioufnefs.  They  exift  as  well  in  our  fleep, 
as  in  our  waking  hours,  as  well  in  the  fcetus  during  the  time 
©f  geftation,  as  in  the  infant  after  nativity,  and  proceed  with 
aqual  regularity  in  the  vegetable  as  in  the  animal  fyftem.  Thefe 
motions  have  been  (hewn  in  a  former  part  of  this  work  to  de- 
pend on  the  irritations  of  peculiar  fluids,  and  as  they  have  never 
been  clafted  amongft  the  inftindive  aclions  of  animals,  are  pre- 
cluded from  our  prefent  difquifition. 

But 


io2  OF  INSTINCT.  SECY.  XVI.  2. 

But  all  thofc  actions  of  men  or  animals,  that  are  attended 
with  confcioufnefs,  and  feem  neither  to  have  been  dire&ed  by 
their  appetites,  taught  by  their  experience,  nor  deduced  from  ob- 
fervation  or  tradition,  have  been  referred  to  the  power  of  in- 
flindl:.  And  this  power  has  been  explained  to  be  a  divine  fome- 
thing)  a  kind  of  infpiration  ;  whilft  the  poor  animal,  that  pofiefT- 
es  it,  has  been  thought  little  better  than  a  machine  ! 

The  irkfomenefs,  that  attends  a  continued  attitude  of  the  body, 
or  the  pains  >  that  we  receive  from  heat,  cold,  hunger,  or  other 
injurious  circumftances,  excite  us  to  general  locomotion ;  and  our 
fenfes  are  fo  formed  and  conftituted  by  the  hand  of  nature,  that 
certain  objefts  prefent  us  with  pleafure,  others  with  pain,  and 
we  are  induced  to  approach  and  embrace  thefe,  to  avoid  and 
abhor  thofe,  as  fuch  tenfations  direft  us. 

Thus  the  palates  of  fome  animals  are  gratefully  affected  by  the 
maftication  of  fruits,  others  of  grains,  and  others  of  flsfh  ;  and 
they  are  thence  mitigated  to  attain  and  confurne  thofe  materials  ; 
and  are  furniflied  with  powers  of  rnufcular  motion,  and  of  di- 
geftion  proper  for  fuch  purpofes. 

Thtk/enfations  and  defires  conftitute  a  part  of  our  fyftem,  as 
our  mufcles  and  bones  conftitute  another  part :  and  hence  they 
may  anke  be  termed  natural  or  connate  ;  but  neither  of  them  can 
properly  be  termed  injhnftive  ;  as  the  word  inftin^t,  in  its  ufual 
acceptation,  refers  only  to  the  aftions  of  animals,  as  above  ex- 
plained ;  the  origin  of  thefe  aftions  is  the  fubjed  of  our  prefent 
inquiry 

Tiie  reader  is  entreated  carefully  to  attend  to  this  definition 
of  inJlinBive  aBions^  left  by  ufing  the  word  inftincl:  without  ad- 
joining any  accurate  idea  to  it,  he  may  not  only  include  the  nat- 
ural defires  of  love  and  hunger,  and  the  natural  fenfations  of 
pain  or  pieaiure,  but  the  figure  and  contexture  of  the  body,  and 
the  faculty  of  reafon  itfelf,  under  this  general  term. 

II.  We  experience  fome  fenfation,  and  perform  fome  ac- 
tions before  our  nativity;  the  fenfations  of  coW  and  warmth, 
agitation  and  relt,  fulnefs  and  inanition,  are  inftances  of  the 
former ;  and  the  repeated  ftruggles  of  the  limbs  of  the  foetus, 
which  begin  about  the  middle  of  geftation,  and  thofe  motions 
by  which  it  frequently  wraps  the  umbilical  chord  around  its 
neck  or  body,  and  even  fometimes  ties  it  in  a  knot ;  are  inftan- 
ces of  the  latter.  (Smellie's  Midwifery,  Vol.  I.  p.  182.) 

By  a  due  attention  to  thefe  circumftances  many  of  the  ac- 
tions of  young  animals,  which  at  firft  fight  feemed  only  referable 
to  an  inexplicable  inftinft,  will  appear  to  have  been  acquired  like 
•all  other  animal  actions,  that  are  attended  with  conicioufnefs$ 

iy 


SECT.  XVI.  3.  OF  INSTINCT.  103 

by  the  repeated  e forts  of  our  mufcles  under  the  conduft  of  ourfenfa- 
tlons  or  defires. 

The  chick  in  the  (hell  begins  to  move  its  feet  and  legs  on 
the  fixth  day  of  incubation  (Mattreican,  p.  138);  or  on  the 
feventh  day,  (Langley) ;  afterwards  it  is  feen  to  move  itfelf 
gently  in  the  liquid  that  furrounds  it,  and  to  open  and  (hut  its 
mouth,  (Harvei,  de  Generat  p.  62,  and  197.  Form.  dePoulet. 
ii  p  129).  Puppies  before  the  membranes  are  broken,  that 
involve  them,  are  feen  to  move  themfelves,  to  put  out  their 
tongues,  and  to  open  and  {hut  their  mouths,  (Harvey,  Gipibn, 
Riolan,  Haller).  And  calves  lick  themfelves,  and  fwallow  many 
of  their  hairs,  before  their  nativity,  which  however  puppies  do 
not,  (Swammerdam,  p.  319.  Flemyng  Phil.  Tranf.  Ann.  1755. 
42).  And  towards  the  end  of  geflation,  the  fcetufes  of  all  ani- 
mals are  proved  to  drink  part  of  the  liquid  in  which  they  fwim, 
(Haller.  Phyfiol.  T.  8.  204).  The  white  of  egg  is  found  in 
the  mouth  and  gizzard  of  the  chick,  and  is  nearly  or  quite 
confumed  before  it  is  hatched,  (Harvei  de  Generat.  58).  And 
the  liquor  amnii  is  found  in  the  mouth  and  ftomach  of  the  human 
fcerus,  and  of  calves ;  and  how  elfe  ihould  that  excrement  be 
produced  in  the  inteftines  of  all  animals,  which  is  voided  in 
great  quantity  foon  after  their  birth  j  (Gipfon  Med.  Effays, 
Edinb.  V.  i.  13  Halleri  Phyfiolo^.  T.  3  p.  318.  and  T.  8.) 
In  the  flomach  of  a  calf  the  quantity  of  this  liquid  amounted  to 
about  three  pir.ts,  and  the  hairs  amongft  it  were  of  the  fame  col- 
our with  thofe  on  its  fkin,  (Blafii  Anat.  Animal,  p.  m  122). 
Thefe  facls  are  attefted  by  many  other  writers  of  credit,  befides 
thofe  above  mentioned. 

III.  It  has  been  deemed  a  furprifing  inftance  of  inftinft,  that 
calves  and  chickens  (hould  be  able  to  walk  by  a  few  efforts  ai- 
med immediately  after  their  nativity  :  whilft  the  human  infant 
in  thofe  countries  where  he  is  not  encumbered  with  clothes,  as 
in  India,  is  five  of  fix  months,  and  in  our  climate  almoft  a 
twelvemonth,  belbre  he  can  fafely  ftand  upon  his  feet. 

The  llruggles  of  all  animals  in  the  wcmb  muft  referable  their 
mode  of  fwimming,  as  by  this  kind  of  motion  they  can  beft 
change  their  attitude  in  water.  But  the  fwimming  of  the  calf 
and  chicken  refembles  their  manner  of  walking,  which  they  have 
thus  in  part  acquired  before  their  nativity,  and  hence  accomplifli 
it  afterwards  with  very  few  efforts,  whilft  the  fwimming  of  the 
human  creature  refembles  that  of  the  frog,  and  totally  differs 
from  his  mode  of  walking. 

There  is  another  circumftance  to  be  attended  to  in  this  affair, 
that  not  only  the  growth  of  thofe  peculiar  parts  of  animals, 
which  are  firft  wanted  to  fecure  their  fubfiftence,  are  in  general 

furtheft 


io4  OF  INSTINCT.  SECT.  XVI.  4. 

furtheft  advanced  before  their  nativity  :  but  fome  animals  come 
into  the  world  more  completely  formed  throughout  their  whole 
fyftem  than  others  ;  and  are  thence  much  forwarder  in  all  their 
habits  of  motion.  Thus  the  colt,  and  the  lamb,  are  much  more 
perfe£t  animals  than  the  blind  puppy,  and  the  naked  rabbit ;  and 
the  chick  of  the  pheafant,  and  the  partridge,  has  more  perfedt 
plumage,  and  more  perfe£t  eyes,  as  well  as  greater  aptitude  to 
locomotion,  than  the  callow  neillings  of  the  dove,  and  of  the 
wren.  The  parents  of  the  former  only  find  it  neceflary  to  (hew 
them  their  food,  and  teach  them  to  take  it  up  ;  whilft  thofe  of 
the  latter  are  obliged  for  many  days  to  obtrude  it  into  their 
gaping  mouths. 

IV.  From  the  facts  mentioned  in  No.  2.  of  this  Section,  it  is 
evinced  that  the  foetus  learns  to  f wallow  before  its  nativity  ; 
for  it  is  feen  to  open  its  mouth,  and  its  ftoinach  is  found  filled 
with  the  liquid  that  furrounds  it.  It  opens  its  mouth,  either 
inftigated  by  hunger,  or  by  the  irkfomenefs  of  a  continued  at- 
titude of  the  mufcles  of  its  face  j  the  liquor  amnii,  in  which  it 
fwims,  is  agreeable  to  its  palate,  as  it  confifts  of  a  nourishing 
material,  (Haller.  Phyf.  T.  8.  p.  204).  ,  It  is  tempted  to  expe- 
rience its  tafte  further  in  the  mouth,  and  by  a  few  efforts  learns 
to  fwallow,  in  the  fame  manner  as  we  learn  all  other  animal  ac- 
tions, which  are  attended  'with  confcioufnefs,  by  the  repeated  ef- 
forts of  our  mufcles  under  the- conduct  of  our  fenfations  or  volitions. 

The  infpiration  of  air  into  the  lungs  is  fo  totally  different 
from  that  of  fwallowing  a  fluid  in  which  we  are  immerfed,  that 
it  cannot  be  acquired  before  our  nativity.  But  at  this  time, 
when  the  circulation  of  the  blood  is  no  longer  continued  through 
the  placenta,  that  fuffbcating  fenfation,  which  we  feel  about  the 
precordia,  when  we  are  in  want  of  frefh  air,  difagreeably  af- 
fects the  infant  :  and  all  the  mufcles  of  the  body  are  excited 
into  action  to  relieve  this  opprefiion  ;  thofe  of  the  breaft,  ribs, 
and  diaphragm  are  found  to  anfwer  this  purpofe,  and  thus  ref- 
piration  is  difcovered,  and  is  continued  throughout  our  lives,  as 
often  as  the  oppreffion  begins  to  recur.  Many  infants,  both  of 
the  human  creature,  and  of  quadrupeds,  ftruggle  for  a  minute 
after  they  are  born  before  they  begin  to  breathe,  (Haller.  Phyf. 
T.  8.  p.  400.  ib,  pt.  2  p.  i).  Mr.  Buffbn  thinks  the  a6tion  of  the 
dry  air  upon  the  nerves  of  fmell  of  new-born  animals,  by  pro- 
ducing an  endeavour  to  fneeze,  may  contribute  to  induce  this 
firft  infpiration,  and  that  the  rarefaction  of  the  air  by  the 
warmth  of  the  lungs  contributes  to  induce  expiration,  (Hid. 
Nat.  Tom.  4.  p.  174).  Which  latter  ir  may  effect  by  produ- 
cing a  difagreeable  fenfation  by  its  delay,  and  a  confequeut  ef- 
fort 


SECT.  XVI.  5.  i.          OF  INSTINCT.  105 

fort  to  relieve  it.     Many  children  fneeze  before  they  refpire,  but 
not  all,  as  far  as  I  have  obferved,  or  can  learn  from  others. 

At  length  by  the  direction  of  its  fenfe  of  fmell,  or  by  the  offi- 
cious care  of  its  mother,  the  young  animal  approaches  the  odo- 
riferous rill  of  its  future  nourimment,  already  experienced  to 
fwallow.  But  in  the  act  of  fwallowing,  it  is  neceflary  nearly 
to  clofe  the  mouth,  whether  the  creature  be  immerfed  in  the  fluid 
it  is  about  to  drink,  or  not ;  hence,  when  the  child  firft  attempts 
to  fuck,  it  does  not  flightly  comprefs  the  nipple  between  its  lips, 
and  fuck  as  an  adult  perfon  would  do,  by  abforbing  the  milk  ; 
but  it  takes  the  whole  nipple  into  its  mouth  for  this  purpofe, 
comprefTes  it  between  its  gums,  and  thus  repeatedly  chewing  (as 
it  were)  the  nipple,  prefTes  out  the  milk  ;  exactly  in  the  fame 
manner  as  it  is  drawn  from  the  teats  of  cows  by  the  hands  of 
the  milkmaid.  The  celebrated  Harvey  obferves,  that  the  foetus 
in  the  womb  mud  have  fucked  in  a  part  of  its  nourimment,  be- 
caufe  it  knows  how  to  fuck  the  minute  it  is  born,  as  any  one 
may  experience  by  putting  a  finger  between  its  lips,  and  becaufe 
in  a  few  days  it  forgets  this  art  of  fucking,  and  cannot  without 
fome  difficulty  again  acquire  it,  (Exercit.  de  Gener.  Anim.  48). 
The  fame  obfervation  is  made  by  Hi  ^pocrahjs 

A  little  further  experience  teaches  the  young  animal  to  fuck 
by  abforption,  as  well  as  by  compreffion  ;  that  is,  to  open  the 
cheft  as  in  the  beginning  of  refpiration,  and  thus  to  rarefy  the 
air  in  the  mouth,  that  the  preiTure  of  the  denfer  external  atmof- 
phere  may  contribute  to  force  out  the  milk. 

The  chick  yet  in  the  (hell  has  learnt  to  drink  by  fwallowing 
a  part  of  the  white  of  the  egg  for  its  food  ;  but  not  having  ex- 
perienced how  to  take  up  and  fwallow  folid  feeds,  or  grains,  is 
either  taught  by  the  felicitous  induftry  of  its  mother;  or  by 
many  repeated  attempts  is  enabled  at  length  to  diftinguUh  and 
to  fwaliow  this  kind  of  nutriment. 

And  puppies,  though  they  know  how  to  fuck  like  other  ani- 
mals from  their  previous  experience  in  fwallowing,  and  in  ref- 
piration ;  yet  are  they  Jong  in  acquiring  the  art  of  lapping  with 
their  tongues,  which  from  the  flaccidity  of  their  cheeks,  and 
length  of  their  mouths,  is  afterwards  a  more  convenient  way 
for  them  to  take  in  water. 

V.  The  fenies  of  fmell  and  tafte  in  many  other  animals 
greatly  excel  thofe  of  mankind,  for  in  civilized  fociety,  as  our 
victuals  are  generally  prepared  by  others,  and  are  adulterated 
with  fait,  fpice,  oil,  and  ernpyreuma,  we  do  not  hefitate  about 
eating  \vhatever  is  fet  before  us,  and  neglect  to  cultivate  thefe 
fenfes  :  whereas  other  animals  try  every  morfel  by  the  fmeil 
fore  they  take  it  into  their  mouths,  and  by  the  tafte  before  they 

VOL.  T.  P  fwallow 


iQO  OF  INSTINCT.  SECT.  XVI  6.  i. 

f wallow  it ;  and  are  led  not  only  each  to  his  proper  nouriftiment 
by  this  organ  of  fenfe,  but  it  alfo  at  a  maturer  age  directs  them 
in  the  gratification  of  their  appetite  of  love.  Which  may  be 
further  underftood  by  confidering  the  fympathies  of  thefe  parts 
defcribed  in  Clafs  IV.  2.  i.  7.  While  the  human  animal  is  di- 
re<fted  to  the  object  of  his  love  by  his  fenfe  of  beauty,  as  men- 
tioned in  No.  VI.  of  this  Section.  Thus  Virgil  Georg,  III.  25©. 

Nonne  vides,  ut  tota  tremor  pertentat  equorum 
Corpora,  fi  tantum  notas  odor  attulit  auras  ? 

Nonne  canis  nidum  veneris  nafutus  odore 
Quxrit,  et  erranti  trahitur  fublaiubere  lingaua  ? 
Rd'puit  at  guftum  cupidus,  labiifque  retracSlis 
Elevat  os,  trepidanfque  novis  impellitur  aeftris 
Inferit  et  vivum  felici  vomere  femen. — 
Quam  tenui  filo  cascos  adnecStit  amores 
Do«fla  Venus,  vitaeque  monet  renovare  favillam  ! 

ANON, 

The  following  curious  experiment  is  related  by  Galen.  "  On 
diflefting  a  goat  great  with  young,  I  found  a  briik  embryon,  and 
having  detached  it  from  the  matrix,  and  thatching  it  away  be- 
fore it  (aw  its  dam,  I  brought  it  into  a  certain  room,  where 
there  were  many  veflels,  fome  filled  with  wine,  others  with  oil, 
fome  with  honey,  others  with  milk,  or  fome  other  liquor  ;  and 
in  others  were  grains  and  fruits  ;  we  firft  obferved  the  young 
animal  get  upon  its  feet,  and  walk  ;  then  it  (hook  itfelf,  and  af- 
terwards fcratched  its  fide  with  one  of  its  feet  j  chen  we  faw  it 
fmelling  to  every  one  of  thefe  things,  that  were  fet  in  the  room  ; 
and  when  it  had  fmelt  to  them  all,  it  drank  up  the  milk."  L. 
6  de  locis.  cap.  6. 

Parturient  quadrupeds,  as  cats,  and  bitches,  and  fows,  are 
led  by  their  fenfe  of  fmell  to  eat  the  placenta  as  other  common 
food  ;  why  then  do  they  not  devour  their  whole  progeny,  as  is 
reprefented  in  an  ancient  emblem  of  TIME  ?  This  is  laid  fome- 
times  to  happen  in  the  unnatural  date  in  which  we  confine 
lows;  and  indeed  nature  would  feem  to  have  endangered  her 
offspring  in  this  nice  circumflance  !  but  at  this  time  the  ilimu- 
lus  of  the  milk  in  the  tumid  teats  of  the  mother  excites  her  to 
look  out  for,  and  to  defire  fome  unknown  circumftance  to  re- 
lieve her.  At  the  fame  time  the  fmell  of  the  milk  attracts  the 
exertions  of  the  young  animals  towards  its  fource,  and  thus  the 
delighted  mother  diicovers  a  new  appetite,  as  mentioned  in 
Seci.  XIV.  8.  and  her  little  progeny  are  led  to  receive  and  to 
communicate  pleafurc  by  this  moil  beautiful  contrivance. 

VI.  But  though  the  human  fpecies  in  fome  of  their  fenfa- 
:ions  are  much  inferiour  to  other  animals,  yet  the  accuracy  of  the 

fenfe 


SECT.  XVI.  6.  j.         OF  INSTINCT.  107 

fenfe  of  touch,  which  they  pofTefs  in  -ro  eminent  a  degree,  gives 
them  a  great  fuperioriry  of  underftanding  ;  as  is  well  obrerved 
by  the  ingenious  Mr.  BufFon.  The  extremities  of  other  animals 
terminate  in  horns,  and  hoofs,  and  claws,  very  unfit  for  the  fen- 
fation  of  touch  ;  whilft  the  human  hand  is  finely  adapted  to  en- 
eompafs  its  object:  with  this  organ  of  fenfe. 

The  elephant  is  indeed  endued  with  a  fine  fenfe  of  feeling  at 
the  extremity  of  his  probofcis,  and  hence  has  acquired  much 
more  accurate  ideas  of  touch  and  of  fight  than  mofl  othtr  crea- 
tures. The  two  following  inftances  of  the  fagacity  of  thefe  an- 
imals may  entertain  the  reader,  as  they  were  told  me  by  fome 
gentlemen  of  diflincl  obfervation,  and  undoubted  veracity,  who 
had  been  much  converfant  with  our  eaflern  fettlements.  Firft, 
the  elephants,  that  are  ufed  to  carry  the  baggage  of  our  armies, 
are  put  each  und^r  the  care  of  ore  of  the  natives  of  Indoflan,  and 
whilft  himfelf  and  his  wife  go  into  the  woods  to  collect  leaves 
and  branches  of  trees  for  his  food,  they  fix  him  to  the  ground 
by  a  length  of  chain,  and  frequently  leave  a  child  yet  unable  to 
walk,  under  his  proteclion  :  and  the  intelligent  animal  not  only 
defends  it,  but  as  it  creeps  about,  when  it  arrives  near  the  ex- 
tremity of  his  chain,  he  wraps  his  trunk  gently  round  its  body, 
tmd  brings  it  again  into  the  centre  of  his  circle.  Secondly,  the 
traitor  elephants  are  taught  to  walk  on  a  narrow  path  between 
two  pit-falls,  which  are  covered  with  turf,  and  then  to  go  into 
the  woods,  and  to  feduce  the  wild  elephants  to  come  that  way, 
who  fall  into  thefe  wells,  whilft  he  pafles  fafe  bee  ween  them  : 
and  it  is  univerfally  obferved,  that  thofe  wild  elephants  that  ef- 
cape  the  fnare,  purfue  the  traitor  wiih  the  utmoft  vehemence, 
and  if  they  can  overtake  him,  which  fometimes  happens,  they 
always  beat  him  to  death. 

The  monkey  has  a  hand  well  enough  adapted  for  the  fenfe  of 
touch,  which  contributes  to  his  great  facility  of  imitation  ;  but 
in  taking  objects  with  his  hands,  as  a  flick  or  an  apple,  he  puts 
Jiis  thumb  on  the  fame  fide  of  them  with  his  fingers,  inftead  of 
counteracting  the  preflure  of  his  fingers  with  it :  from  this  neg- 
Ie6l  he  is  much  flower  in  acquiring  the  figures  of  objecls,  as  he 
is  lefs  able  to  determine  the  diftances  or  diameters  of  their  parts, 
or  to  diftinguifh  their  vis  inertias  from  their  hardnefs.  Helve- 
tius  adds,  that  the  fhortnefs  of  his  life,  his  being  fugitive  be- 
fore mankind,  and  his  not  inhabiting  all  climates,  combine  to 
prevent  his  improvement.  (De  TEfprit.  T.  i.p.)  There  is 
however  at  this  time  an  old  monkey  fhewn  in  Exeter  Change, 
London,  who  having  lofl  his  teeth,  when  nuts  are  given  him, 
takes  a  flone  into  his  hand,  and  cracks  them  with  it  one  by  one  ; 
thus  ufmg  tools  to  effect;  his  purpofe  like  mankind. 

The 


io8  OF  INSTINCT.          SECT.  XVI.  6.  i. 

The  beaver  is  another  animal  that  makes  much  ufe  of  his 
hands,  and  if  we  may  credit  the  reports  of  travellers,  is  poflefled 
of  amazing  ingenuity.  This  however,  M  BurTon  affirms,  is  on- 
ly where  they  exift  in  large  numbers,  and  in  countries  thinly 
peopled  with  men  ;  while  in  France  in  their  folitary  (late  they 
{hew  no  uncommon  ingenuity. 

Indeed  all  the  quadrupeds,  that  have  collar-bones,  (claviculse) 
ufe  their  fore-limbs  in  fome  meafure  as  we  ufe  our  hands,  as  the 
cat,  fquirrel,  tyger,  bear  and  lion  ;  and  as  they  exercife  the  fenfe 
of  touch  more  univerfally  than  other  animals,  fo  are  they  more 
fagacious  in  watching  and  furprifmg  their  prey.  All  thofe  birds, 
that  ufe  their  claws  for  hands,  as  the  hawk,  parrot  and  cuckoo, 
appear  to  be  more  docile  and  intelligent  j  though  the  gregarious 
tribes  of  birds  have  more  acquired  knowledge, 

Now  as  the  images,  that  are  painted  on  the  retina  of  the  eye> 
are  no  other  than  figns,  which  recal  to  our  imaginations  the  ob- 
jects we  had  before  examined  by  the  organ  of  touch,  as  is  fully 
demonftrated  by  Dr.  Berkeley  in  his  treatife  on  vifion  ;  it  follows 
that  the  human  creature  has  greatly  more  accurate  and  diftinct 
fenfe  of  vifion  than  that  of  any  other  animal.  Whence  as  he 
advances  to  maturity  he  gradually  acquires  a  fenfe  of  female 
beauty,  which  at  this  time  dire&s  him  to  the  object  of  his  new 
paflion. 

Sentimental  love,  as  diflinguifhed  from  the  animal  paflion  of 
that  name,  with  which  it  is  frequently  accompanied,  confiils  in 
the  defire  or  fenfation  of  beholding,  embracing*  and  faluting  a 
beautiful  object. 

The  characteriftic  of  beauty  therefore  is  that  it  is  the  object 
of  love  :  and  though  many  other  objects  are  in  common  language 
called  beautiful,  yet  they  are  only  called  fo  metaphorically,  and 
ought  to  be  termed  agreeable.  A  Grecian  temple  may  give  us 
the  pleafurable  idea  of  fublimity,  a  Gothic  temple  may  give  us 
the  pleafurable  idea  of  variety,  and  a  modern  houfe  the  pleafur- 
able  idea  of  utility  5  mufic  and  poetry  may  infpire  cur  love  by 
aflbciation  of  ideas  ;  but  none  of  thefe,  except  metaphorically, 
can  be  termed  beautiful  ;  as  we  have  no  wiih  to  embrace  or  fa- 
lute  them. 

Our  perception  of  beauty  confifts  in  our  recognition  by  the 
fenfe  of  vifion  of  thofe  objects,  firft,  which  have  before  infpired 
our  love  by  the  pleafure,  which  they  have  afforded  to  many  of 
our  fenfes  :  as  to  our  fenfe  of  warmth,  of  touch,  of  fmell,  of 
tafte,  hunger  and  third  ;  and,  fecondly,  which  bear  any  analo- 
gy of  form  to  fuch  objects. 

When  the  babe,  foon  after  it  is  born  into  this  cold  world,  is 
applied  to  its  mother's  bofom  ;  its  fenfe  of  perceiving  warmth 

is 


SECT.  XVI.  7.  i.          OF  INSTINCT.  ioj> 

is  firft:  agreeably  afFefted  ;  next  its  fenfe  of  fmellis  delighted 
with  the  odour  of  her  milk  ;  then  its  tafle  is  gratified  by  the  fla- 
vour of  it  j  afterwards  the  appetites  of  hunger  and  of  third  afford 
pleafure  by  the  pofTeilion  of  their  objects,  and  by  the  fubfequent 
digeftion  of  the  aliment ;  and,  laiily,  the  fenfe  of  touch  is  de- 
lighted by  the  foftnefs  and  fmoothnefs  of  the  milky  fountain, 
the  fource  of  fuch  variety  of  happinefs. 

All  thefe  various  kinds  of  pleafure  at  length  become  afTociated 
with  the  form  of  the  mother's  breaft  ;  which  the  infant  embra- 
ces with  its  hands,  preffes  with  its  lips,  and  watches  with  its 
eyes  ;  and  thus  acquires  more  accurate  ideas  of  the  form  of  its 
mother's  bofom,  than  of  the  odour  and  flavour  or  warmth, 
which  it  perceives  by  its  other  fenfes.  And  hence  at  our  ma- 
turer  years,  when  any  object:  of  vifion  is  prefented  to  us,  which 
by  its  waving  or  fpiral  lines  bears  any  fimilitude  to  the  form  of 
the  female  bofom,  whether  it  be  found  in  a  landfcape  with  foft 
gradations  of  rifing  and  defcending  furface,  or  in  the  forms  of 
fome  antique  vafes,  or  in  other  works  of  the  pencil  or  the  chiflel, 
we  feel  a  general  glow  of  delight,  which  feems  to  influence  all 
our  lenfes  ;  and,  if  the  object  be  not  too  large,  we  experience  an 
attraction  to  embrace  it  with  our  arms,  and  to  falute  it  with  our 
lips,  as  we  did  in  our  early  infancy  the  bofom  of  our  mother. 
And  thus  we  find,  according  to  the  ingenious  idea  of  Hogarth, 
that  the  waving  lines  of  beauty  were  originally  taken  from  the 
temple  of  Venus. 

This  animal  attraction  is  love  ;  which  is  a  fenfation,  when 
the  object  is  prefenr ;  and  a  defire,  when  it  is  abfent  Which 
eonftitutes  the  pureil  fource  of  human  felicity,  the  cordial  drop 
in  the  otherwife  vapid  cup  of  life,  and  which  overpays  mankind 
for  the  care  and  labour,  which  are  attached  to  the  pre-eminence 
of  his  fituation  above  other  animals. 

It  (hould  have  been  obferved,  that  colour  as  well  as  form  fome- 
times  enters  into  our  idea  of  a  beautiful  object,  as  a  good  com- 
plexion for  inftance,  becaufe  a  fine  or  fair  colour  is  in  general 
a  fign  of  health,  and  conveys  to  us  an  idea  of  the  warmth  of  the 
object  ;  and  a  pale  countenance  on  the  contrary  gives  an  idea 
of  its  being  cold  to  the  touch. 

It  was  before  remarked,  that  young  animals  ufe  their  lips  to 
diftinguifli  the  forms  of  things,  as  well  as  their  fingers,  and 
hence  we  learn  the  origin  of  our  inclination  to  falute  beautiful 
objects  with  our  lips.  For  a  definition  of  Grace,  fee  Clais  III. 
i.  2.  4. 

VII.  There  are  two  ways  by  which  we  become  acquainted 
with  the  paflions  of  others  :  firft,  by  having  obferved  the  effects 
of  them,  as  of  fear  or  anger,  on  our  <->vvn  bodies,  we  know  at 

fight 


MO  OF  INSTINCT.        SECT. XVI.  8.  i 

fight  when  others  are  under  the  influence  ofthefe  affeftions. 
So  when  two  cocks  are  preparing  to  fight,  each  feels  the  feath- 
ers rife  round  his  own  neck,  and  knows  from  the  fame  fjgn  the 
diipofition  of  his  adverfary  :  and  children  Jong- before  they  cart 
fpcak,  or  underfland  the  language  of  their  parents,  may  be 
frightened  by  an  angry  countenance,  or  foothed  by  fmiles  and 
blandifhments. 

Secondly,  when  we  put  ourfelves  into  the  attitude  that  any 
paffion  naturally  occafions,  we  foon  in  fome  degree  acquire  that 
paflion  ;  hence  when  thofe  that  fcold  indulge  themfelves  in  loud 
oaths,  and  violent  actions  of  the  arms,  they  increafe  their  anger 
by  the  mode  of  exprefiing  themfelves  :  and  on  the  contrary  the 
counterfeited  fmile  of  pleafure  in  difagreeable  company  foon 
brings  along  with  it  a  portion  of  the  reality,  as  is  well  illuflrated 
by  Mr.  Burke,  (Eflay  on  the  Sublime  and  Beautiful.) 

This  latter  method  of  entering  into  the  paffions  of  others  is 
rendered  of  every  extenfive  ufeby  the  pleafure  we  take  in  imita- 
tion, which  is  every  day  prefented  before  our  eyes,  in  the  actions 
of  children,  and  indeed  in  all  the  cuftoms  and  fafliions  of  the 
world.  From  vhis  our  aptitude  to  imitation,  arifes  what  is  gen- 
erally underllood  by  the  word  fympathy,  fo  well  explained  by  Dr. 
Smith  of  Glafgow  Thus  the  appearance  of  a  cheerful  coun- 
tenance gives  us  pleafure,  and  of  a  melancholy  one  makes  us 
forrowful  Yawning  and  fometimes  vomiting  are  thus  propa- 
gated by  fympathy,  and  fome  people  of  delicate  fibres,  at  the 
prefence  of  a  fpe^lacie  of  mifery,  have  felt  pain  in  the  fame 
farts  of  their  own  bodies,  that  were  difeafed  or  mangled  in  the 
other.  Amongil  the  writers  of  antiquity  Ariftotle  thought  this 
aptitude  to  imitation  an  eflential  property  of  the  human  fpecies, 
and  calls  man  an  imitative  animal.  To  gaov  pipamvov. 

Thefe  then  are  the  natural  figns  by  which  we  underftand  each 
other,  and  on  this  ilender  bafis  is  built  all  human  language.  For 
without  fome  natural  figns,  no  artificial  ones  could  have  been 
invented  or  underllood,  as  is  very  ingenioufly  obferved  by  Dr. 
Reid,  (Inquiry  into  the  Human  Mind.) 

VIII.  The  origin  of  this  univerfal  language  is  a  fubjecl:  of  the 
highetf  curiofity,  the  knowledge  of  which  has  always  been 
thought  utterly  inacceffible.  A  part  of  which  we  fliall  however 
here  attempt. 

Light,  found,  and  odours,  are  unknown  to  the  foetus  in  the 
womb,  which,  except  the  few  fenfations  and  motions  already 
mentioned,  fleeps  away  its  time  infenfible  of  the  bufy  world. 
But  the  moment  it  arrives  into  day,  it  begins  to  experience 
many  vivic  ains  and  pleafures  ;  thefe  are  at  the  fame  time  at- 
.tended  with  certain  mufcular  motions,  and  from  this  their 

early, 


.  XVI.  8.  i.        OF  INSTINCT.  1 1  i 

early,  and   individual  aflbciation,  they  acquire  habits  of  occur- 
ring together,  that  are  afterwards  indifiblubie. 

1.  Of  Fear. 

As  foon  as  the  young  animal  is  born,  the  firft  important  fen* 
fations,  that  occur  to  him,  are  occafioned  by  the  oppreffion  about 
his  precordia  for  want  of  refpiration,  and  by  his  fudden  tranfi- 
tion  from  ninety-eight  degrees  of  heat  into  fo  cold  a  climate.— 
He  trembles,  that  is,  he  exerts  alternately  all  the  mufcles  of  his 
body,  to  enfranchife  himfelf  from  the  oppreflion  about  his  bofom, 
and  begins  to  breathe  with  frequent  and  fhort  refpirations  ;  at 
the  fame  time  the  cold  contracts  his  red  ikin,  gradually  turning 
it  pale  ;  the  contents  of  the  bladder  and  of  the  bowels  are  evac- 
uated :  and  from  the  experience  of  theie  firft  difagreeable  fenfa- 
tions  the  pailion  of  fear  is  excited,  which  is  no  other  than  the 
expectation  of  difagreeable  fenfations.  This  early  aflbciation  of 
motions  and  fenfations  perfifts  throughout  life  ;  the  pailion  of 
fear  produces  a  cold  and  pale  (kin,  with  tremblings,  quick  refpi- 
ration,  and  an  evacuation  of  the  bladder  and  bowels,  and  thus 
conititutes  the  natural  or  uriiverfal  language  of  this  pailion. 

On  obferving  a  canary  bird  this  morning,  January  28,  1772, 
at  the  houfe  of  Mr.  Harvey,  near  Tutbury,  in  Derbyfhire,  I  was 
told  it  always  fainted  away,  when  its  cage  was  cleaned,  and  de- 
fired  to  fee  the  experiment.  The  cage  being  taken  from  the 
ceiling,  and  its  bottom  drawn  out,  the  bird  began  to  tremble, 
and  turned  quite  white  about  the  root  of  his  bill :  he  then  open- 
ed his  mouth  as  if  for  breath,  and  refpired  quick,  flood 
flraighter  up  on  his  perch,  hung  his  wings,  fpread  his  tail,  clofed 
his  eyes,  and  appeared  quite  ftifFand  cataleptic  for  near  half  an 
hour,  and  at  length  with  much  trembling  and  deep  refpirations 
came  gradually  to  himfelf. 

2.  Of  Grief. 

That  the  internal  membrane  of  the  noftrils  may  be  kept  al- 
ways moift,  for  the  better  perception  of  odours,  there  are  tw$ 
canals,  that  conduct  the  tears  after  they  have  done  their  office 
in  moiftening  and  cleaning  the  ball  of  the  eye  info  a  fack,  whicfe 
is  called  the  lacrymal  fack  ;  and  from  which  there  is  a  duft, 
that  opens  into  the  noftrils :  the  aperture  of  this  du£l  is  formed 
of  exquiilte  fenfibility,  and  when  it  is  ftimdated  by  odorous 
particles,  or  by  the  drynefs  or  coldnefs  of  the  air,  the  fack  con* 
tracls  itfelf,  and  pours  more  of  its  contained  moifture  on  the  or- 
gan of  laielL  By  this  contrivance  the  organ  is  rendered  more 

fit 


m  OF  INSTINCT.        SECT.  XVI.  8.  2, 

fit  for  perceiving  fuch  odours,  and  is  preferved  from  being  in- 
jured by  thofe  that  are  more  ftrong  or  corrofive.  M my  other 
receptacles  of  peculiar  fluids  difgorge  their  contents,  when  the 
ends  of  their  duels  are  ftimulated  ;  as  the  gall  bladder,  when  the 
contents  of  the  duodenum  ftimulate  the  extremity  of  the  com- 
mon bile  duel  ;  and  the  falivary  glands,  when  the  termination 
of  their  duels  in  the  mouth  are  excited  by  the  Itimulus  of  the 
food  we  mafticate.  Atque  veficulse  feminales  fuum  exprimunt 
fluidum  glande  penis  fricata 

The  coldnefs  and  drynefs  of  the  atmofphere,  compared  w?th 
the  warmth  and  moilture,  which  the  new-born  infant  had  jull 
before  experienced,  difagreeably  affect  the  aperture  of  this  lav-ry- 
inal  lack  :  the  tears,  that  are  contained  in  this  fack,  are  poured 
into  the  noftrils,  and  a  further  fupply  is  fecreted  by  the  laery- 
mal  glands,  and  diffufcd  upon  the  eye-balls  ;  as  is  very  vifible  in 
the  eyes  and  noflrils  of  children  foon  after  their  nativity.  The 
fame  happens  to  us  at  our  maturer  age,  for  in  fevere  frofty 
weather,  Snivelling  and  tears  are  produced  by  the  coldnefs  and 
drynefs  of  the  air. 

But  the  lacrymal  glands,  which  feparate  the  tears  from  the 
blood,  are  fituated  on  the  upper  external  part  of  the  globes  of 
each  eye  $  and,  when  a  greater  quantity  of  tears  are  wanted,  we 
contract  the  forehead,  and  bring  down  the  eye-brows,  and  ufe 
many  other  diftortions  of  the  face,  to  comprefs  thefe  glands. 

Now  as  the  fuffocating  fenfation,  that  produces  reipiration,  is 
removed  almoft  as  foon  as  perceived,  and  does  not  recur  again  : 
this  difagreeable  irritation  of  the  lacrymal  duels,  as  it  muft  fre- 
quently recur,  till  the  tender  organ  becomes  ufed  to  variety  of 
odours,  is  one  of  the  firft  pains  that  is  repeatedly  attended  to  : 
and  hence  throughout  our  infancy,  and  in  many  people  through- 
out their  lives,  all  difagreeable  fenfations  are  attended  with  fniv- 
elllingat  the  nofe,  a  profufion  of  tears,  and  fome  peculiar  diftor- 
tions of  countenance:  according  to  the  laws  of  early  afTociation 
before  mentioned,  which  conftitutes  the  natural  or  univerfal 
language  of  grief 

You  may  aflure  yourfelf  of  the  truth  of  this  obfervation,  if 
you  will  attend  to  what  pafles,  when  you  read  a  diiirefsful  tale 
alone  ,  before  the  tears  overflow  your  eyes,  you  will  invariably 
feel  a  titillation  at  that  extremity  of  the  lacrymal  duel,  which 
terminates  in  the  noftril,  then  the  compreflion  of  the  eyes  fuc- 
ceeds,  and  the  profufion  of  tears. 

Linnseus  afferts,  that  the  female  bear  fheds  tears  in  grief  j  the 
fame  has  been  faid  of  the  hind,  and  fome  other  animals. 

3-  Of 


SECT.  XVI.  8. 3.  OF  INSTINCT.  1 13 

3.  Of  Tender  Pleasure. 

The  firft  moft  lively  impreflion  of  pleafure,  that  the  infant 
enjoys  after  its  nativity,  is  excited  by  the  odour  of  its  mother's 
milk.  The  organ  of  fmell  is  irritated  by  this  perfume,  and  the 
lacrymal  fack  empties  itfelfinto  the  noftrils,  as  before  explained, 
and  an  increafe  of  tears  is  poured  into  the  eyes.  Any  one  may 
obferve  this,  when  very  young  infants  are  about  to  fuck  ;  for  at 
thofe  early  periods  of  life,  the  fenfation  affe&s  the  organ  of 
fmeil,  much  more  powerfully,  than  after  the  repeated  habit  of 
fmelling  has  inured  it  to  odours  of  common  itrength :  and  in. 
our  adult  years,  the  ftronger  fmells,  though  they  are  at  the  fame 
time  agreeable  to  us,  as  of  volatile  fpirits,  continue  to  produce 
an  increafed  fccretion  of  tears. 

The  pleafing  fenfation  of  fmell  is  followed  by  the  early  af- 
fection of  the  infant  to  the  mother  that  fuckles  it,  and  hence  the 
tender  feelings  of  gratitude  and  love,  as  well  as  of  hopelefs  grief, 
are  ever  after  joined  with  the  titillation  of  the  extremity  of  the 
lacrymal  duds,  and  a  profufion  of  tears. 

Nor  is  it  fingular,  that  the  lacrymal  fack  (hould  be  influenced 
by  pleafing  ideas,  as  the  fight  of  agreeable  food  produces  the 
fame  effect  on  the  falivary  glands.  Ac  dum  vidimus  in  fom- 
niis  lafcivse  puelhe  fimulacrum  tenditur  penis. 

Lambs  make  or  wriggle  their  tails,  at  the  time  when  they  firft 
fuck,  to  get  free  of  the  hard  excrement,  which  had  been  long 
lodged  in  their  boweis.  Hence  this  becomes  afterwards  a  mark 
of  pleafure  in  them,  and  in  dogs  and  other  tailed  animals.  But 
cats  gently  extend  and  contract  their  paws  when  they  are  pleaf- 
ed,  and  purr  by  drawing  in  their  breath,  both  which  refemble 
their  manner  of  fucking,  and  thus  become  their  language  of 
pleafure,  for  thefe  animals  having  collar-bones,  ufe  their  paw$ 
like  hands  when  they  fuck,  which  dogs  and  (heep  do  not* 

4.  Of  Serene  Pleafure. 

In  the  action  of  fucking,  the  lips  cf  the  infant  are  clofed 
around  the  nipple  of  his  mother,  till  he  has  filled  his  ftomach, 
and  the  pleafure  occadoned  by  the  ftimulus  of  this  grateful  food 
fucceeds.  Then  the  fphincter  of  the  mouth,  fatigued  by  the 
continued  action  of  tucking,  is  relaxed  ;  and  the  antagonift  muf- 
cles  of  the  face  gently  acting,  produce  the  fmile  of  pleafure  : 
as  cannot  but  be  feen  by  all  who  are  converfant  with  children 

Hence  this  fmile  during  our  lives  is  aflbciated  with  gentle 
pleafure ;  it  is  vifible  in  kittens,  and  puppies,  when  they  are 
played  with,  and  tickled  ;  but  more  particularly  marks  the  hu 

VOL.  I.  O 


1 14  OF  INSTINCT.  SECT.  XVI.  3. 5, 

man  features.  For  in  children  this  expreflion  of  pleafure  is 
much  encouraged,  by  their  imitation  of  their  parents,  or  friends  ; 
who  generally  addrefs  them  with  a  fmiling  countenance :  and 
hence  fome  nations  are  more  remarkable  for  the  gaiety,  and  oth> 
ers  for  the  gravity  of  their  looks. 

5.  Of  Anger. 

The  actions  that  conftitute  the  mode  of  fighting,  are  the  im- 
mediate language  of  anger  in  all  animals  ;  and  a  preparation 
for  thefe  actions  is  the  natural  language  of  threatening.  Hence 
the  human  creature  clenches  his  fift,  and  fternly  furveys  his  ad- 
verfary,  as  if  meditating  where  to  make  the  attack  ;  the  ram, 
and  the  bull,  draws  himfelf  fome  fteps  backwards,  and  levels  his 
horns  ;  and  the  horfe,  as  he  mod  frequently  fights  by  ftriking 
with  his  hinder  feet,  turns  his  heels  to  his  foe,  and  bends  back 
his  ears,  to  liften  out  the  place  of  his  adverfary,  that  the  threat- 
ened blow  may  not  be  ineffectual. 

6.   Of  Attention. 

The  eye  takes  in  at  once  but  half  our  horizon,  and  that  only 
in  the  day,  and  our  fmell  informs  us  of  no  very  diftant  objects, 
hence  we  confide  principally  in  the  organ  of  hearing  to  apprize 
us  of  danger  ;  when  we  hear  any  the  fmalleft  found,  that  we 
cannot  immediately  account  for,  our  fears  are  alarmed,  we  fuf- 
pend  our  fteps,  hold  every  mufcle  (till,  open  our  mouths  a  little, 
erect  our  ears,  and  liften  to  gain  further  information  :  and  this 
by  habit  becomes  the  general  language  of  attention  to  objects  of 
fight  as  well  as  of  hearing  ;  and  even  to  the  fucceflive  trains  of 
our  ideas. 

The  natural  language  of  violent  pain,  which  is  exprefTed  by 
writhing  the  body,  grinning  and  fcreaming  ;  and  that  of  tumul- 
tuous pleafure,  exprefled  in  loud  laughter ;  belong  to  Section 
XXXIV.  on  Difeafes  from  Volition. 

IX.  It  muft  have  already  appeared  to  the  reader,  that  all  other 
animals  as  well  as  men,  are  poflefied  of  this  natural  language  of 
the  pafllons,  exprefled  in  figns  or  tones ;  and  we  fhall  endeav- 
our to  evince,  that  thofe  animals,  which  have  preferved  them- 
felves  from  being  enilaved  by  mankind,  and  are  aflbciated  in 
flocks,  are  alfo  pofTefled  of  fome  artificial  language,  and  of  fome 
traditional  knowledge. 

The  mother  turkey,  when  (lie  eyes  a  kite  hovering  high  in  air, 
has  either  feen  her  own  parents  thrown  into  fear  at  his  pref- 
pnce,  or  has  by  obfervation  been  acquainted  with  his  dangerous 

defigns 


SECT.  XVI.  9.  i .          OF  INSTINCT.  2 ,  $ 

defigns  upon  her  young.     She  becomes  agitated  with  fear,  and 
ufes  the  natural  language  of  that  paflion,  her  young  ones  catch" 
the  fear  by  imitation,  and  in  an  initant  conceal  themfelves  in 
the  grafs. 

At  the  fame  time  that  (he  (hews  her  fears  by  her  gefture  and 
deportment,  (he  ufes  a  certain  exclamation,  Koe-ut,  Koe-ut,  and 
the  young  ones  afterwards  know,  when  they  hear  this  note, 
though  they  do  not  fee  their  dam,  that  the  prefence  of  their  ad- 
verfary  is  announced,  and  hide  themfelves  as  before. 

The  wild  tribes  of  birds  have  very  frequent  opportunities  of 
knowing  their  enemies,  by  obferving  the  deflruclion  they  make 
among  their  progeny,  of  which  every  year  but  a  finall  part 
efcapes  to  maturity;  but  to  our  domeflic  birds  thefe  opportuni- 
ties fo  rarely  occur,  that  their  knowledge  of  their  diftant  ene- 
mies muft  frequently  be  delivered  by  tradition  in  the  manner 
above  explained,  through  many  generations. 

This  note  of  danger,  as  well  as  the  other  notes  of  the  mother- 
turkey,  when  fhe  calls  her  flock  to  their  food,  or  to  fleep  under 
her  wings,  appears  to  be  an  artificial  language,  both  as  exprefled 
by  the  mother,  and  as  underftood  by  the  progeny.  Fot  a  hen 
reaches  this  language  with  equal  eafe  to  the  ducklings,  (lie  has 
hatched  from  fuppofititious  eggs,  and  educates  as  her  own  off- 
fpring :  and  the  wagtails,  or  hedge-fparrows,  learn  it  from  the 
young  cuckoo  their  fofler  nurfling,  and  fupply  him  with  food 
long  after  he  can  fly  about,  whenever  they  hear  his  cuckooing, 
which  Linnaeus  tells  us,  is  his  call  of  hunger,  (Syft.  Nat.)  And 
all  our  domeflic  animals  are  readily  taught  to  come  to  us  for 
food,  when  we  ufe  one  tone  of  voice,  and  to  fly  from  our  anger, 
when  we  ufe  another. 

Rabbits,  as  they  cannot  eafily  articulate  founds,  and  are  form- 
ed into  focieties,  that  live  under  ground,  have  a  very  different 
method  of  giving  alarm.  When  danger  is  threatened,  they 
thump  en  the  ground,  with  one  of  their  hinder  feet,  and  produce 
a  found,  that  can  be  heard  a  great  way  by  animals  near  the  fur- 
face  of  the  earth,  which  would  feem  to  be  an  artificial  fign  both 
from  its  fingularity  and  its  aptnefs  to  the  fituation  of  the  animal. 

The  rabbits  on  the  ifland  of  Sor,  near  Senegal,  have  white 
flefh,  and  are  well  tafted,  but  do  not  burrow  in  the  earth,  fo 
that  we  may  fufpecl:  their  digging  themfelves  houfes  in  this  cold 
climate  is  an  acquired  art,  as  well  as  their  note  of  alarm.  ( Adan- 
fon's  Voyage  to  Senegal). 

The  barking  of  dogs  is  another  curious  note  of  alarm,  and 
would  feem  to  be  an  acquired  language,  rather  than  a  natural 
fjgn  :  for  cc  in  the  ifland  of  Juan  Fernandes,  the  dogs  did  not 
attempt  to  bark,  till  fome  European  dogs  were  put  among  them, 

and 


i  j  6  OF  INSTINCT.          SECT.  XVI.  i  o.  r . 

and  then  they  gradually  began  to  imitate  them,  but  in  a  ftrange 
manner  at  firft,  as  if  they  were  learning  a  thing  that  was  not 
natural  to  them,"  (Voyage  to  South  America  by  Don  G.  Juan, 
and  Don  Ant.  de  Ulloa.  B.  2.  c.  4). 

Linnaeus  alfo  obferves,  that  the  dogs  of  South  America  do  not 
bark  at  ftrangers,  (Syft.  Nat. )  And  the  European  dogs,  that 
have  been  carried  to  Guinea,  are  faid  in  three  or  four  genera- 
tions to  ceafe  to  bark,  and  only  howl,  like  the  dogs  that  are  na- 
tives of  thatcoaft,  (World  Difplayed,  Vol.  XVII.  p.  26.) 

A  circumflance  not  difiimilar  to  this,  and  equally  curious,  is 
mentioned  by  Kircherus  de  Mufurgia,  in  his  Chapter  de  Luf~ 
ciniis.  "  That  the  young  nightingales  that  are  hatched  under 
other  birds,  never  fing  till  they  are  inftru&ed  by  the  company  of 
other  nightingales."  And  Jonfton  affirms,  that  the  nightingales 
that  vifit  Scotland,  have  not  the  fame  harmony  as  thofe  of  Italy, 
(Pennant's  Zoology,  oftavo,  p.  255) ;  which  would  lead  us  to 
fufpecl:  that  the  finging  of  birds,  like  human  mufic,  is  an  arti- 
ficial language,  rather  than  a  natural  exprefiion  of  paflion. 

X.  Our  mufic  like  our  language,  is  perhaps  entirely  conftitui 
ted  of  artificial  tones,  which  by  habit  fuggeft  certain  agreeable 
paflions.  For  the  fame  combination  of  notes  and  tones  do  not 
excite  devotion,  love,  or  poetic  melancholy  in  a  native  of  Indof- 
tan  and  of  Europe.  And  "  the  Highlander  has  the  fame  war- 
like ideas  annexed  to  the  found  of  a  bagpipe  (an  inftrument 
which  an  Englifhman  derides),  as  the  Englimman  has  to  that  of 
a  trumpet  or  fife."  (Dr.  Brown's  Union  of  Poetry  and  Mufic, 
p.  58.)  So  "  the  mufic  of  the  Turks  is  very  different  from  the 
Italian,  and  the  people  of  Fez  and  Morocco  have  again  a  differ- 
ent kind,  which  to  us  appears  very  rough  and  horrid,  but  is 
highly  pleafing  to  them,"  (L'Arte  Armonica  a  Giorgio  Antoni- 
otto).  Hence  we  fee  why  the  Italian  opera  does  not  dalightan 
untutored  Englifhman  ;  and  why  thofe  who  are  unaccuftomed 
to  mufic,  are  more  pleafed  with  a  tune  the  fecond  or  third  time 
they  hear  it  than  the  firft.  For  then  the  fame  melodious  train 
of  founds  excites  the  melancholy,  they  had  learned  from  the 
fong ;  or  the  fame  vivid  combination  of  them  recals  all  the 
mirthful  ideas  of  the  dance  and  company. 

Even  the  founds,  that  were  once  difagreeable  to  us,  may  by 
habit  be  affociated  with  other  ideas,  fo  as  to  become  agreeable. 
Father  Lafitau,  in  his  account  of  the  Iroquois,  fays  the  mufic 
and  dance  of  thofe  Americans  have  fomething  in  them  extremely 
barbarous,  which  at  firft  difgufts.  We  grow  reconciled  to  them 
by  degrees,  and  in  the  end  partake  of  them  with  pleafure :  the 
favages  themfelves  are  fond  of  them  to  diftraftion."  (Mceurs 
des  Savages,  Tom,  ii.) 

There 


SECT.  XVI.  10.  i.        OF  INSTINCT,  117 

There  are  indeed  -\  few  founds,  that  \ve  very  generally  aiTo- 
ciate  with  agreeable  ideas,  as  the  whittling  of  birds,  or  purring 
of  animals,  that  are  delighted  ;  and  fome  others,  that  we  as  gen- 
erally aiToci ate  with  difagreeable  ideas,  as  the  cries  of  animals  in 
pain,  the  hifs  of  Tome  of  them  in  anger,  and  the  midnight  howl 
of  beads  of  prey.  Yet  we  receive  no  terrible  or  fublime  ideas 
from  the  lowing  of  a  cow,  or  the  braying  of  an  afs.  Which 
evinces  that  thefe  emotions  are  owing  to  previous  aflbciations. 
So  if  the  rumbling  of  a  carriage  in  the  flreet  be  for  a  moment 
miftaken  for  thunder,  we  receive  a  fublime  fenfation,  which 
ceafes  as  foon  as  we  know  it  is  the  noife  of  a  coach  and  fix. 

There  are  other  difagreeable  founds,  that  are  faid  to  fet  the 
teeth  on  edge  ;  which,  as  they  have  always  been  thought  a  ne- 
ceffary  effecl:  of  certain  difcordant  notes,  become  a  proper  fub- 
ject  of  our  inquiry.  Every  one  in  his  childhood  has  repeatedly 
bit  a  part  of  the  glafs  or  earthen  veffel,  in  which  his  food  has 
been  given  him,  and  has  thence  had  a  very  difagreeable  fenfa- 
tion in  the  teeth,  which  fenfation  was  defigned  by  nature  to 
prevent  us  from  exerting  them  on  objects  harder  than  themfelves, 
The  jarring  found  produced  between  the  cup  and  the  teeth  is 
always  attendant  on  this  difagreeable  fenfation  :  and  ever  after 
when  fuch  a  found  is  accidentally  produced  by  the  conflict  of 
two  hard  bodies,  we  feel  by  aflbciation  of  ideas  the  concomitant 
difagreeable  fenfation  in  our  teeth. 

Others  have  in  their  infancy  frequently  held  the  corner  of  a 
filk  handkerchief  in  their  mouth,  or  the  end  of  the  velvet  cape 
of  their  coat,  whilft  their  companions  in  play  have  plucked  it 
from  them,  and  have  given  another  difagreeable  fenfation  to 
their  teeth,  which  has  afterwards  recurred  on  touching  thofe 
materials.  And  the  fight  of  a  knife  drawn  along  a  china  plate, 
though  no  found  is  excited  by  it,  and  even  the  imagination  of 
fuch  a  knife  and  plate  fo  fcraped  together,  I  know  by  repeated 
experience  will  produce  the  fame  difagreeable  fenfation  of  the 
teeth. 

Thefe  circumftances  indifputably  prove,  that  this  fenfation  of 
the  tooth-edge  is  owing  to  aflbciated  ideas  ;  as  it  is  equally  ex- 
citable by  fight,  touch,  hearing,  or  imagination. 

In  refpedl  to  the  artificial  proportions  of  found  excited  by  mu- 
fkal  inftruments,  thofe,  who  have  early  in  life  aflbciated  them 
with  agreeable  ideas,  and  have  nicely  attended  to  diftinguifh 
them  from  each  other,  are  faid  to  have  a  good  ear,  in  that  coun- 
try where  fuch  proportions  are  in  fafhion  :  and  not  from  any 
fuperior  perfe&ion  in  the  organ  of  hearing,  or  any  inftin&ive 
fympathy  between  certain  founds  and  paflions. 

I  have  obferved  a  child  to  be  exquifitely  delighted  with  mufic, 

and 


n8  OF  INSTINCT.        SECT.  XVI.  n.  r. 

and  who  could  with  great  facility  learn  to  fing  any  tune  that  he 
heard  diftindtly,  and  yet  whofe  organ  of  hearing  was  fo  imper- 
fect, that  it  was  neceffary  to  fpeak  louder  to  him  in  common 
converfation  than  to  others. 

Our  mufic,  like  our  architecture,  feems  to  have  no  founda- 
tion in  nature,  they  are  both  arts  purely  of  human  creation,  as 
they  imitate  nothing.  And  the  profefTors  of  them  have  only 
clafled  thofe  circumitances,  that  are  moft  agreeable  to  the  acci- 
dental  tafie  of  their  age,  or  country  •,  and  have  called  it  Propor- 
tion. But  this  proportion  muft  always  fluctuate,  as  it  reflson 
the  caprices,  that  are  introduced  into  our  minds,  by  our  various 
modes  of  education.  And  thefe  fluftuations  of  tafte  mud  be- 
come more  frequent  in  the  prefent  age,  where  mankind  have 
enfranchifed  themfelves  from  the  blind  obedience  of  the  rules  of 
antiquity  in  perhaps  every  fcience,  but  that  of  architecture.  See 
Sea.  XII.  7.  3. 

XL  There  are  many  articles  of  knowledge,  which  the  ani- 
mals in  cultivated  countries  feem  to  learn  very  early  in  their 
lives,  either  from  each  other,  or  from  experience,  or  obferva- 
tion  :  one  of  the  moft  general  of  diefe  is  to  avoid  mankind. 
There  is  fo  great  a  refemblance  in  the  natural  language  of  the 
paffionsof  all  animals,  that  we  generally  know,  when  they  are 
in  a  pacific,  or  in  a  malevolent  humour  ;  they  have  the  fame 
knowledge  of  us  ;  and  hence  we  can  fcold  them  from  us  by 
fome  tones  and  geftures,  and  could  poflibly  attract  them  to  us 
by  others,  if  they  were  not  already  apprized  of  our  general  ma- 
levolence towards  them.  Mr.  Gmelin,  Profeflbr  at  Peterfburg, 
affures  us,  that  in  his  journey  into  Siberia,  undertaken  by  order 
of  the  Emprefs  of  Ruflia,  he  faw  foxes  that  expreffed  no  fear  of 
himfelf  or  companions,  but  permitted  him  to  come  quite  near 
them,  having  never  feen  the  human  creature  before.  And  Mr. 
Bougainville  relates,  that  at  his  arrival  at  the  Maloune,  or  Falk- 
land's Iflands,  which  were  not  inhabited  by  men,  all  the  ani- 
mals came  about  himfelf  and  his  people  ;  the  fowls  fettling  up- 
on their  heads  and  moulders,  and  the  quadrupeds  running  about 
their  feet.  From  the  difficulty  of  acquiring  the  confidence  of 
old  animals,  and  the  eafe  of  taming  young  ones,  it  appears 
that  the  fear,  they  all  conceive  at  the  fight  of  mankind,  is  an  ac- 
quired article  of  knowledge. 

This  knowledge  is  more  nicely  underflood  by  rooks,  who  are 
formed  into  focieties,  and  build,  as  it  were,  cities  over  our  heads ; 
they  evidently  diftinguifh,  that  the  danger  is  greater  when  a 
man  is  armed  with  a  gun.  Every  one  has  feen  this,  who  in 
the  fpring  of  the  year  has  walked  under  a  rookery  with  a  gun  in 
his  hand  :  the  inhabitants  of  the  trees  rife  on  their  wings,  and 

fere  am 


OECT.  XVI.  1 1.  i.         OF  INSTINCT.  1 19 

fcream  to  the  unfledged  young  to  fhrink  into  their  nefts  from 
the  fight  of  the  enemy.  The  vulgar  obferving  this  circum- 
ftance  fo  uniformly  to  occur,  aflert  that  rooks  can  fmell  gun- 
powder. 

The  fieldfares,  (turdus  pilaris)  which  breed  in  Norway,  and 
come  hither  in  the  cold  feafon  for  our  winter  berries;  as  they 
are  aflbciated  in  flocks,  and  are  in  a  foreign  country,  have  evi- 
dent marks  of  keeping  a  kind  of  watch,  to  remark  and  announce 
the  appearance  of  danger.  On  approaching  a  tree,  that  is  cov- 
ered with  them,  they  continue  fearlefs  till  one  at  the  extremity 
of  the  bufh  rifing  on  his  wings  gives  a  loud  and  peculiar  note  of 
alarm,  when  they  all  immediately  fly,  except  one  other,  who 
continues  till  you  approach  ftill  nearer,  to  certify  as  it  were  the 
reality  of  the  danger,  and  then  he  alfo  flies  off  repeating  the  note 
of  alarm. 

And  in  the  woods  about  Senegal  there  is  a  bird  called  uett- 
uett  by  the  negroes,  and  fquallers  by  the  French,  which,  asfooa 
as  they  fee  a  man,  fet  up  a  loud  fcream,  and  keep  flying  round 
him,  as  if  their  intent  was  to  warn  other  birds,  which  upon 
hearing  the  cry  immediately  take  wing.  Thefe  birds  are  the 
bane  of  fportfmen,  and  frequently  put  me  into  a  paflion,  and 
ob1  ged  me  to  fhoot  them,  (Adanfon's  Voyage  to  Senegal,  78.) 
For  the  fame  intent  the  lefler  birds  of  our  climate  feem  to  fly 
after  a  hawk,  cuckoo,  or  owl,  and  fcream  to  prevent  their  com- 
panions from  being  furprifed  by  the  general  enemies  of  them- 
ielves,  or  of  their  eggs  and  progeny. 

But  the  lapwing,  (charadrius  pluvialis  Lin.)  when  her  un- 
fledged offspring  run  about  the  marfhes,  where  they  were  hatch- 
ed, not  only  gives  the  note  of  alarm  at  the  approach  of  men  or 
dogs,  that  her  young  may  conceal  themfelves  ;  but  flying  and 
fcreaming  near  the  adverfary,  (he  appears  more  folicitous  and 
impatient,  as  he  recedes  from  her  family,  and  thus  endeavours 
to  miflead  him,  and  frequently  fucceeds  in  her  defign.  Thefc 
laft  inflances  are  fo  appofite  to  the  fituation,  rather  than  to  the 
natures  of  the  creatures,  that  ufe  them  ;  and  are  fo  fimilar  to 
the  actions  of  men  in  the  fame  circumftances,  that  we  cannot 
but  believe,  that  they  proceed  from  a  fimilar  principle. 

Mifs  M.  E.  Jackfon  acquainted  me,  that  me  witneffrd  this 
autumn  an  agreeable  inftance  of  fagacity  in  a  little  bird,  which 
fcemed  to  ufe  the  means  to  obtain  an  end  ;  the  bird  repeatedly 
hopped  upon  a  poppy-ftem,  and  (hook  the  head  with  its  bill,  till 
many  feeds  were  Scattered,  then  it  fettled  on  the  ground,  and 
eat  the  feeds,  and  again  repeated  the  fame  management.  Sept. 
*,  1794. 

On  the  northern  coaft  of  Ireland  a  friend  of  mine  faw  abov.? 


120  OF  INSTINCT.        SECT.  XVI.  u.  i. 

a  hundred  crows  at  once  preying  upon  mufcles ;  each  crow- 
took  a  mufcle  up  into  the  air  twenty  or  forty  yards  high,  and 
let  it  fall  on  the  (tones,  and  thus  by  breaking  the  (hell,  got  pof- 
feffion  of  the  animal — A  certain  philofopher  (I  think  it  was 
Anaxagoras)  walking  along  the  fea-fhore  to  gather  (hells,  one  of 
thefe  unlucky  birds  miftaking  his  bald  head  for  a  (lone,  drop- 
ped a  (hell  fi(h  upon  it,  and  killed  at  once  a  philofopher  and  an 
oyfter. 

The  martin,  (hirundo  urbica)  is  faid  by  Linnxus  to  dwell  on 
the  outfide  of  houfes  in  Europe  under  the  eaves,  and  to  return 
with  the  early  foliage.  And  that,  when  it  has  built,  the  fpar- 
row,  fringilla  domeflica,  frequently  occupies  the  fmifhed  neft  ^ 
but  that  the  martin  convoking  its  companions,  while  fome  guard 
the  captive  enemy,  others  bring  clay,  exactly  clofe  up  the  en- 
trance, and  fly  away  leaving  the  intruder  to  be  fuffbcated.  Syft  > 
Natur.  Pad'.  Hirundo.  A  (imilar  relation  was  printed  many 
years  ago  in  the  Gentleman's  Magazine. 

Our  domeflic  animals,  that  have  fome  liberty,  are  alfo  poilefi- 
ed  of  fome  peculiar  traditional  knowledge  :  dogs  and  cats  have 
been  forced  into  each  other's  fociety,  though  naturally  animals 
of  a  very  different  kind,  and  have  hence  learned  from  each  other 
to  eat  dog's  grafs  (agroftis  canina)  when  they  are  (ick,  to  promote 
vomiting.  I  have  feen  a  cat  miftake  the  blade  of  barley  for 
this  grafs,  which  evinces  it  is  an  acquired  knowledge.  They 
have  alfo  learnt  of  each  other  to  cover  their  excrement  and  urine  ; 
— about  a  fpoonful  of  water  was  fpilt  upon  my  hearth  from  the 
tea-kettle,  and  I  obferved  a  kitten  cover  it  with  a(hes.  Hence 
this  mud  aifobe  an  acquired  art  as  the  creature  miftook  the  ap- 
plication of  it. 

To  preferve  their  fur  clean,  and  efpecially  their  whifkers,  cats 
wafluheir  faces,  and  generally  quite  behind  their  ears,  every  time 
they  eat.  As  they  cannot  lick  thofe  places  with  their  tongues, 
they  firft  wet  the  infide  of  the  leg  with  faliva,  and  then  repeat- 
edly wa(h  their  faces  with  it,  which  mud  originally  be  an  effect 
of  reafoning,  becaufe  a  means  is  ufed  to  produce  an  effect  ;  and 
feems  afterwards  to  be  taught  or  acquired  by  imitation,  like  the 
greatefl  part  of  human  arts. 

Thefe  animals  feem  to  pofiefs  fomething  like  an  additional 
fenfe  by  means  of  their  whiflters  ;  which  have  perhaps  fo  ne 
analogy  to  the  antennae  of  moths  and  butterflies.  The  whsfkers 
of  cats  confift  not  only  of  the  long  hairs  on  their  upper  lips,  but 
they  have  alfo  four  or  five  long  hairs  (landing  up  from  each  eye- 
brow, and  alfo  two  or  three  on  each  cheek  j  all  which  when 
the  animal  creels  them,  make  with  their  points  (o  many  parts 
of  the  periphery  of  a  circle,  of  an  extent  at  leail  equal  to  the 

circumference 


SECT.  XVI.  1 1 .  i .         OF  INSTINCT.  1 2 1 

circumference  of  any  part  of  their  own  bodies.  With  this  in- 
ftrument,  I  conceive,  by  a  little  experience,  they  can  at  once  de- 
termine, whether  any  aperture  amongft  hedges  or  (hrubs,  in 
which  animals  of  this  genus  live  in  their  wild  ftate,  is  large 
enough  to  admit  their  bodies  ;  which  to  them  is  a  matter  of 
the  greateft  confequence,  whether  purfuing  or  purfued.  They 
have  likewife  a  power  of  erecting  and  bringing  forward  the  whif- 
kers  on  their  lips;  which  probably  is  for  the  purpofe  of  feeling, 
whether  a  dark  hole  be  further  permeable. 

The  antennae,  or  horns  of  butterflies  and  moths,  who  have 
Awkward  wings,  the  minute  feathers  of  which  are  very  liable  to 
injury,  ferve,  I  fuppofe,  a  fimilar  purpofe  of  meafuring,  as  they 
fly  or  creep  amongft  the  leaves  of  plants  and  trees,  \vhether  their 
wings  can  pafs  without  touching  them. 

I  this  morning  faw  a  terrier  bitch  repeatedly  lick  her  paws, 
and  wafh  her  face  on  both  fides,  and  over  her  eyes,  cxafrly  as  cats 
do  ;  from  whom  I  fuppofe  the  had  acquired  this  art,  as  (he  liv- 
ed in  the  parlour  with  two  of  them. 

Mr.  Leonard,  a  very  intelligent  friend  of  mine,  faw  a  cat 
catch  a  trout  by  darting  upon  it  in  a  deep  clear  water  at  the 
mill  at  Weaford,  near  Litchfield.  The  cat  belonged  to  Mr. 
Stanley,  who  had  often  feen  her  catch  n(h  in  the  fame  manner 
in  Cummer,  when  the  mill-pool,  was  drawn  fo  low  that  the  fifh 
could  be  feen.  I  have  heard  of  other  cats  taking  fifli  in  {hallow 
water,  as  they  flood  on  the  bank.  This  feems  a  natural  art  of 
taking  their  prey  in  cats,  which  their  acquired  delicacy  by  do- 
meftication  has  in  general  prevented  them  from  ufing,  though 
their  defire  of  eating  fiih  continues  in  its  original  ftrength. 

Mr.  White,  in  his  ingenious  Hiftory  of  Selbourne,  was  wit- 
nefs  to  a  cat's  fuckling  a  young  hare,  which  followed  her  about 
the  garden,  and  came  jumping  to  her  call  of  affec'Hon.  At  El- 
ford,  near  Litchfield,  the  Rev,  Mr.  Sawley  had  taken  the  young 
ones  out  of  a  hare,  which  was  (hot;  they  were  alive,  and  the 
cat,  who  had  juft  loll  her  own  kittens,  carried  them  away,  as  it 
was  fuppofed,  to  eat  them  ;  but  it  prefently  appeared,  that  it 
was  affection,  not  hunger  which  incited  her,  as  (he  Cuckled 
them,  and  brought  them  up  as  their  mother. 

Other  inftances  of  the  miftaken  application  of  what  has  been 
termed  inftinft  may  be  obferved  in  flies  in  the  night,  who  mif- 
taking  a  candle  for  day-light,  approach  and  perifh  in  the  flame. 
So  the  putrid  fmell  of  the  ftapelia,  or  carrion-flower,  allures  the 
large  flefh  -fly  to  depofite  its  young  worms  on  its  beautiful  petals, 
which  perifh  there  for  want  of  nourimment.  This  therefore 
cannot  be  a  neceflary  inftinft,  becauCe  the  creature  miftakes  the 
jpplicstion  of  it. 
VOL.  I.  R  Though 


1 2 1  OF  INSTINCT.          SECT.  XVI.  1 1 .  a , 

Though  in  this  country  horfes  (hew  little  veftiges  of  policy, 
yet  in  the  deferts  of  Tartary  and  Siberia,  when  hunted  by  the 
Tartars  they  are  feen  to  form  a  kind  of  community,  fet  watches 
to  prevent  their  being  furprifed,  and  have  commanders,  who 
direct,  and  haften  their  flight.  Origin  of  Language,  Vol.  I.  p. 
2 1  2.  In  this  country  where  four  or  five  horfes  travel  in  a  line, 
the  firit  always  points  his  ears  forward,  and  the  laft  points  his 
backward,  while  the  intermediate  ones  feem  quite  carelefs  in  this 
refpecl  ;  which  feems  a  part  of  policy  to  prevent  furprife.  As 
all  animals  depend  moft  on  the  ear  to  apprize  them  of  the  ap- 
proach of  danger,  the  eye  taking  in  only  half  the  horizon  at 
once,  and  horics  poffefs  a  great  nicety  of  this  fenfe  j  as  appears 
from  their  mode  of  fighting,  mentioned  No  8.  5.  of  this  Sec- 
tion, as  well  as  by  common  ob/ervation. 

There  are  fome  parts  of  a  horfe  which  he  cannot  conveni- 
ently rub,  when  they  itch,  as  about  the  ihoulder,  which  he  can 
neither  *bite  with  his  teeth,  nor  fcratch  with  his  hind  foot ; 
when  this  part  itches,  he  goes  to  another  horfe,  and  gently  bites 
him  in  the  part  which  he  wifhes  to  be  bitten,  which  is  imme- 
diately done  by  his  intelligent  friend,  I  once  obferved  a  young 
foal  thus  bite  its  large  mother,  who  did  not  choofe  to  drop  the 
grafs  (he  had  in  her  mouth,  and  rubbed  her  nofe  againft  the 
foal's  neck  inftead  of  biting  it ;  which  evinces  that  the  knew 
the  defign  of  her  progeny,  and  was  not  governed  by  a  neceffary 
inflinck  to  bite  where  (he  was  bitten. 

Many  of  our  (hrubs,  which  would  other  wife  afford  an  agree- 
able food  to  horfes,  are  armed  with  thorns  or  prickles,  which 
fecure  them  from  thofe  animals ;  as  the  holly,  hawthorn,  goofe- 
berry,  gorfe.  In  the  extenfive  moorlands  of  Stafford  (hire,  the 
horfes  have  learnt  to  ftamp  upon  a  gorfe-bufli  with  one  of  their 
forefeet  for  a  minute  together,  and  when  the  points  are  broken, 
they  eat  it  without  injury.  The  horfes  in  the  new  forelt  in 
Hampshire  are  affirmed  to  do  the  fame  by  Mr.  Gilpin.  Foreft 
Scenery,  II.  25 1,  and  1 12.  Which  is  an  art  other  horfes  in  the 
fertile  parts  of  the  country  do  not  poffefs,  and  prick  their  mouths 
till  they  bleed,  if  they  are  induced  by  hunger  or  caprice  to  at- 
tempt eating  gorfe, 

Swine  have  a  fenfe  of  touch  as  well  as  of  fmell  at  the  end  of 
their  nofe,  which  they  ufe  as  a  hand,  both  to  root  up  the  foil, 
and  to  turn  over  and  examine  objects  of  food,  fomewhat  like  the 
probofcis  of  an  elephant.  As  they  require  fhelter  from  the 
cold  in  this  climate  they  have  learnt  to  collect  ftraw  in  their 
mouths  to  make  their  neft,  when  the  wind  blows  cold  ;  and  to 
call  their  companions  by  repeated  cries  to  aflift  in  the  work,  and 
add  to  their  warmth  by  their  numerous  bed- fellows.  Hence 

*  thefe 


SECT.  XVI.  1 1.  i.          OF  INSTINCT.  123 

thefe  animals,  which  are  efteemed  fo  unclean  have  alfo  learned 
never  to  befoul  their  dens,  where  they  have  liberty,  with  their 
own  excrement  ;  an  art,  which  cows  and  horfcs,  \vhich  have 
open  hovels  to  run  into,  have  never  acquired.  I  have  obierved 
great  fagacity  in  fwine ;  but  the  fhort  lives  we  allou-  them,  and 
their  general  confinement,  prevents  their  improvement,  which 
might  probably  be  otherwife  greater  than  that  of  dogs. 

Inftances  of  the  fagacity  and  knowledge  of  animals  are  very 
numerous  to  every  obferver,  and  their  docility  in  learning  vari- 
ous arts  from  mankind,  evinces  that  they  may  learn  (invliar  arts 
from  their  own  fpecies,  and  thus  be  pofiefled  of  much  acquired 
and  traditional  knowledge 

A  dog  whofe  natural  prey  is  fheep,  is  taught  by  mankind,  not 
only  to  leave  them  unmolefted,  but  to  guard  them  ;  and  to  hunt, 
to  fet,  or  to  deftroy  other  kinds  of  animals,  as  birds,  or  vermin  ; 
and  in  fome  countries  to  catch  fifh,  in  others  to  find  truffles, 
and  to  praclife  a  great  variety  of  tricks  ;  is  it  more  furprifing 
that  the  crows  (hould  teach  each  other,  that  the  hawk  can  catch 
Jefs  birds,  by  the  fuperiour  fwiftnefs  of  his  wing,  and  if  two  oF 
them  follow  him,  till  he  fucceeds  in  his  defign,  that  they  can 
by  force  (hare  a  part  of  the  capture  ?  this  I  have  formerly  ob- 
ferved  with  attention  and  adonifhment. 

There  is  one  kind  of  pelican  mentioned  by  Mr.  OFoeck,  one 
of  Linnaeus's  travelling  pupils  (the  pelican  us  aquilus),  whole 
food  is  fi(h  ;  and  which  it  takes  from  other  birds,  becaufe  it  is 
not  formed  to  catch  them  itfelf;  hence  it  is  called  by  the  Eng- 
li(h  a  Man-of-war-bird,  Voyage  to  China,  p.  88.  There  are 
many  other  interefting  anecdotes  of  the  pelican  and  cormorant, 
collected  from  authors  of  the  bed  authority,  in  a  well-  managed 
Natural  Hiftory  for  Children,  publKhed  by  Mr.  Galton.  John- 
fon.  London. 

And  the  following  narration  from  the  very  accurate  Monf. 
A  dan  fon,  in  his  voyage  to  Senegal, may  gain  credit  with  the  read- 
er :  as  his  employment  in  this  country  was  folely  to  make  ob- 
fervations  in  natural  hiftory.  On  the  river  Niger,  in  his  road  to 
the  ifland  Oriel,  he  fa w  a  great  number  of  pelicans,  or  wide  throats. 
"  They  moved  with  great  (late  like  fwans  upon  the  water,  and 
are  the  largeft  bird  next  to  the  oftrich  ;  the  bill  of  the  one  I  kill- 
ed was  upwards  of  a  foot  and  a  half  long,  and  the  bag  fattened 
underneath  it  held  two  and  twenty  pints  of  water.  They  fwim 
in  flocks,  and  form  a  lar^  ei*cl£,  which  they  contract  afterwards, 
driving  the  fifti  befo|e*them  with  their  legs ;  when  they  fee  the 
fim  in  fufficient  number  confined  in  this  fpace,  they  plunge 
their  bill  wide  opeif  into  the  watefc  and  (hut  it  again  vith  great 

j^N*  qulcknefs, 

%v 


*24  OF  INSTINCT.        SECT.  XVI.  14.  i. 

quicknefs.     They  thus  get  fifh  into  their  throat-bag,  which  they 
cat  afterwards  on  more  at  their  leifure."     P.  247. 

Another  curious  effort  of  defign,  or  ufe  of  means  in  animals, 
is  related  by  Abbe  Grofier,  in  his  Defcription  of  China,  Vol.  I. 
p.  562.  A  kind  of  tiger  is  feen  in  China,  which  has  a  body 
like  a  dog,  but  no  tail,  and  is  remarkably  fwift  and  ferocious. 
If  any  one  meets  this  animal,  and  to  efcape  from  his  fury  climbs 
up  a  tree,  the  tiger  immediately  fends  forth  a  loud  yell,  and  feve- 
ral  other  tigers  arrive  ;  which  all  together  dig  up  the  earth  round 
the  roots  of  the  tree,  and  overturning  it,  feize  their  prey. 

The  rattlefnake  and  black  ferpent  of  America  alfo  ftiould  here 
be  mentioned,  which  are  fuppofed  to  poflefs  an  inftinctive  pow- 
er of  fafcinating  birds  •,  as  many  birds  have  been  feen  repeatedly 
to  run  to  them  and  to  retreat  from  them  with  piteous  (creams, 
till  the  fnake  has  feized  and  devoured  them.  I  formerly  fuf- 
pected,  that  this  ferpent  had  hid  himfelf  in  the  bufhes,  and  had 
fecretly  wounded  the  bird,  and  followed  it  with  his  fteady  eye, 
till  the  poifon  inftilled  into  the  wound  had  time  to  take  effect  ; 
and  that  the  bird  then  fell  from  the  tree  into  his  mouth.  But 
from  an  ingenious  paper,  which  Dr.  B.  S.  Barton,  Profeflbr 
of  Natural  Hiftory,  in  Pennfylvania,  has  favoured  me  with,  and 
•which  will  be  publifhed  in  their  Philofophical  Tranfaclions,  it 
is  clearly  (hewn,  that  this  piteous  cry,  and  approach,  and  retreat, 
of  the  bird  fuppofed  to  be  fafcinated,  is  fimply  an  attack  made 
by  the  female  bird  on  the  ferpent  in  defence  of  her  young  ; 
which  credulity  and  the  love  of  admiration  has  converted  into  a 
prodigy  of  fafcination,  which  is  dill  credited  by  the  multitude 
in  America.  This  circumflance  of  the  mother  bird  daring  to 
defend  her  young  from  a  ferpent,  till  (he  was  devoured  by  him, 
and  her  fcreaming  around  him,  is  defcribed  by  that  great  ob- 
ferver  of  nature,  the  immortal  Homer,  above  2000  years  ago. 
Iliad.  Lib.  2.1.  310. 

XII.  The  knowledge  and  language  of  thofe  birds,  that  fre- 
quently change  their  climate  with  the  feafons,  is  ftiil  more  ex- 
tenfive  *,  as  they  perform  thefe  migrations  in  large  focieties,  and 
are  lefs  fubje£t  to  the  power  of  man,  than  the  refident  tribes  of 
birds.  They  are  faid  to  follow  a  leader  during  the  day,  wjio  is 
occafionally  changed,  and  to  keep  a  continual  cry  during  the 
night  to  keep  themielves  together.  It  is  probable  that  thefe 
emigrations  were  at  firft  undertaken  as  accident  directed,  by  the 
more  adventurous  of  their  fpecies^j^jtearned  from  one  another 
like  the  difcoveries  of  mankind  in  navigation.  The  following 
circumftances  ftrongly  fuppo^^H.  opinion.^ 

i.  Nature  has  provided  thflH  Imals,  in*the  climates  where 
they  ate  produced ?  with  anotHiM 'efource,  ^vhen  the  feafon  be- 

^fim-  .^r  comes 


SECT.  XVI.  12.  2.        OF    INSTINCT.  125 

comes  too  cold  for  their  ccnftitutions,  or  the  food  they  \vere  fup- 
ported  with  ceafes  to  be  fupplied  :  I  mean  that  of  fleeping. 
D  >rmice,  fnakes  and  bats,  have  not  the  means  of  changing  their 
country  ;  the  two  former  from  the  want  of  wings,  and  the  lat- 
ter from  his  being  not  able  to  bear  the  light  of  the  day.  Hence 
thefe  animals  are  obliged  to  make  ufe  of  this  refource,  and  deep 
during  the  winter.  And  thofe  fwallows  that  have  been  hatched 
too  late  in  the  year  to  acquire  their  full  ttrength  of  pinion,  or  that 
have  been  maimed  by  accident  or  difeafe,  have  been  frequently 
found  in  the  hollows  of  rocks  on  the  fea  coafts,  and  even  under 
•water  in  this  torpid  ftate,  from  which  they  have  been  revived 
by  the  warmth  of  a  fire.  This  torpid  flate  of  fwallows  is  tefti- 
fied  by  innumerable  evidences  both  of  ancient  and  modern 
names.  Ariitotle,  fpeaking  of  the  fwallows  fays,  "  They  pafs 
ii»to  warmer  climates  in  winter,  if  fuch  places  are  at  no  great 
diftance  ;  if  they  are,  they  bury  themfelves  in  the  climates  where 
they  dwell,"  (8.  Hift.  c.  16.  See  alfo  Derham's  Phyf.  TheoL 
v.  ii.  p.  177.) 

The  hybernation  of  animals  is  mentioned  by  M.  Fabricius, 
who  fuppofes  it^only  to  happen  to  animals,  which  originally  be- 
longed to  a  warmer  climate,  and  adds,  that  when  thefe  animals 
are  carried  back  to  a  warmer  climate,  and  fupplied  plentifully 
>lfith  food,  they  ceafe  to  hybernate. 

Hence  their  emigrations  cannot  depend  on  a  neceffary  inftincT:, 
as  the  emigrations  themfelves  are  notneceffary. 

2.  When  the  weather  becomes  cold,  the  fwallows  in  the 
neighbourhood  aflemble  in  large  flocks  ;  that  is,  the  unexperi- 
enced attend  thofe  that  have  before  experienced  the  journey  they 
are  about  to  undertake  :  they  are  then  feen  fome  time  to  hover 
en  the  coaft,  till  there  is  calm  weather,  or  a  wind,  that  fuits  the 
direction  of  their  flight.  Other  birds  of  paflage  have  been 
drowned  by  thoufands  in  the  fea,  or  have  fettled  on  (hips  quite 
exhaulted  with  fatigue.  And  others,  either  by  miftaking  their 
courfe,  or  by  diftreis  of  weather,  have  arrived  in  countries  where 
they  were  never  feen  before  :  and  thus  are  evidently  fubjecl  to 
the  fame  hazards  that  the  human  fpecies  undergo,  in  the  execu- 
tion of  their  artificial  purpofes. 

3  The  fame  birds  are  emigrant  from  fome  countries  and  not 
fo  from  others  :  the  fwallows  were  feen  at  Goree  in  January  by 
an  ingenious  philofopher  of  my  acquintance,  and  he  was  told 
that  they  continued  thereallthe  year  ;  as  the  warmth  of  the  cli- 
mate was  at  all  feaf<H|^M|fctt  for  their  own  conftiuuions,  and 
for  the  produtliorf  of  the  xiUe»hat  fupply  them  with  nourifh- 
ment.  Herodocus  fays,  that  iwLybia,  about  the  fprings  of  the 
Nile,  the  fwallows  continujipBne  year.  (L.  ?..") 

Quails 


126  OF  INSTINCT.        SECT.  XVI.  12.  3. 

Quails  (tetrao  coturnix,  Lin.)  are  birds  of  pafTage  from  the 
coalt  of  Barbary  to  Inly,  and  have  frequency  fettled  in  large 
fhoals  on  (hips  fatigued  \vith  their  flight.  (Ray,  Wifdo'n  of 
God,  p.  129.  Derham  Phyfic,  Theol.  v.  ii.  p  178.)  Dr  Ruf- 
fel,  in  his  hitlory  of  Aleppo,  obferves  that  the  fwailows  vifit  that 
country  about  the  end  of  February,  and  having  hatched  their 
young  difappear  about  the  end  of  July  ;  and  returning  again 
about  the  beginning  of  October,  continue  about  a  fortnight,  and 
then  again  difappear.  (P  70.) 

When  my  late  friend  Dr.  Chambres  of  Derby  was  on  the 
iiland  of  Caprea  in  the  bay  of  Naples,  he  was  informed  that  great 
flights  of  quails  annually  fettle  on  that  ifland  about  the  begin- 
ning of  May,  in  their  oalTage  from  Africa  to  Europe.  And  that 
they  always  come  when  the  fouth-eaft  wind  blows,  are  fatigued 
when  they  red  on  this  ifland,  and  are  taken  in  fuch  amazing 
quantities  and  fold  to  the  Continent,  that  the  inhabitants  pay 
the  bilhop  his  ftipend  out  of  the  profits  arifing  from  the  fale  of 
them 

The  flights  of  thefe  birds  acrofs  the  Mediterranean  are  record- 
ed near  three  thoufand  years  ago  u  There  went  forth  a  wind 
from  the  Lord  and  brought  quails  from  the  fea,  and  let  them  fall 
upon  the  camp,  a  day's  journey  round  about  it,  and  they  were 
two  cubits  above  the  earth,"  (Numbers,  chap,  ii  ver.  31.) 

In  our  country,  Mr.  Pennant,  informs  us,  that  fome  quails 
migrate,  and  others  only  remove  from  the  internal  parts  of  the 
ifland  to  the  coafts,  (Zoology,  oftavo,  210.)  Some  of  the  ring- 
doves and  (lares  breed  here,  others  migrate,  (ibid.  510,  511.) 
And  the  flender  billed  fmall  birds  do  not  all  quit  thefe  kingdoms 
in  the  winter,  though  the  difficulty  of  procuring  the  worms  and 
infecls,  that  they  feed  on,  fuppiies  the  fame  reafon  for  migra- 
tion to  them  all,  (ibid.  511.) 

Linnaeus  has  obferved,  that  in  Sweden  the  female  chaffinches 
quit  that  country  in  September,  migrating  into  Holland,  and 
leave  their  mates  behind  till  their  return  in  fpring.  Hence  he 
has  called  them  Fringilla  cselebs,  (  Amoen.  Acad.  ii/42.  iv.  595. ) 
No  win  our  climate  both  fexes  of  them  are  perennial  birds.  And 
Mr.  Pennant  obferves  that  the  hoopoe,  chatterer,  hawfinch,  and 
crofs-bill,  migrate  into  England  fo  rarely,  and  at  fuch  uncertain 
times,  as  not  to  deferve  to  be  ranked  among  our  birds  of  paf- 
fage,  (Zool.  8vo.  511.) 

The  water  fowl,  as  geefe  and  ducks,  are  better  adapted  for 
long  migrations,  than  the  ..other  #fi>es  of  birds,  as,  when  the 
weather  is  calm,  they  can  notot%  reft  themfelves,  or  fleep  upon 
the  ocean,  but  poflibly  procure  f%me  kind  of  food  from  it. 

Hence  in  Siberia,  as  foon  as  f&e  lakes  are  frozen,  the  water 

fowlj 


SECT.  XVI.  12, 3.          OF  INSTINCT.  1*7- 

fowl  which  are  very  numerous,  all  difappear,  and  are  fuppofed 
to  fly  to  warmer  climates,  excepfothe  rail,  which,  from  its  inabil- 
ity for  long  flights,  probably  fleeps,  like  our  bat,  in  their  winter. 
The  following  account  from  the  Journey  of  Piofeflbr  Gmelin, 
may  entertain  the  reader.  "  In  the  neighbourhood  of  Krafnoi- 
ark,  amongit  many  other  emigrant  water  fowls  we  obferved  a 
great  number  of  rails,  which  when  purfued  never  took  flight, 
but  endeavoured  to  efcape  by  running*  We  inquired  how  thefe 
birds,  that  could  not  fly,  could  retire  into  other  countries  in  the 
winter,  and  were  told,  both  by  the  Tartars  and  Aflanians,  that 
they  well  knew  thofe  birds  could  not  alone  pats  into  other  coun- 
tries :  but  when  the  cranes  (les  grues)  retire  in  autumn,  each  one 
takes  a  rail  (un  rale)  upon  his  back,  and  carries  him  to  a  warmer 
climate/' 

Recapitulation. 

1.  All  birds  of  pafTage    can  exift  in  the  climates,  where  they 
are  produced. 

2.  They  are  fubjeft  in  their  migrations  to  the  fame  accidents 
and  difficulties,  that  mankind  are  fubjecffc  to  in  navigation. 

3.  The  fame   fpecies  of  birds  migrate  from  fame  countries, 
and  are  refident  in  others. 

From  all  thefe  circumitances  it  appears  that  the  migrations  of 
birds  are  not  produced  by  a  neceflary  inflinct,  but  are  acciden- 
tal improvements,  like  the  arts  among  mankind,  taught  by  their 
contemporaries,  or  delivered  by  tradition  from  one  generation 
of  them  to  another. 

XIIL  In  that  feafon  of  the  year  which  fupplies  the  nourifh- 
ment  proper  for  the  expected  brood,  the  birds  enter  into  a  con- 
trad!  of  marriage,  and  with  joint  labour  conftrutt  a  bed  for  the 
reception  of  their  offspring.  Their  choice  of  the  proper  feafon, 
their  contracts  of  marriage,  and  the  regularity  with  which  they 
conrtruft  their  nefts,  have  in  all  ages  excited  the  admiration  of 
naturalifts  ;  and  have  always  been  attributed  to  the  power  of  in- 
ft  i  lid,  which,  like  the  occult  qualities  of  the  ancient  philofo- 
phers,  prevented  all  further  inquiry.  We  fhall  confider  them 
in  their  order. 

Their  Choice  of  the  Seafon. 

Our  domeftic  birds,  that  are  plentifully  fupplied  throughout 
the  year  \virh  their  adapted  food,  and  are  covered  with  houfes 
from  the  inclemency  of  the  weather,  lay  their  eggs  at  any  fea- 
fon :  which  evinces  that  the  fpring  of  the  year  is  not  pointed 
out  to  them  by  a  neceflary  inftinct 

Whilft 


128  OF  INSTINCT.        SECT.  XVI.  13.  i. 

WhiHl:  the  wild  tribes  of  birds  choofe  this  time  of  the  year 
from  their  acquired  knowledge,  that  the  mild  temperature  of  the 
air  is  more  convenient  for  hatching  their  eggs,  and  is  foon  likely 
tofupply  that  kind  of  nourifhment,that  is  wanted  for  their  young. 

If  the  genial  warmth  of  the  fpring  produced  the  paifion  of 
love,  as  it  expands  the  foliage  of  trees,  all  other  animals  mould 
feel  its  influence  as  well  as  birds :  bur,  the  viviparous  creatures, 
as  they  fuckle  their  young,  that  is,  as  they  previously  digeft  the 
natural  food,  that  it  may  better  fuit  the  tender  ftomachs  of  their 
offsping,  experience  the  influence  of  this  paflion  at  all  -feafons 
of  the  year,  as  cats  and  bitches.  The  graminivorous  animals 
indeed  generally  produce  their  young  about  the  time  when  grafs 
is  fupplied  in  the  greatefl  plenty,  but  this  is  without  any  decree 
of  exa£tnefs,  as  appears  from  our  cows,  flieep  and  hares,  and 
may  be  a  part  of  the  traditional  knowledge,  which  they  learn 
from  the  example  of  their  parents. 

Their  Contrafts  of  Marriage. 

Their  mutual  paflion,  and  the  acquired  knowledge,  that  their 
joint  labour  is  neceflary  to  procure  fuftenance  for  their  nume- 
rous family,  induces  the  wild  birds  to  enter  into  a  contract  of 
marriage,  which  does  not  however  take  place  among  the  ducks, 
geefe,  and  fowls,  that  are  provided  with  their  daily  food  from 
our  barns. 

An  ingenious  philofopher  has  lately  denied  that  animals  can 
enter  into  contracts,  and  thinks  this  an  eflential  difference  be- 
tween them  and  the  human  creature  : — but  does  not  daily  ob- 
fervation  convince  us,  that  they  form  contracts  of  friend  fhip 
with  each  other,  and  with  mankind  ?  When  puppies  and  kittens 
play  together,  is  there  not  a  tacit  contract,  that  they  will  not 
hurt  each  other  ?  And  does  not  your  favourite  dog  expect  you 
ihould  give  him  his  daily  food,  for  his  fervices  and  attention  to 
you  ?  And  thus  barters  his  love  for  your  protection  ?  In  the 
fame  manner  that  all  contracts  are  made  amongii  men,  that  do 
not  underftand  each  other's  arbitary  language. 

The  ConftruSKon  of  their  Nefts. 

i.  They  feem  to  be  inftrufted  how  to  build  their  nefts  from 
their  obfervation  of  that,  in  which  they  were  educated,  and  from 
their  knowledge  of  thofe  things,  that  are  molt  agreeable  to  their 
touch  in  refpect  to  warmth,  cleanlinefs,  and  (lability.  They 
choofe  their  fituations  from  their  ideas  of  fafety  from  their  ene- 
mies, and  of  fhelter  from  the  weather.  Nor  is  the  colour  of 

their 


S£CT.  XVI.  13.  2.          OF  INSTINCT.  up 

their  nefts  a  circumftance  unthought  of  j  the  finches,  that  build 
in  green  hedges,  cover  their  habitations  with  green  mofs  ;  the 
fwallow  or  martin,  that  builds  againfl  rocks  aiig  houfes,  covers 
hers  with  clay,  whilft  the  lark  choofes  vegetable  draw  nearly  of 
the  colour  of  the  ground  (lie  inhabits  :  by  this  contrivance,  they 
are  all  lefs  liable  to  be  difcovered  by  their  adverfaries. 

2.  Nor  are  the  nefts  of  the  fame  fpecies  of  birds  conftrufted 
always  of  the  fame  materials,  nor  in  the  fame  form ;  which  is 
another  circumftance  that  afcertains,  that  they  are  led  by  obfer- 
vation. 

In  the  trees  before  Mr.  Levet's  houfe  in  Litchfield,  there  are 
annually  nefts  built  by  fparrows,  a  bird  which  ufuaily  builds  un- 
der the  tiles  of  houfes',  or  the  thatch  of  barns.  Not  finding  fuch 
convenient  fituations  for  their  nefts,  they  build  a  covered  neft 
bigger  than  a  man's  head,  with  an  opening  like  a  mouth  at  the. 
fide,  refembling  that  of  a  magpie,  except  that  it  is  built  with 
ftraw  and  hay,  and  lined  with  feathers,  and  fo  nicely  managed 
as  to  be  a  defence  againft  both  wind  and  rain. 

The  following  extract  from  a  Letter  of  the  Rev.  Mr.  J.  Dar- 
win, of  Carleton  Scroop,  in  Lincolnfhire,  authenticates  a  curious 
fad  of  this  kind.  "  When  I  mentioned  to  you  the  circum- 
ftance of  crows  or  rooks  building  in  the  fpire  of  Welbourn 
church,  you  exprefled  a  defire  of  being  well  informed  of  the 
certainty 'of  the  fad.  Weibourn  is  fituated  in  the  road  from 
Grantham  to  Lincoln,  on  the  Cliff  row  ;  I  yefterday  took  a  ride 
thither,  and  inquired  of  the  redor,  Mr.  Ridgehill,  whether  the 
report  was  true,  that  rooks  built  in  the  fpire  of  his  church.  He 
afTured  me  it  was  true,  and  that  they  had  done  fo  time  imme- 
morial, as  his  parifhioners  affirmed.  There  was  a  common  tra- 
dition, he  faid,  that  formerly  a  Cookery  in  fome  high  trees  ad- 
joined the  church  yard,  which  being  cut  down,  (probably  in  the 
fpring,  the  building  feafon),  the  rooks  removed  to  the  church, 
and  built  their  nefts  on  the  outfide  of  the  fpire  on  the  tops  of 
windows,  which  by  their  proje£Uon  a  little  from  the  fpire  made 
them  convenient  room,  but  that  they  built  alfo  on  the  infide.  I 
faw  two  nefts  made  with  fticks  on  the  outfide,  and  in  the  fpires, 
and  Mr.  Ridgehill  faid  there  were  always  a  great  many. 

"  I  fpent  the  day  with  Mr.  Wright,  a  clergyman,  at  Fulbeck, 
near  Welbourn,  and  in  the  afternoon,  Dr.  Ellis  of  Leadenham^ 
about  two  miles  from  Welbourn,  drank  tea  at  Mr.  Wright's,  who 
faid  he  remembered,  when  Mr.  Weihy  lived  at  Welbourn,  that 
he  received  a  letter  from  an  acquaintance  in  the  weft  of  Eng- 
land, defining  an  anfwer,  whether  the  report  of  rooks  building 
in  Welbourn  church  was  true,  as  a  wager  was  depending  on 

VOL.  I.  S  that 


j  30  OF  INSTINCT.          SECT.  XVI.  13.  z. 

that  fubjecl  ;  to  which  he  returned  an  anfwer  afcertaining  the 
fact,  and  decided  the  wager."  Aug.  30,  1794. 

So  the  jackdaw  (corvus  monedula)  generally  builds  in  church 
fteeples,  or  under  the  roofs  of  high  houfes ;  but  at  Selbourn,  in 
Southamptonfhire,  where  towers  and  fteeples  are  not  fufficiently 
numerous,  thefe  birds  build  in  forfaken  rabbit  burrows.  See  a 
curious  account  of  thefe  fubterranean  nefts  in  White's  Hiftory 
of  Selbourn,  p.  59.  Can  the  Ikilful  change  of  architecture  in, 
thefe  birds  and  the  fparrows  above  mentioned  be  governed  by 
inftinc~l  ?  Then  they  mud  have  two  inftincts,  one  for  common, 
and  the  other  for  extraordinary  occafions. 

I  have  feen  green  worfted  in  a  neft,  which  no  where  exifts  in 
nature :  and  the  down  of  thiflles  in  thofe  nefts,  that  were  by 
feme  accident  conftru&ed  later  in  the  fummer,  which  material 
could  not  be  procured  for  the  earlier  nefts  :  in  many  different 
climates  they  cannot  procure  the  fame  materials,  that  they  ufe  in 
ours.  And  it  is  well  known,  that  the  canary  birds,  that  are  prop- 
agated in  this  country,  and  the  finches  that  are  kept  tame,  will 
build  their  nefts  of  any  flexile  materials,  that  are  given  them. 
Plutarch,  in  his  Book  on  Rivers,  fpeaking  of  the  Nile,  fays, 
"  that  the  fwallows  collect  a  material,  when  the  waters  recede, 
with  which  they  form  nefts,  that  are  impervious  to  water."  And 
in  India  there  is  a  fwallow  that  collects  a  glutinous  fubftance 
for  this  purpofe,  whofe  neft  is  efculent,  and  efteemed  a  princi- 
pal rarity  amongft  epicures,  (Lin.  Syft.  Nat.)  Both  thefe  muft  be 
conftrufted  of  very  different  materials  from  thofe  ufed  by  the 
fwallows  of  our  country. 

In  India  the  birds  exert  more  artifice  in  building  their  nefts  on 
account  of  the  monkeys  and  fnakes  :  fome  form  their  penfile 
nefts  in  the  fhape  of  a  purfe,  deep  and  open  at  top  ;  others  with 
a  hole  in  the  fide  ;  and  others,  ftill  more  cautious,  with  an  en- 
trance at  the  very  bottom,  forming  their  lodge  near  the  fummit. 
But  the  taylor-bird  will  not  even  truft  its  neft  to  the  extremity 
of  a  tender  twig,  but  makes  one  more  advance  to  fafety  by  fix- 
ing it  to  the  leaf  itfelf.  It  picks  up  a  dead  leaf  and  lews  it  to 
the  fide  of  a  living  one,  its  ilender  bill  being  its  needle,  and  its 
thread  fome  fine  fibres  •,  the  lining  confifts  of  feathers,  golTamer, 
and  down ;  its  eggs  are  white,  the  colour  of  the  bird  light  yel- 
low, its  length  three  inches,  its  weight  three  fixteenths  of  an 
ounce  ;  fo  that  the  materials  of  the  neft,  and  the  weight  of  the 
bird,  are  not  likely  to  draw  down  an  habitation  fo  ilightly  fuf- 
pended.  A  neft  of  this  bird  is  preferved  in  the  Britifh  Mufe- 
um,  (Pennant's  Indian  Zoology.)  This  calls  to  one's  mind  the 
Mofaic  account  of  the  origin  of  mankind,  the  fir  ft  dawning  of 
;>rt  there  afcribed  to  them,  is  that  of  fewing  leaves  together. 

For 


SECT.  XVI.  13. 3.          OF  INSTINCT.  I3r 

For  many  other  curious  kinds  of  nefts  fee  Natural  IJiftory  for 
Children,  by  Mr.  Gallon.  Johnfton.  London.  Part  I.  p.  47. 
Gen.  Oriolus. 

3.  Thofe  birds  that  are  brought  up  by  our  care,  and  have  had 
little  communication  with  others  of  their  own  fpecies,  are  very 
defective  in  this   acquired  knowledge  ;    they  are  not  only  very 
awkward  in  the  conftruclion  of  their  nefts,  but  generally  fcatter 
their  eggs  in  various  parts  of  the  room  or  cage,  where  they  are 
confined,  and  feldom  produce  young  ones,  till,  by  failing  in  their 
firft  attempt,  they  have  learnt  fomething  from  their  own  obfer- 
vation. 

4.  During  the  time  of  incubation  birds  are  faid  in  general  to 
turn  their  eggs  every    day  ;   fome  cover  them,  when  they  leave 
the  neft,  as  ducks  and  geele  ;  in  fome  the  male  is  faid  to  bring 
food  to  the  female,   that  (he  may  have  lefs  occafion  of  abfence, 
in  others,  he  is  faid  to  take  her  place,  when  {lie  goes  in  queft  of 
food  ;  and  all  of  them  are  faid  to  leave  their  eggs  a  fhorter  time 
in  cold  weather  than  in  warm.     In 'Senegal  the  oftrich  fits  on 
her  eggs  only  during  the  night,  leaving  them  in  the  day  to  the 
heat  of  the  fun  ;  but  at  the  Cape  of  Good  Hope,  where  the  heat 
is  lefs,  (lie  fits  on  them  day  and  night. 

If  it  fhould  be  aiked  what  induces  a  bird  to  fit  weeks  on  its 
firil  eggs  unconfcious  that  a  brood  of  young  ones  will  be  the 
product  ?  The  anfwer  mud  be,  that  it  is  the  fame  paflion  that 
induces  the  human  mother  to  hold  her  offspring  whole  nights 
and  days  in  her  fond  arms,  and  prefs  it  to  her  bofom,  uncon- 
fcious of  its  future  growth  to  fenfe  and  manhood,  till  obferva- 
tion  or  tradition  have  informed  her. 

5.  And  as  many  ladies  are  too  refined  to   nurfe   their  own 
children,  and  deliver  them  to  the  care  and  provifion  of  others  ; 
fo  is  there  one  inftance  of  this  vice  in  the  feathered  world.     The 
cuckoo  in  fame  parts  of  England,   as  I  am  well  informed  by  a 
very  diftincl  and  ingenious  gentleman,  hatches  and  educates  her 
young  ;  whilft  in  other  parts  (he  builds  no  neft,  but  ufes  that  of 
fome  letter  bird,  generally  either  of  the  wagtail  or  hedge  fpar- 
row,  and  depofiting  one  egg  in  it,  takes  no   further  care  of  her 
progeny. 

M.  Heriflant  thought,  that  he  had  difcovered  the  reafon,  why 
cuckoos  do  not  incubate  their  own  eggs,  by  having  obferved  that 
the  crop  or  ftomach  of  the  cuckoo  was  placed  behind  the  fter- 
num,  or  breaft-booe,  and  he  thence  fancied,  that  this  would 
render  incubation  difagreeable  or  impracticable.  Hift.  de  F 
Acad.  Royal.  1752.  But  Mr.  White,  in  his  Natural  Hiftory  of 
Selbourn,  aflerts,  that  on  diflecting  a  fern-owl  he  found  the  fitu- 
ition  of  the  crop  or  ftornach  of  that  bird  to  be  behind  the  fter- 

num, 


1 3*  Of  INSTINCT.          SECT.  XVI.  13. 5. 

num,  like  that  of  the  cuckoo,  and  fuppofes  that  many  other 
birds  may  be  organized  in  the  fame  manner.  -And,  as  the  fern- 
owl incubates  and  hatches  her  own  eggs,  he  rationally  concludes, 
that  this  ftruclure  of  the  bird  cannot  be  the  caufe  of  her  want 
of  maternal  ftorge,  Hift.  of  Selbourn,  p.  208. 

As  the  Rev.  Mr.  Stafford  was  walking  in  Glofop  Dale,  in  the 
Peak  of  Derbyfhire,  he  faw  a  cuckoo  rife  from  its  neft.  The 
rieft  was  on  the  flump  of  a  tree,  that  had  been  fome  time  felled, 
among  fome  chips  that  were  in  part  turned  grey,  fo  as  much  to 
referable  the  colour  of  the  bird  ;  in  this  neft  were  two  young 
cuckoos  •,  tying  a  firing  about  the  leg  of  one  of  them,  he  peg- 
ged the  other  end  of  it  to  the  ground,  and  very  frequently  for 
many  days  beheld  the  old  cuckoo  feed  thefe  young,  as  he  Hood 
very  near  them. 

The  following  extract  of  a  Letter  from  the  Rev.  Mr.  Wilmot, 
of  Morley,  near  Derby,  ftrengthens  the  truth  of  the  fact  above 
mentioned,  of  the  cuckoo  fometimes  making  a  neft,  and  hatch- 
ing her  own  young. 

"  In  the  beginning  of  July  1792,  I  was  attending  fome  la- 
bourers on  my  farm,  when  one  of  them  faid  to  rne,  "  There  is 
a  bird's  neft  upon  one  of  the  Coal-flack  Hills  ;  the  bird  is  now 
fitting,  and  is  exactly  like  a  cuckoo.  They  fay  that  cuckoos 
never  hatch  their  own  eggs,  otherwife  I  mould  have  fworn  it 
was  one."  He  took  me  to  the  fpot,  it  was  in  an  open  fallow 
ground  \  the  bird  was  upon  the  neft,  I  ftood  and  obferved  her 
fome  time,  and  was  perfectly  fatisfied  it  was  a  cuckoo  ;  I  then 
put  my  hand  towards  her,  and  fhe  almoft  let  me  touch  her  be- 
fore me  rofe  from  the  neft,  which  (he  appeared  to  quit  with  great 
uneafinefs,  fkimming  over  the  ground  in  the  manner  that  a  hen 
partridge  does  when  difturbed  from  a  new  hatched  brood,  and 
went  only  to  a  thicket  about  forty  or  fifty  yards  from  the  neft  ; 
and  continued  there  as  long  as  I  flayed  to  obferve  her,  which  was 
not  m^ny  minutes.  In  the  neft,  which  was  barely  a  hole  fcratch- 
ed  out  of  the  cole  flack  in  the  manner  of  a  plover's  neft,  I  ob- 
ferved three  eggs,  but  did  not  touch  them.  As  I  had  labourers 
conftantly  at  work  in  that  field,  I  went  thither  every  day,  and  al- 
ways looked  to  fee  if  the  bird  was  there,  but, did  not  dift^rbher 
for  feven  or  eight  days,  when  I  was  tempted  to  drive  her  from 
the  neft,  and  found  tivo  young  ones,  that  appeared  to  have  been 
hatched  fome  days,  but  there  was  no  appearance  of  the  third  egg. 
I  then  mentioned  this  extraordinary  circumftance  (for  fuch  I 
thought  it)  to  Mr.  and  Mrs.  Holyoak  of  Bidford  Grange,  War- 
wickfhire,  and  to  Mifs  M.  Willes,  who  were  on  a  vifit  at  my 
houfe,  and  who  all  went  to  fee  it.  Very  lately  I  reminded  Mr. 
Holyoak  of  it,  who  told  me  he  had  a  perfect  recollection  of 

the 


SECT.  XVI.  14-  I-          OF  INSTINCT.  133 

the  whole,  and  that,  confidering  it  a  curiofity,  he  walked  to 
look  at  it  feveral  times,  was  perfe&ly  fatisfied  as  to  its  being  a 
cuckoo,  and  thought  her  more  attentive  to  her  young,  than  any 
other  bird  he  ever  observed,  having  always  found  her  brooding 
her  young.  In  about  a  week  after  I  firft  faw  the  young  ones, 
one  of  them  was  miffing,  and  I  rather  fufpefted  my  plough-boys 
having  taken  it  ;  though  it  might  poffibly  have  been  taken  by  a 
hawk,  fometime  when  the  old  one  was  feeking  food.  I  never 
found  her  off  her  neft  but  once,  and  that  was  the  lad  time  I  faw 
the  remaining  young  one,  when  it  was  almoft  full  feathered.  I 
then  went  from  home  for  two  or  three  days,  and,  when  I  return- 
ed, the  young  one  was  gone,  which  I  take  for  granted  had  flown, 
Though  during  this  time  I  frequently  faw  cuckoos  in  the  thick- 
et I  mention,  I  never  obferved  any  one,  that  I  fupjpoied  to  be  the 
cock-bird,  paired  with  this  hen  " 

Nor  is  this  a  new  obfervation,  though  it  is  entirely  overlooked 
by  the  modern  naturalifis,  for  Ariftotle  fpeaking  of  the  cuckoo, 
aflerts  that  (he  fometimes  builds  her  neft  among  broken  rocks, 
and  on  high  mountains,  (L.  6.  H.  c.  i.)  but  adds  in  another 
place  that  ihe  generally  poffefles  the  neft  of  another  bird,  (L.6, 
H.  c.  7.)  And  Niphus  fays  that  cuckoos  rarely  build  for  them- 
felves,  moft  frequently  laying  their  eggs  in  the  nefls  of  other 
birds,  (Gefner,  L.  3.  deCuculo.) 

The  Philofopher  who  is  acquainted  with  thefe  f<i£ts  concern- 
ing the  cuckoo,  would  feem  to  have  very  little  reajon  himfelf,  if 
he  could  imagine  this  neglecT:  of  her  young  to  be  a  neceflary 
inftinft  t 

XIV.  The  deep  recefles  of  the  ocean  are  inacceflible  to  man- 
kind, which  prevents  us  from  having  much  knowledge  of  the 
arts  and  government  of  its  inhabitants. 

1.  One  of  the  baits  ufed  by  the  fimerman  is  an  animal  called 
an  Old  Soldier  ;  his  fize  and  form  are  fomewhat  like  the  craw- 
fifli,  with  this  difference,   that  his  tail  is  covered  with  a  tough 
membrane  inftead  of  a  fhell ;  and  to  obviate  this  defecl:,he  feeks 
out  the  uninhabited  fhell  of  fome  dead  fifh,  that  is  large  enough 
to  receive  his  tail,   and  car  ries  it  about  with  him  as  part  of  his 
clothing  or  armojir. 

2.  On  the  coafts  about    Scarborough,  where  the  haddocks, 
cods,  and  dog- fifh,  are  in  great  abundance,  the  fifhermen  univer- 
fally  believe  that  the  dog-fifh  make  a  line,  or  femicifcle,  to  en- 
compafs  a  fhoal  of  haddocks    and   cod,  confining  them  within 
certain  limits  near  the   fhore,  and  eating  them  as  occafion  re- 
quires.    For   the  haddocks  and  cod   are  always  found  near  the 
fhore  without  any  dog-fifh  among  them,  and  the  dog-fifh  further 
off  without  any  haddocks  or  cod  ;  and  yet  the  former  are  known 

to 


134  OF  INSTINCT.        SECT.  XVI.  14.  3. 

to  prey  upon  the  latter,  and  in  fome  years  devour  fuch  immenfe 
quantities  as  to  render  this  fifhery  more  expenfive  than  profita- 
ble. 

3.  Theremora,  when  he  wifhes  to  remove  his  fituation,  as 
he  is  a  very  flow   fwimmer,  is   content  to  take  an  outfide  place 
on  whatever  conveyance  is  going  his  way  ;  nor  can  the  cunning 
animal  be  tempted  to  quit  his  hold  of  a  fhip  when  (he  is  failing, 
not  even  for  the  lucre  of   a  piece  of  pork,  left  it  fhould  endan- 
ger the  lofs  of  his  paflage  :  at  other  times  he  is  eafily  caught  with 
the  hook. 

4.  The  crab-fifh,  like  many  other  teftaceous  animals,  annu- 
ally changes   its  fhell ;  it  is   then  in  a  (oft   flare,  covered  only 
with  a  mucous    membrane,    and  conceals  itfelf  in  holes  in  the 
fand  or  under  weeds  ;  at  this  place  a  hard  (helled  crab  always 
ftands  centinel,  to  prevent  the  fea  infe&s  from  injuring  the  other 
in  its  defencelefs  ftate  ;  and  the  fifhermen  from  his  appearance 
know  where  to  find   the  foft  ones,  which  they  ufe  for  baits  in 
catching  other  fifh. 

And  though  the  hard  flielled  crab,  when  he  is  on  this  duty, 
advances  boldly  to  meet  the  foe,  and  will  with  difficulty  quit 
the  field  ;  yet  at  other  times  he  fliews  great  timidity,  and  has  a 
wonderful  fpeed  in  attempting  his  efcape  ;  and,  if  often  inter- 
rupted, will  pretend  death  like  the  fpider,  and  watch  an  oppor- 
tunity to  fink  himfelf  into  the  fand,  keeping  only  his  eyes  above. 
My  ingenious  friend  Mr.  Burdett,  who  favoured  me  with  thefe 
accounts  at  the  time  he  was  furveying  the  coafts,  thinks  the 
commerce  between  the  (exes  takes  place  at  this  time,  and  in- 
fpires  the  courage  of  the  creature. 

5.  The  (hoals  of  herrings,  cods,  haddocks,    and  other  fiili, 
which  approach  our  ihores  at  certain  feafons,  and  quit  them  at 
other  feafons  without  leaving  one  behind  ;  and  the  falmon,  that 
periodically  frequent  our   rivers,  evince,  that  there  are  vagrant 
tribes  of  fifh,  that  perform  as  regular  migrations  as  the  birds  of 
paflage  already  mentioned. 

6.  There  is   a  cataract  on  the  river  Liffey  in  Ireland  about 
nineteen  feet  high  :  here  in  the  falmon  feafon  many  of  the  inhab- 
itants amufe  themfelves  in  obferving  thefe  fifh  leap  up  the  tor- 
rent.    They  dart  themfelves  quite  out  of  the  water  as  they  af- 
cend,  and  frequently  fall  back  many  times  before  they  furmount 
it,  and  balkets  made  of  twigs  are  placed  near  the  edge  of  the 
ft  ream  to  catch  them  in  their  fall. 

I  have  obferved,  as  I  have  fat  by  a  fpout  of  water,  which  de- 
fcends  from  a  ftone  trough  about  two  feet  into  a  ftream  below, 
at  particular  feafons  of  the  year,  a  great  number  of  little  fifh 
called  minums,  or  pinks,  throw  themfelves  about  twenty  times 

their 


SECT.  XVI.  15.  i.         OF  INSTINCT.  1 35 

their  own  length  out  of  the  water,  expecting  to  get  into  the 
trough  above. 

This  evinces  that  the  ftorge,  or  attention  of  the  dam  to  pro- 
vide for  the  offspring,  is  ftrongly  exerted  amongft  the  nations 
of  fifti,  where  it  would  feem  to  be  the  moft  negle&ed  ;  as  thefe 
falmon  cannot  be  fuppofed  to  attempt  fo  difficult  and  dangerous 
a  talk  without  being  confcious  of  the  purpofe  or  end  of  their  en- 
deavours. 

It  is  further  remarkable,  that  moft  of  the  old  falmon  return 
to  the  fea  before  it  is  proper  for  the  young  fhoals  to  attend  them, 
yet  that  a  few  old  ones  continue  in  the  rivers  fo  late,  that  they 
become  perfectly  emaciated  by  the  inconvenience  of  their  fitu- 
ation,  and  this  apparently  to  guide  or  to  protect  the  unexperi- 
enced brood. 

Of  the  fmaller  water  animals  we  have  ftill  lefs  knowledge, 
who  neverthelefs  probably  pofTefs  many  fuperior  arts  ;  fome  of 
thefe  are  mentioned  in  Botanic  Garden,  P.  I  Add.  Note  XXVII. 
and  XXVIII.  The  nymphx  of  the  water-moths  of  our  rivers, 
which  cover  themfelves  with  cafes  of  ftraw,  gravel,  and  {hell, 
contrive  to  make  their  habitations  nearly  in  equilibrium  with 
the  water  ;  when  too  heavy,  they  add  a  bit  of  wood  or  ftraw  ; 
when  too  light,  a  bit  of  gravel.  Edinb  Tranf. 

All  thefe  circumftances  bear  a  near  refemblance  to  the  delib- 
erate actions  of  human  reafon. 

XV.  We  have  a  very  imperfect  acquaintance  with  the  vari- 
ous tribes  of  infects  :  their  occupations,  manner  of  life,  and  even 
the  number  of  their  fenfes,  differ  from  our  own,  and  from  each 
other  ;  but  there  is  reafon  to  imagine,  that  thofe  which  pofiefs 
the  fenfe  of  touch  in  the  moft  exquifite  degree,  and  whofe  oc- 
cupations require  the  moft  conftant  exertion  of  their  powers, 
are  endued  with  a  greater  proportion- of  knowledge  and  inge- 
nuity. 

The  fpiders  of  this  country  manufaflure  nets  of  various 
forms,  adapted  to  various  (ituations,  to  arreft  the  flies  that  are 
their  food  ;  and  fome  of  them  have  a  houfe  or  lodging-place  in 
the  middle  of  the  net,  well  contrived  for  warmth,  fecurity,  or 
concealment.  There  is  a  large  fpider  in  South- America,  who 
conftrudls  nets  of  fo  ftrong  a  texture  as  to  entangle  fmall  birds, 
particularly  the  humming  bird.  And  in  Jamaica  there  is  an- 
other fpider,  who  digs  a  hole  in  the  earth  obliquely  downwards, 
about  three  inches  in  length,  and  one  inch  in  diameter  ;  this 
cavity  (he  lines  with  a  tough  thick  web,  which  when  taken  out 
refembles  a  leathern  purfe  ;  but  what  is  moft  curious,  this  houfe 
has  a  door  with  hinges,  like  the  operculum  of  fome  fea  (hells  ; 
and  herfelf  and  family,  who  tenant  this  neft,  open  and  fhut  the 

door, 


OF  INSTINCT.  SECT.  XVI  15.  i. 

door,  whenever  they  pafs  or  repafs.  This  hiftory  was  told  me, 
and  the  neft  with  iis  operculum  (hewn  me  by  the  late  Dr.  Butt 
of  Bath,  who  was  fome  years  phyiician  in  Jamaica. 

The  produftion  of  thefe  nets  is  indeed  a  part  of  the  nature 
or  conformation  of  the  animal,  and  their  natural  ufe  is  to  fup« 
ply  the  place  of  wings,  when  Ihe  wimes  to  remove  to  another 
fituation.  But  when  {he  employs  them  to  entangle  her  prey, 
there  are  marks  of  evident  defign,  for  fhe  adapts  the  form  of 
each  net  to  its  fituation,  and  ftrengthens  thofe  lines,  that  require 
it:,  by  joining  others  to  the  middle  of  them,  and  attaching  thofe 
others  to  diftant  obje£b,  with  the  fame  individual  art,  that  is 
ufed  by  mankind  in  fupporting  the  mafts  and  extending  the 
fails  of  (hips.  This  work  is  executed  with  more  mathematical 
exaftnefs  and  ingenuity  by  the  field  fpiders,  than  by  thofe  in 
our  houfes,  as  their  conftru£Uons  are  more  fubje£led  to  the  in- 
juries of  dews  and  tempeits. 

Befides  the  ingenuity  (hewn  by  thefe  little  creatures  in  taking' 
their  prey,  the  circumftance  of  their  counterfeiting  death,  when 
they  are  put  into  terror,  is  truly  wonderful  j  and  as  foon  as  the 
objeft  of  terror  is  removed,  they  recover  and  run  away.  Some 
beetles  are  alfo  faid  to  poflefs  this  piece  of  hypocrify. 

The  curious  webs,  or  cords,  conftru£led  by  fome  young  cat- 
erpillars to  defend  themfelves  from  cold,  or  from  infers  of  prey 
and  by  filk-worms  and  fome  other  caterpillars,  when  they  tranf- 
migrate  into  aurelixor  larvae,  have  defervedly  excited  the  admi- 
ration of  the  inquifitive.  But  our  ignorance  of  their  manner  of 
life,  and  even  of  the  number  of  their  fenfes,  totally  precludes 
us  from  underftanding  the  means  by  which  they  acquire  this 
knowledge. 

The  care  of  the  falmon  in  choofmg  a  proper  fituation  for  her 
fpawn,  the  ftrudure  of  the  nefts  of  birds,  their  patient  incuba- 
tion, and  the  art  of  the  cuckoo  in  depofiting  her  egg  in  her  neigh- 
bour's nurfery,  are  inftances  of  great  fagacity  in  thofe  creatures  : 
and  yet  they  are  much  inferior  to  the  arts  exerted  by  many  of 
the  infeft  tribes  on  fimilar  occafions.  The  hairy  excrefcences 
on  briars,  the  oak  apples,  the  blafted  leaves  of  trees,  and  the 
lumps  on  the  backs  of  cows  are  fituations  that  are  rather  produ- 
ced than  chofenby  the  mother  infed  for  the  convenience  of  her 
offspring.  The  cells  of  bees,  wafps,  fpiders,  and  of  the  various 
coralline  infects,  equally  aftonifh  us  whether  we  attend  to  the 
materials  or  to  the  architedure. 

But  the  condudl  of  the  ant,  and  of  fome  fpecies  of  the  icji- 
neumon  fly  in  the  incubation  of  their  eggs,  is  equal  to  any  exer- 
tion of  human  fcience  The  ants  many  times  in  a  day  move 
their  eggs  nearer  the  furface  of  their  habitation,  or  deeper  be* 

Jow 


SECT.  XVI.  1 6.  i.          OF  INSTINCT.  137 

low  it,  as  the  heat  of  the  weather  varies ;  and  in  colder  days  lie 
upon  them  in  heaps  for  the  purpoie  of  incubation  :  if  their 
manfion  is  too  dry,  they  carry  them  to  places  where  there  is 
moifture,  and  you  may  diftin  Uy  fee  the  little  worms  move  and 
fuck  up  the  water.  When  too  much  moifture  approaches  their 
neft,  they  convey  their  eggs  deeper  in  the  earth,  or  to  ibme  oth- 
er place  of  fafety.  (Swammerd.  Epil.  ad  Hid.  Infect,  p.  153. 
Phil.  Tranf.  No.  23.  Lowthorp.  V.  2  p.  7.) 

There  is  one  fpecies  of  ichneumon-fly,  that  digs  a  hole  in  the 
earth,  and  carrying  into  it  two  or  three  living  caterpillars,  de- 
pofites  her  eggs,  and  nicely  clofmg  up  the  neft  leaves  them  there  ; 
partly,  doubtlefs,  to  aflift  the  incubation,  and  partly  to  fupply  food 
to  her  future  young,  (Derham.  B.  4.  c.  13.  Ariftotle  Hift. 
Animal.  L.  5.  c.  20  ) 

A  friend  of  mine  put  about  fifty  large  caterpillars  collected 
from  cabbages  on  fome  bran  and  a  few  leaves  into  a  box,  and 
covered  it  with  gauze  to  prevent  their  efcape.  After  a  few 
days  we  faw,  from  more  than  three  fourths  of  them,  about  eight 
or  ten  little  caterpillars  of  the  ichneumon -fly  come  out  of  their 
backs,  and  fpin  each  a  fmall  cocoon  of  filk,  and  in  a  few  days 
the  large  caterpillars  died.  This  fmall  fly  it  feems  lays  its  egg 
in  the  back  of  the  cabbage  caterpillar,  which  when  hatched  preys 
upon  the  material,  which  is  produced  there  for  the  purpofe  of 
making  filk  for  the  future  neit  of  the  cabbage  caterpillar  ;  of 
which  being  deprived,  the  creature,  wanders  about  till  it  dies, 
and  thus  our  gardens  are  preferved  by  the  ingenuity  of  this 
cruel  fly. 

This  curious  property  of  producing  a  filk  thread,  which  is 
common  to  fome  fea  animals,  fee  Botanic  Garden,  Part  I,  Note 
XXVII.  and  is  defigned  for  the  purpofe  of  their  transformation 
as  in  the  iiik-vvorm,  is  ufed  for  conveying  the mfelves  from  higher 
branches  to  lower  ones  of  trees  by  ibme  caterpillars,  and  to  make 
themfelves  temporary  nefts  or  tents,  and  by  the  fpider  for  en- 
tangling his  prey.  Nor  is  it  (trange  that  fo  much  knowledge 
fhould  be  acquired  by  fuch  fmall  animals  j  fince  there  is  reafon 
to  imagine,  that  thefe  infects  have  the  fenfe  of  touch,  either  in 
their  probofcis,  or  their  antennae,  to  a  great  degree  of  perfec- 
tion ;  and  thence  may  poflefs,  as  far  as  their  fphere  extends,  as 
accurate  knowledge,  and  as  fubtle  invention,  as  the  difcoverers 
of  human  arts. 

XVI.  i.  If  we  were  better  acquainted  with  the  hiftories  of 
thofe  infects  that  are  formed  into  focieties,  as  the  bees,  wafps, 
and  ants,  I  make  no  doubt  but  we  mould  find,  that  their  arts 
and  improvements  are  nor  fo  fimilar  and  uniform  as  they  now 
appear  to  us,  but  that  they  rofe  in  the  fame  manner  from  ex- 

VOL.  I.  T  pepence 


1 3 «  OF  INSTINCT.        SECT.  XVI.  1 6.  a. 

perience  and  tradition,  as  the  arts  of  our  own  fpecics  ;  though 
their  reafoning  is  from  fewer  ideas,  is  bufied  about  fewer  ob- 
jeds,  and  is  exerted  with  lefs  energy. 

There  are  fome  kinds  of  infects  that  migrate  like  the  birds 
before  mentioned.  The  locuft  of  warmer  climates  has  fome- 
times  come  over  to  England  ;  it  is  fhaped  like  a  grafshopper, 
with  very  large  wings,  and  a  body  above  an  inch  in  length.  It 
is  mentioned  as  coming  into  Egypt  with  an  eaft  wind,  "  The 
Lord  brought  an  eaft  wind  upon  the  land  all  that  day  and  night, 
and  in  the  morning  the  eaft  wind  brought  the  locufts,  and  cov- 
ered the  face  of  the  earth,  fo  that  the  land  was  dark,"  Exod.  x. 
13.  The  migrations  of  thefe  infedts  are  mentioned  in  another 
parr  of  the  fcripture,  "  The  locufts  have  no  king,  yet  go  they 
forth  all  of  them  in  bands,"  Prov.  xxx.  27. 

The  accurate  Mr.  Adanfon,  near  the  river  Gambia,  in  Africa, 
was  witnefs  to  the  migration  of  thefe  infecls.  "  About  eight  in 
the  morning,  in  the  month  of  February,  there  fuddenly  arofe 
over  our  heads  a  thick  cloud,  which  darkened  the  air,  and  de- 
prived us  of  the  rays  of  the  fun.  We  found  it  was  a  cloud  of 
locufts  raifed  about  twenty  or  thirty  fathoms  from  the  ground, 
and  covering  an  extent  of  ieveral  leagues  ;  at  length  a  fhower  of 
thefe  infecls  defcended,  and  after  devouring  every  green  herb, 
while  they  refted,  again  refumed  their  flight.  This  cloud  was 
brought  by  a  ftrong  eaft  wind,  and  was  all  the  morning  in  pall- 
ing over  the  adjacent  country."  (Voyage  to  Senegal,  158.) 

In  this  country  the  gnats  are  fometimes  feen  to  migrate  in 
clouds,  like  the  mufketoes  of  warmer  climates,  and  our  fwarms 
of  bees  frequently  travel  many  miles,  and  are  faid  in  North 
America  always  to  fly  towards  the  fouth.  The  prophet  Ifaiah  has 
a  beautiful  allufion  to  thefe  migrations,  "  The  Lord  ihall  call 
the  fly  from  the  rivers  of  Egypt,  and  {hall  hifs  for  the  bee  that  is 
in  the  land  of  Aflyria,"  Ifa.  vii.  18.  which  has  been  lately  ex- 
plained by  Mr.  Bruce,  in  his  Travels  to  difcover  the  Source  of 
the  Nile. 

2>  I  am  well  informed  that  the  bees  that  were  carried  into 
Barbadoes,  and  other  werften  iflands,  ceafed  to  lay  up  any  honey 
after  the  iirft  year,  as  they  found  it  not  uieful  to  them  :  and  are 
now  become  very  troublefome  to  the  inhabitants  of  thofe  iflands 
by  infefting  their  fugar-houfes  •,  but  thofe  in  Jamaica  continue 
to  make  honey,  as  the  cold  north  winds,  or  rainy  feafons  of  that 
illand,  confine  them  at  home  for  feveral  weeks  together.  And 
the  bees  of  Senegal,  which  differ  from  thofe  of  Europe  only  in 
flze,  make  their  honey  not  only  fuperiour  to  ours  in  delicacy  of 
flavour,  but  it  has  this  fingularity,  that  it  never  concretes,  but 
remains  liquid  as  fyrup,  (Adanfon).  From  fome  obfervations  of 

Mr. 


SECT.  XVI.  16.  3.          OF  INSTINCT.  139 

Mr.  Wildman,  and  of  other  people  of  veracity,  it  appears,  that 
during  the  fevere  part  of  the  winter  feafon,  for  weeks  together 
the  bees  are  quite  benumbed  and  torpid  from  the  cold,  and  do 
not  confume  any  of  their  provifion.  This  ftate  of  fleep,  like  that 
of  fwallows  and  bats,  feems  to  be  the  natural  refource  of  thofe 
creatures  in  cold  climates,  and  the  making  of  honey  to  be  an 
artificial  improvement. 

As  the  death  of  our  hives  of  bees  appears  to  be  owing  to  their 
being  kept  fo  warm,  as  to  require  food,  when  their  flock  is  cx- 
haufted  ;  a  very  obferving  gentleman  at  my  requefl  put  two 
hives  for  many  weeks  into  a  dry  cellar,  and  obferved  during  all 
that  time;  they  did  not  confume  any  of  their  provifion,  for  their 
weight  did  not  decreafe  as  it  had  done  when  they  were  kept  in 
the  open  air.  The  fame  obfervation  is  made  in  the  Annual 
Regifter  for  1768,  p.  113.  And  the  Rev.  Mr.  White,  in  his 
Method  of  preferving  Bees,  adds,  that  thofe  on  the  north  fid;  of 
his  houfe  confumed  lefs  honey  in  the  winter  than  thofe  on  the 
fouth  fide. 

There  is  another  obfervation  on  bees  well  afcertained,*  that 
they  at  various  times,  when  the  feafon  begins  to  be  cold,  by  a 
general  motion  of  their  legs  as  they  hang  in  cluflers,  produce 
a  degree  of  warmth,  which  is  eafily  perceptible  by  the  hand. 
Hence  by  this  ingenious  exertion,  they  for  a  long  time  prevent 
the  torpid  ftate  they  would  naturally  fall  into 

According  to  the  late  obfervations  of  Mr.  Hunter,  it  appears 
that  the  beeVwax  is  not  made  from  the  duit  of  the  anthers  of 
flowers,  which  they  bring  home  on  their  thighs,  but  that  this 
m  ikes  what  is  termed  bee-bread,  and  is  ufed  for  the  purpofe  of 
feeding  the  bee  maggots  ;  in  the  fame  manner  butterflies  live  on 
hnney,  but  the  previous  caterpillar  lives  on  vegetable  leaves, 
while  the  maggots  of  large  flies  require  flefli  for  their  food,  and 
thofe  of  the  ichneumon  fly  require  infe£ls  for  their  food.  What 
induces  the  bee  who  lives  on  honey  to  lay  up  vegetable  powder 
for  its  young  ?  What  induces  the  butterfly  to  lay  its  eggs  on 
leaves,  when  itfelf  feeds  on  honey  ?  What  induces  the  other  flies 
to  feek  a  food  for  their  progeny  different  from  what  they  con- 
fume  themfelves  ?  If  thefe  are  not  deductions  from  their  own 
previous  experience  or  obfervation,  all  the  actions  of  mankind 
muft  be  refolved  into  inftindl:. 

3.  "  The  dormoufe  confumes  but  little  of  its  food  during  the 
rigour  of  the  feafon,  for  they  roll  themfelves  up,  or  fleep,  or  lie 
torpid  the  greateft  part  of  the  time ;  but  on  warm  funny  days 
experience  a  fhort  revival,  and  take  a  little  food,  and  then  re- 
lapfe  into  their  former  ftate.  (Pennant  Zoolog.  p.  67.)  Other 
animals  that  fleep  in  winter  without  laying  up  any  provender, 

are 


t4*  OF  INSTINCT,  SECT.  XVI.  16. 4, 

are  obferved  to  go  into  their  winter  t>eds  fat  and  ftrong,  but  re- 
turn to  day  light  in  the  fpring  feafon  very  lean  and  feeble.  The 
common  flies  fleep  during  the  winter  without  any  provificn  for 
their  ncurifhrnent,  and  are  daily  revived  by  the  warmth  of  the 
fun,  or  of  our  fires.  Thefe  whenever  they  fee  light  endeavour 
to  approach  it,  having  obferved,  that  by  its  greater  vicinity  they 
get  free  from  the  degree  of  torpor  that  the  cold  produces  ;  and 
are  hence  induced  perpetually  to  burn  themfelves  in  our  candles : 
deceived,  like  mankind,  by  the  mifapplication  of  their  knowl- 
edge. Whilfl  many  of  the  fubterraneous  infecls,  as  the  com- 
mon worms,  feem  to  retreat  fo  deep  into  the  earth  as  not  to  be 
enlivened  or  awakened  by  the  difference  of  our  winter  days ; 
and  flop  up  their  holes  with  leaves  or  ftraws,  to  prevent  the 
frofls  from  injuring  them,  or  the  centipes  from  devouring  them* 
The  habits  of  peace,  or  the  flratagems  of  war,  of  thefe  fubterra- 
nean  nations  are  covered  from  our  view  ;  but  a  friend  of  mine 
prevailed  on  a  diftreffed  worm  to  enter  the  hole  of  another  worm 
on  a  bowling-green,  and  he  prefently  returned  much  wounded 
about  his  head.  And  I  once  faw  a  worm  rife  haflily  out  of  the 
earth  into  the  fun-fhine,  and  obferved  a  centipes  hanging  at  its 
tail :  the  centipes  nimbly  quitted  the  tail,  and  feizing  the  worm 
about  irs  middle,  cut  it  in  half  with  its  forceps,  and  preyed  upon 
one  part,  while  the  other  efcaped.  Which  evinces  they  have 
defign  in  flopping  the  mouths  of  their  habitations. 

4.  The  wafp  of  this  country  fixes  his  habitation  under  ground, 
that  he  may  not  be  affecled  with  the  various  changes  of  our 
climate ;  but  in  Jamaica  he  hangs  it  on  the  bough  of  a  tree, 
where  the  feafon s  are  lefs  fevere.  He  weaves  a  very  curious 
paper  of  vegetable  fibres  to  cover  his  nefl,  which  is  conftrucled 
on  the  lame  principle  with  that  of  the  bee,  but  with  a  different 
material ;  but  as  his  prey  confifts  of  flefh,  fruits,  and  iniedb, 
which  are  perifhable  commodities,  he  can  lay  up  no  provender 
for  the  winter. 

M.  de  la  Loubiere,  in  his  relation  of  Siam,  fays,  «  That  in  a 
part  of  that  kingdom,  which  lies  open  to  great  inundations,  all 
the  ants  make  their  fettlemenrs  upon  trees  ;  no  ants'  nefts  are  to 
be  feen  any  where  elfe."  Whereas  in  our  country  the  ground 
is  their  only  fituation.  From  the  icriptural  account  of  thefe  in- 
fects, one  might  be  led  to  fufpedl,  thatinfome  climates  they  lay 
up  a  provifion  for  the  winter,  (Prov.  vi.  6.  xxx.  25-)  Origen  af- 
firms the  fame,  (Com,  Celf.  L.  4.)  But  it  is  generally  believed 
thar  in  this  country  they  do  not.  The  white  ants  of  the  coait 
of  Africa  make  themfelves  pyramids  eight  or  ten  feet  high,  on 
a  bafe  of  about  the  iame  width,  with  a  fmooth  furface  of  rich 
clay,  exceffively  hard  and  well  built,  which  appear  at  a  diftance 


SECT.  XVI.  17.1.          OF  INSTINCT.  1 4 1 

like  an  aflemblage  of  the  huts  of  the  negroes,  ( Adanfon).  The 
hiftory  of  thefe  has  been  lately  well  defcribed  in  the  Philofoph. 
f  ranfa&ions,  under  the  name  of  termes,  or  termites,  Thefe 
differ  very  much  from  the  neft  of  our  large  ant  ;  but  the  real 
hiitory  of  this  creature,  as  well  as  of  the  wafp,  is  yet  very  im- 
perfectly known. 

Wafps  are  faid  to  catch  large  fpiders,  and  to  cut  off  their  legs* 
and  carry  their  mutilated  bodies  to  their  young,  Did:.  Raifon. 
Tom.  I.  p.  152. 

One  circumftance  I  (hall  relate  which  fell  under  my  own  eye, 
and  (hewed  the  power  of  reafon  in  a  wafp,  as  it  is  exercifed 
among  men.  A  wafp,  on  a  gravel  walk,  had  caught  a  fly  nearly 
as  large  as  himfelf  ;  kneeling  on  the  ground  I  obferved  him  fep- 
arate  the  tail  and  the  head  from  the  body  part,  to  which  the 
wings  were  attached.  He  then  took  the  body  part  in  his 
paws,  and  rofe  about  two  feet  from  the  ground  with  it ;  but  a 
gentle  breeze  wafting  the  wings  of  the  fly  turned  him  round  in 
the  air,  and  he  fettled  again  with  his  prey  upon  the  gravel.  I 
then  diftindly  obferved  him  cut  off  with  his  mourh,  firft  one  of 
the  wings,  and  then  the  other,  after  which  he  flew  away  with 
it  unmolefted  by  the  wind. 

Go,  thou  fluggard,  learn  arts  and  induftry  from  the  bee,  and 
from  the  ant  ! 

Go,  proud  reafoner,  and  call  the  worm  thy  fifter  ! 

XVII.     Conclufion, 

It  was  before  obferved  how  much  the  fuperior  accuracy  of 
our  ienieof  touch  contributes  to  increafe  our  knowledge  ;  but 
it  is  the  greater  energy  and  activity  of  the  power  of  volition  (as 
explained  in  the  former  Sections  of  this  work)  that  marks  man* 
and  has  given  him  the  empire  of  the  world. 

1  here  is  a  criterion  by  which  we  may  diftinguifh  our  volun- 
tary acts  or  thoughts  from  thofe  that  are  excited  by  our  fenfa- 
tions  j  «<  The  former  are  always  employed  about  the  means  to 
acquire  pleafurable  objects,  or  to  avoid  painful  ones  :  while  the 
latter  are  employed  about  the  poffejflon  of  thofe  that  are  already 
in  our  power." 

If  we  turn  our  eyes  upon  the  fabric  of  our  fellow  animals, 
we  find  they  are  fupported  with  bones, covered  withfkins,  moved 
by  mufcles  ;  that  they  poffefs  the  fame  fenfes,  acknowledge  the 
fame  appetites,  and  are  nourifhed  by  the  fame  aliment  with  our- 
felves  ;  and  we  fhould  hence  conclude  from  the  ftrongeft  anal- 
ogy, that  their  internal  faculties  were  alfo  infome  meafure  fun- 
ilar  to  our  own. 

Mr. 


i42  OF  INSTINCT.  SECT.  XVI.  17.  i. 

Mr.  Locke  indeed  published  an  opinion,  that  other  animals 
poflefled  no  abftraft  or  general  ideas,  and  thought  this  circum- 
ftance  was  the  barrier  between  the  brute  and  the  human  world. 
But  thefe  abftra&ed  ideas  have  been  fince  demonflrated  by  bifh- 
op  Berkeley,  and  allowed  by  Mr,  Hume,  to  have  no  exiftence  in 
nature,  not  even  in  the  mind  of  their  inventor,  and  we  are 
hence  neceflitated  to  look  for  fome  other  mark  of  diftinftion. 

The  ideas  and  aftions  of  brutes,  like  thofe  of  children,  are 
almoft  perpetually  produced  by  their  prefent  pleafures,  or  their 
prefent  pains  ;  and,  except  in  the  few  in  (lances  that  have  been 
mentioned  in  this  Section,  they  feldom  bufy  themfelves  about 
the  means  of  procuring  future  blifs,  or  avoiding  future  mifery. 

Whilft  the  acquiring  of  languages,  the  making  of  tools,  and 
the  labouring  for  money  ;  which  are  all  only  the  means  of  pro- 
curing pleafure  ;  and  the  praying  to  the  Deity,  as  another  means 
to  procure  happinefs,  are  charadleriftic  of  human  nature. 


SECT, 


SECT.  XVII.  i.  i.      CATENATION,  &c,  143 

SECT.      XVII. 

THE    CATENATION   OF    MOTIONS. 

I.  I.  Catenations  of  animal  motion*  2.  Are  produced  by  irritations, 
by  fenfation s  ^  by  'volitions.  3.  They  continue  fometime  after  they 
have  been  excited  Caufe  of  catenation.  4.  We  can  then  exert 
our  attention  on  other  objects.  5.  Many  catenations  of  motions  go 
on  together.  6.  Some  links  of  the  catenations  of  motions  may  be 
left  without  dif uniting  the  chain.  7.  Interrupted  circles  of  mo- 
tion continue  confufedly  till  they  come  to  the  part  oj  the  circle ^ 
•where  they  were  dijlurbed.  8  Weaker  catenations  are  diffever- 
ed  byftronger.  9.  Then  new  catenations  take  place.  10.  Much 
effort  prevents  their  re-uniting.  Impediment  of  fpeech.  1 1,  Trains 
more  enfily  dijjevered  than  circles.  12.  Sleep  dejlroys  volition  and 
external  Jlimulus.  II.  Inftances  of  various  catenations  in  a  young 
lady  playing  on  a  harpfichord.  Ill  I.  What  catenations  are 
theftrongeft.  2.  Irritations  joined  with  ajffbciations  form  Jlrong- 
eft  connexions.  Vital  motions.  3.  New  links  with  increafed 
jorcey  cold  Jits  of ftver  produced.  4.  New  links  with  decreafed 
force.  Co  id  bath  5.  Irritation  joined  with  fenfation.  Inflam- 
matory fever.  Why  children  cannot  tickle  themf elves.  6.  Voli- 
tion joined  with  fenfation.  Irritative  ideas  of  found  be  come  f*nfi- 
ble.  7.  Ideas  of  imagination  dijjevered  by  irritations^  by  volition^ 
production  offurprife. 

1.  i.  To  inveftigate  with  precifion  the  catenations  of  animal 
motions,  it  would  be  well  to  attend  to  the  manner  of  their  pro- 
duction ;  but  we  cannot  begin  this  difquifition  early  enough  for 
this  purpofe,  as  the  catenations  of  motion   feem  to  begin  with 
life,  and  are  only   extinguifhable  with  it.     We  have  fpoken  of 
the  power  of  irritation,  of  fenfation,  of  volition,  and  of  aflbcia- 
tion,  as  preceding  the  fibrous  motions  ;  we  now  ftep  forwards, 
and  confider,  that  converleiy  they  are  in  their  turn  preceded  by 
thofe  motions  ;  and  that  all  the  fucceffive  trains  or  circles  of  our 
adUons  are  compoied  of  this  twofold  concatenation.     Thofe  we 
(hall  call  trains   of  a£lion,  which  continue  to  proceed  without 
any  dated  repetitions  ;  and   thofe  circles  of  action,  when  the 
parts  of  them  return  at   certain    periods,  though  the  trains,  of 
which  they  confift,    are    not  exactly  fimilar.     The  reading  an 
epic  poem  is  a  train  of  actions  ;  the   reading  a  fong  with  a  cho- 
rus at  equal  diftances  in  the  meafure  conftitutes  fo  many  circles 
of  action. 

2.  Some  catenations  of  animal  motion  are  produced  by  reiter- 

ated 


*44  CATENATION.  SECT.  XVII.  I(  3, 

ated  fucceffive  irritations,  as  when  we  Jearn  to  repeat  the  alpha- 
bet in  its  order  by  frequently  reading  the  letters  of  it.  Thus  the 
vermicular  motions  of  the  bowels  were  originally  produced  by 
the  fucceifive  irritations  of  rhe  paffmg  aliment  ;  and  the  fuccef- 
fion  of  actions  of  the  auricles  and  ventricles  of  the  heart  was 
originally  formed  by  fucceffive  ftimulus  of  the  blood,  thefe  after- 
wards become  part  of  the  diurnal  circles  of  animal  actions,  as 
appears  by  the  periodical  returns  of  hunger,  and  the  quickened 
pulfe  of  weak  people  in  the  evening 

Other  catenations  of  aniiral  motion  are  gradually  acquired 
by  fucceffive  agreeable  fenfations,  as  in  learning  a  favourite  fong 
or  dance  ;  others  by  difagreeable  fenfations,  as  in  coughing  or 
nictitation  ;  thefe  become  affociated  by  frequent  repetition,  and 
afterwards  compofe  parts  of  greater  circles  of  action  like  thofe 
above  mentioned. 

Other  catenations  of  motions  are  gradually  acquired  by  fre- 
quent voluntary  repetitions  ;  as  when  we  deliberately  learn  to 
march,  read,  fence,  or  any  mechanic  art,  the  motions  of  many 
of  our  mufcles  become  gradually  linked  together  in  trains,  tribes, 
or  circles  of  action.  Thus  when  any  one  at  firft  begins  to  ufe 
the  tools  in  turning  wood  or  metals  in  a  lathe,  he  wills  the  mo- 
tions of  his  hand  or  fingers,  till  at  length  thefe  actions  become 
ib  connected  with  the  effect,  that  he  feems  only  to  will  the 
point  of.  the  chiffel.  Thefe  are  caufed  by  volition,  connected 
by  affociation  like  thofe  above  defcribed,  and  afterwards  become 
parts  of  our  diurnal  trains  or  circles  of  action. 

3.  All  thefe  catenations  of  animal  motions  are  liable  to  pro- 
ceed fome  time  after  they  are  excited,  unlefs  they  are  difturbed 
or  impeded    by  other  irritations,  fenfations,  or  volitions  5  and 
in  many  inftances  in  fpite  of  our  endeavours  to  flop  them  ;   and 
this  property  of  animal  motions  is  probably  the  caufe  of  their 
catenation.     Thus  when  a  child  revolves  fome  minutes  on  one 
foot,  the  fpeftra  of  the  ambient  objects  appear  to  circulate  round 
him  fome  time  after  he  falls  upon  the  ground.     Thus  the  pal- 
pitation of  the  heart  continues  fome  time  after  the  object  of  fear, 
which  ocafioned  it,  is  removed.     The  blufh  of  fhame,  which  is 
an  excefs  of  ienfation,  and  the  glow  of  anger,  which  is  an  excefs 
of  volition,  continue  fome  time,  though  the  affected  perlon  finds 
that  thofe  emotions  were  caufed  by  miftaken  facts,  and  endeav- 
ours to  extingiulh  their  appearance.     See  Sect.  XII.  1.5, 

4.  When  a  circle  of  motions  becomes  connected  by  frequent 
repetitions  as  above,  we  can  exert  our  attention  ftrongly  on  oth- 
er objects,  and  the  concatenated  circle  of  motions  will  neverthe- 
kfs  proceed  in  diie   order  ;  as  whilft  you    are  thinking  on  this 

fubject 


SECT.  XVII.  i.  5.          OF  MOTIONS.  145 

fubject,  you  ufe  variety  of  mufcles  in  walking  about  your  parlour, 
or  in  fitting  at  your  writing-table. 

5.  Innumerable  catenations  of  motions  may  proceed  at  the 
fame   time,  without  incommoding  each  other.     Of  thefe  are 
the  motions  of  the  heart  and  arteries  ;  thofe  of  digeition  and 
glandular  fecretion  ;  of  the  ideas,  or  fenfual  motions  ;  thofe  of 
progreflion,  and  of  fpeaking *,  the  great  annual  circle  of  actions 
fo  apparent  in  birds  in  their  times  of  breeding  and  moulting  ; 
the  monthly  circles  of  many  female  animals ;  and  the  diurnal 
circles  of  fleeping  and  waking,  of  fulaefs  and  inanition. 

6.  Some  links  of  fucceflive  trains  or  of  fynchronous  tribes  of 
a&ion  may  be  left  out  without  disjoining  the  whole.     Such  are 
our  ufual  trains  of  recollection  :  after  having  travelled  through 
an  entertaining   country,   and  viewed  many  delightful  lawns, 
rolling  rivers,  and  echoing  rocks  ;  in  the  recollection  of  our 
journey  we  leave  out  the  many  diftricts,  that  we  crofied,  which 
were  marked  with  no  peculiar  pleafure.     Such  alfo  are  our  com- 
plex ideas,  they  are  catenated  tribes  of  ideas,  which  do  not  per- 
fectly refemble  their  correfpondent  perceptions,  becaufe  fome  of 
the  parts  are  omitted. 

7.  If  an  interrupted  circle  of  actions  is  not  entirely  difievered, 
it  will  continue  to  proceed  confufedly,  till  it  comes  to  the  part 
of  the  circle,  where  it  was  interrupted. 

The  vital  motions  in  a  fever  from  drunkennefs,  and  in  other 
periodical  difeafes,  are  inftances  of  this  circum  (lance.  The  ac- 
cidental inebriate  does  not  recover  himfelf  perfectly  till  about 
the  fame  hour  on  the  fucceeding  day.  The  accuftomed  drunk- 
ard is  difordered  if  he  has  not  his  ufual  potation  of  ferment- 
ed liquor.  So  if  a  confiderable  part  of  a  connected  tribe  of  ac- 
tion be  difturbed,  that  whole  tribe  goes  on  with  confufion,  till 
the  part  of  the  tribe  affected  regains  its  accuftomed  catenations. 
So  vertigo  produces  vomiting,  and  a  great  fecretion  of  bile,  as 
in  fea-ficknefs,  all  thefe  being  parts  of  the  tribe  of  irritative  cat- 
enations. 

8.  Weaker  catenated  trains  may  be  diflevered  by  the  fudden 
exertion  of  the  ftronger.     When  a  child  firft  attempts  to  walk 
acrofs  a  room,  call  to  him,  and  he  inftantly  falls  upon  the  ground. 
So  while  I  am  thinking  over  the  virtues  of  my  friend,   if  the 
tea-kettle  fpurt  out  fome  hot  water  on  my  flocking  ;    the  fudden 
pain  breaks  the  weaker  chain  of  ideas,  and  introduces  a  new 
group  of  figures  of  its  own      This  circumftance  is  extended  to 
fome  unnatural  trains  of  action,  which  have  not  been  confirmed 
by  long  habit ;   as  the  hiccough,  or  an  ague-fit,  which  are  fre- 
quently curable  by  furprife.    A  young  lady  about  eleven  years  old 
had  for  five  days  had  a,  contraction  of  one  mufcle  in  her  fore  arm, 

VOL.  I.  U  and 


i46  CATENATION         SECT.  XVII.  i.  9 

and  another  in  her  arm,  which  occurred  four  or  five  times  every 
minute  ;  the  mufcles  were  feen  to  leap,  but  without  bending  the 
arm.  fo  counteract  this  new  morbid  habit,  an  iilue  was  placed 
over  the  convul  ed  mufcle  of  her  arm,  and  an  adhefive  plaitei? 
wrapped  tight  like  a  bandage  over  the  whole  fore  arm,  by  which 
the  new  motions  were  immediately  deftroyed,  but  the  means 
were  continued  fame  weeks  to  prevent  a  return. 

y.  If  any  circle  of  actions  is  diifcveredv  either  by  omiflion  of 
fome  of  the  links,  as  in  fleep,  or  by  iniertion  of  other  links,  as 
in  furprife,  new  catenations  take  place  in  a  greater  or  lefs  degree. 
The  laft  link  of  the  broken  chain  of  actions  becomes  connected 
with  the  new  motions  which  has  broken  it,  or  with  that  which 
was  neareft  the  link  omitted  ;  and  thefe  new  catenations  pro- 
ceed inftead  of  the  old  ones.  Hence  the  periodic  returns  of 
ague-fits,  and  the  chimeras  of  our  dreams. 

10.  If  a  train  of  a&ions  is  dhTevered,  much  effort  of  volition 
or  fenfation  will  prevent  its  being  reftored.     Thus  in  the  com- 
mon impediment  of  fpeech,  when  the  affociation  of  the  motions 
of  the  mufcles  of  enunciation  with  the  idea  of  the  word  to  be 
fpoken  is  difordered,  the  great  voluntary  efforts,  which  diftort 
the  countenance,    prevent  the  rejoining  of  the  broken   aflbcia- 
tions.     hee  No.  II    i  o.  of  this  Section.     It  is  thus  hkewife  ob- 
fervable  in  fome  inflammations  of  the  bowels,  the  too  ftrong  ef- 
forts made  by  the  mufcles  to  carry  forwards  the  offending  ma- 
terial fixes  it  more  firmly  in  its  place,  and  prevents  the  cure.    So 
in  endeavouring  to  recal  to  our  memory  fome  particular  word 
of  a  fentence,  if  we  exert  ourfelves  too  flrongly  about  it,  we  are 
lefs  likely  to  regain  it. 

1 1.  Catenated  trains  or  tribes  of  action  are  eafier  diflevered 
than  catenated  circles  of  action.     Hence  in  epileptic  fits  the 
fynchronous  connected  tribes  of  action,    which  keep  the   body 
erect,  are  diflevered,  but  the  circle  of  vital  motions  continues 
undifturbed. 

12  S!?ep  deftroys  the  power  of  volition,  and  precludes  the 
ftimuli  of  external  objects,  and  thence  diffevers  the  trains,  of 
which  thefe  are  a  part  -9  which  confirms  the  other  catenations, 
as  thofe  of  the  vital  motions,  fecretions,  and  abforptions  ;  and 
produces  the  new  trains  of  ideas,  which  conflitute  our  dreams. 

II.  i.  All  the  preceding  circumilances  of  the  catenations  of 
animal  motions  will  be  more  clearly  underftood  by  the  follow- 
ing example  of  a  perfon  learning  mufic  :  and  when  we  recollect 
the  variety  of  mechanic  arts,  which  are  performed  by  aflbciated 
trains  of  mufcular  actions  catenated  with  the  effects  they  pro- 
duce, as  in  knitting,  netting,  weaving  ^  and  the  greater  variety 
of  aflociated  trains  of  ideas  caufed,  or  catenated  by  volitions  or 

fenfations. 


SECT.  XVII.  a.  2.          OF  MOTIONS.  147 

fenfations,  as  in  our  hourly  modes  of  reafoning,  or  imagining, 
or  recollecting,  we  (hall  gain  fome  idea  of  the  innumerable  cat- 
enated trains  and  circles  of  action,  which  form  the  tenor  of  our 
lives,  and  which  began,  and  will  only  ceafe  entirely  with  them. 

2.  When  a  young  lady  begins  to  learn  mufic,  (he  voluntarily 
applies  herfelf  to  the  characters  of  her  mufic-book,  and  by  many 
repetitions  endeavours  to  catenate  them  with  the  proportions  of 
found,  of  which  they  are  fymbols.     The  ideas  excited  by  the 
mufical  characters  are  ilowly  connected  with  the  keys  of  the 
harpfichord,  and  much  effort  is  neceiTary  to  produce  every  note 
with  the  proper  finger,    and  in  its  due  place  and  time  •,    till  at 
length   a  train  of  voluntary  exertions  becomes  catenated   with 
certain  irritations.     As  the  various  notes  by  frequent  repetitions 
become  conne&ed  in  the  order,  in   which  they  are  produced,  a 
new  catenation  of  fenfitive  exertions  becomes  mixed   with   the 
voluntary  ones  above  defcribed;  and  not  only  the  mufical  fym- 
bols of  crotchets  and  quavers,  but  the  auditory  notes  and  tones 
at  the   fame  time,  become  fo  many  fucceffive  or   fynchronous 
links  in  this  circle  of  catenated  actions. 

At  length  the  motions  of  her  fingers  become  catenated  with 
the  mufical  characters ;  and  thefe  no  fooner  ftrike  the  eye,  than 
the  finger  prefies  down  the  key  without  any  voluntary  artention 
between  them  ;  the  activity  of  the  hand  being  connected  with 
the  irritation  of  the  figure  or  place  of  the  mufical  fymbcl  on  the 
retina  ;  till  at  length  by  frequent  repetitions  of  tht  fame  rune  the 
movements  of  her  fingers  in  playing,  and  the  mircles  of  the 
larynx  in  finging,  become  aflbciated  with  each  other,  arid  form 
part  of  thofe  intricate  trains  and  circles  of  catenated  morions, 
according  with  the  fecond  article  of  the  preceding  propofmons 
in  No.  i.  of  this  Section. 

3.  Befides  the  facility,  which  by  habit  attends  the  execution 
of  this  mufical  performance,  a   curious  circumftance  occurs, 
which  is,  that  when  our  young  mufician  has  begun  a  tune,  (he 
finds  herfelf  inclined  to  continue  it ;  and  that  even  when  fhe  is 
carelefsly  finging  alone  without  attending  to  her  own   fong  j 
according  with  the  third  preceding  article 

4.  At  the  fame  time  that  our  young  performer  continues  to 
play  with  great  exactneis  this  accuftomed  tune,    (he  can  bend 
her  mind,  and  that  intensely,  on  fome  other   object,   according 
with  the  fourth  article  of  the  preceding  propofitions. 

The  manufcript  copy  of  this  work  was  lent  to  many  of  my 
friends  at  different  times  for  the  purpofe  of  gaining  their  opin- 
ions and  criticifrns  on  many  parts  of  it,  and  I  found  the  follow- 
ing  anecdote  written  with  a  pencil  oppofire  to  this  page,  but  am 
not  certain  by  whom.  «  I  remember  feeing  the  pretty  young 

aclrefs, 


i-48  CATENATION          SECT.  XVII.  2. 5. 

aftrefs  who  fuceeded  Mrs.  Arne  in  the  performance  of  the 
celebrated  Padlock,  rehearfe  the  mufical  parts  at  her  harpfichord 
under  the  eye  of  her  matter  with  great  taite  and  accuracy  ; 
though  I  obferved  her  countenance  full  of  emotion,  which  I 
could  not  account  for  ;  at  laft  (he  fuddenly  burft  into  tears  ;  for 
{he  had  all  this  time  been  eying  a  beloved  canary  bird,  fuffer- 
ing  great  agonies,  which  at  that  inftant  fell  dead  from  its  perch." 

5.  At  the  fame  time   many  other  catenated  circles  of  action 
are  going  on  in    the  perfon  of  our  fair  mufician,  as  well  as  the 
motions  of  her  fingers,  fuch  as  the  vital  motions,  refpiration,  the 
movements  of  her  eyes  and  eyelids,  and  of  the  intricate  mufcles 
of  vocality,  according  with  the  fifth  preceding  article. 

6.  If  by  any  ftrong  impreffion  on  the  mind  of  our  fair  rnufi- 
cian  (he  fhould  be  interrupted  for  a  very  inconfiderable  time,  fhe 
can  ftill  continue  her  performance,  according  to  the  fixth  article. 

7.  If  however  this  interruption  be  greater,  though  the  chain 
of  aclions   be    not  diflevered,  it  proceeds  confufedly,  and  our 
young  performer  continues  indeed  to  play,  but  in  a  hurry  with- 
out accuracy  and  elegance,  till  fhe  begins  the  tune  again,  accord- 
ing to  the  feventh  of  the  preceding  articles. 

8.  But  if  this   interruption  be  ftill  greater,  the  circle  of  ac- 
tions becomes  entirely  diflevered,  and  fhe  finds  herfelf  immedi- 
ately under  the    neceflity  to  begin  over  again  to  recover  the  loft 
catenation,  according  to  the  eighth  preceding  article. 

9  Or  in  trying  to  recover  it  fhe  will  fing  fome  diflbnant  notes, 
or  ftrike  fome  improper  keys,  according  to  the  ninth  preceding 
article. 

10.  A  very  remarkable  thing  attends  this  breach  of  catena- 
tion, if  the  performer  has  forgotten  fome  word  of  her  fong,  the 
more  energy  of  mind  fhe  ufes  about  it,  the  more  diftant  is  fhe 
from  regaining  it  j  and  artfully  employs  her  mind  in  part  on 
fome  other  object,  or  endeavours  to  dull  its  perceptions,  contin- 
uing to  repeat  as  it  were  inconfcioufly,  the  former  part  of  the 
long,  that  fhe  remembers,  in  hopes  to  regain  the  loft  connexion. 

For  if  the  activity  of  the  mind  itfelf  be  more  energetic,  or 
taket  its  attention  more,  than  the  conne&ing  word,  which  is 
wanted  ;  it  will  not  perceive  the  flighter  link  of  this  loft  wordj 
as  who  liftens  to  a  feeble  found,  mult  be  very  filent  and  mo- 
tionlefs  9  fo  that  in  this  cafe  the  very  vigour  of  the  mind  itfelf 
feems  to  prevent  it  from  regaining  the  Jolt  catenation,  as  well  as 
the  too  great  exertion  in  endeavouring  to  regain  it,  according  to 
the  tenth  preceding  article- 

We  frequently  experience,  when  we  are  doubtful  about  the 
fpelling  of  a  word,  that  the  greater  voluntary  exertion  we  ufe, 
that  is,  ihe  more  imenfdy  we  think  about  it,  the  further  are  we 

from, 


SECT.  XVII.  2.  1 1,        OF  MOTIONS.  149 

from  regaining  the  loft  aflbciation  between  the  letters  of  it,  but 
which  readily  recurs  when  we  have  become  carelefs  about  it.  In 
the  fame  manner,  after  having,  for  an  hour  laboured  to  recollect 
the  name  of  fome  abfent  perfon,  it  {hall  feem,  particularly  after 
fleep,  to  come  into  the  mind  as  it  were  fpontaneoufly  ;  that  is, 
the  word  we  are  in  fearch  of,  was  joined  to  the  preceding  one 
by  aflbciation  ;  this  aflbciation  being  diflevered,  we  endeavour 
to  recover  it  by  volition  ;  this  very  adlion  of  the  mind  ftrikes 
our  attention  more,  than  the  faint  link  of  aflbciation,  and  we 
find  it  impoflible  by  this  means  to  retrieve  the  loft  word.  After 
fleep,  when  volition  is  entirely  fufpended,  the  mind  becomes 
capable  of  perceiving  the  fainter  link  of  aflbciation,  and  the  word 
is  regained. 

On  this  circumftance  depends  the  impediment  of  fpeech  be- 
fore mentioned  ;  the  firft  Syllable  of  a  word  is  caufable  by  vo- 
lition, but  the  remainder  of  it  is  in  common  converfation  intro- 
duced by  its  aflbciations  with  this  firft  fyllable  acquired  by  long 
habit.  Hence  when  the  mind  of  the  ftammerer  is  vehemently 
employed  on  fome  idea  of  ambition  of  fhining,  or  fear  of  not 
fucceeding,  the  aflbciations  of  the  motions  of  the  mufcles  of  ar- 
ticulation with  each  other  become  diflevered  by  this  greater  ex- 
ertion, and  he  endeavours  in  vain  by  voluntary  efforts  to  rejoia 
the  broken  aflbciation.  For  this  purpofe  he  continues  to  re- 
peat the  firft  fyllable,  which  is  caufable  by  volition,  and  drives 
in  vain,  by  various  diftortions  of  countenance,  to  produce  the 
next  links,  which  are  fubjecl;  to  aflbciation.  See  Clafs  IV.  3.1.1. 

1 1.  After  our  accomplished    mufician  has  acquired  great  va- 
riety of  tunes  and  fongs,  fo  that  fome  of  them  begin  to  ceafe  to 
be  eafily  recollected,   (he    finds   progreflive    trains   of  muficai 
notes  more   frequently  forgotten,  than  thofe  which  are  compo- 
fed  of  reiterated  circles,  according   with  the  eleventh  preceding 
article. 

12.  To  finiih  our   example  with  the  preceding    articles  we 
muft  at  length  fuppofe,  that  our  fair  performer  falls  afleep  over 
her  harpfichord  j  and  thus  by  fufpenfion  of  volition,  and  the  ex- 
clufion  of  external  ftimuli,  (he  diflevers  the  trains  and  circles  of 
her  muficai  exertions. 

III.  i.  Many  of  thefe  circumftances  of  catenations  of  mo- 
tions receive  an  eafy  explanation  from  the  four  following  confe- 
quences  to  the  feventh  law  of  animal  caufation  in  Sect.  IV. 
Thefe  are,  firit,  that  thofe  fucceflions  or  combinations  of  animal 
motions,  whether  they  were  united  by  caufation,  aflbciation,  or 
catenation,  which  have  been  moft  frequently  repeated,  acquire 
the  ftrongefi  connexion.  Secondly,  that  of  thefe,  thofe,  which 
have  been  lefs  frequently  mixed  with  other  trains  or  tribes  of 

motion, 


150  CATENATION  SECT.  XVIL  3.  2. 

motion,  have  the  ftrongeft  connexion.  Thirdly,  that  of  thefe, 
thofe,  which  were  firft  formed,  have  the  (trongeft  connexion. 
Fourthly,  that  if  an  animal  motion  be  excited  by  more  than  one 
caufation,  affbciation,  or  catenation,  at  the  fame  time,  it  will  be 
performed  with  greater  energy. 

2.  Hence  alfo  we  understand,  why  the  catenations  of  irrita- 
tive motions  are  more  ilrongly  connected  than  thofe  of  the  oth- 
er claftes,  where    the    quantity  of  unmixed  repetition  has  been 
equal  ;  becaufe  thry   were  firft  formed.     Such  are  thofe  of  the 
fecerning  and  abforbent  fyftems  of  veiTels,  where  the  action  of 
the  gland  produces  a  fluid,  which    ftimulates  the  mouths  of  its 
correipondent  abforbents.     The  afTociated  motions  feem  to  be 
the  next  moft  ftrongly   united,  from  their  frequent  repetition  ; 
and  where  both  thefe  circumftances  unite,  as  in  the  vital  motions, 
their  catenations   are  indiiloluble  but  by  the  deftru£tion  of  the 
animal. 

3.  Where  a   new  link  has  been  introduced  into  a  circle  of 
a£hons  by  fome  accidental  defeft  of  ftimulus  ;  if  that  defeft  of 
ilimulus  be  repeated   at    the  fame  part  of  the  circle  a  fecond  or 
a  third  time,  the  defective  motions  thus  produced,  both  by  the 
repeated  defe£t  of   ftimulus  and  by  their  catenation  with  the 
parts  of  the  circle   of  actions,  will  be  performed  with  lefs  and 
lefs  energy.     Thus  if  any  perfon  is  expofed  to  cold  at  a  certain 
hour  to-day,  fo  long  as  to  render  fome  part  of  the  fyftem  for 
a  time  torpid  ;  and  is   again   expofed  to  it  at  the  fame  hour  to- 
morrow, and  the  next  day  ;  he  will  be  more  and  more  afTe&ed 
by  it,  till  at  length  a  cold  fit  of  fever  is  completely  formed,  as 
happens  at  the  begining  of    many  of  thofe  fevers,  which  are 
called  nervous -or  low  fevers.     Where  the  patient  has  flight  pe- 
riodical fhiverings  and  palenefs  for  many  days  before  the  febrile 
paroxyfm  is  completely  formed. 

4.  On  the  contrary  if  the  expofure  to  cold  be  for  fo  fhort  a 
time,  as  not  to  induce  any  confiderable  degree  of  torpor  or  qui- 
efcence,  and  is  repeated  daily  as  above  mentioned,  it  lofes  its 
effeft  more  and  more  at  every  reperirion,  till  the  conftitution 
can  bear  it  without  inconvenience,  or  indeed  without  being  con- 
fcious  of  it.     "As  in  walking  into    the  cold  air  in  froity  weather. 
The  fame  rule  is  applicable  to   increafed  ftimulus,  as  of  heat,  or 
vinous  fpirit,  within  certain  limits,  as  is  applied  in  the  two  lad 
paragraphs  to  Deficient  Stimulus,  as  is  further  explained  in  Seft. 
XXXVI.  on  the  Periods  of  Difeafes. 

5.  Where  irritation   coincides  with  fenfation  to  produce  the 
fame  catenations  of  motion,  as  in  inflammatory  fevers,  they  are 
excited  with  ftill  greater  energy  than  .by  the  irritation  alone. 
So  when  children  expert  to  be  tickled  in  play,  by  a  feather  light- 


SECT.  XVII.  3. 6.  OF  MOTIONS.  151 

ly  pafled  over  the  lips,  or  by  gently  vellicating  the  foles  of  their 
feet,  laughter  is  mod  vehemently  excited  ;  though  they  can 
ftimulate  thefe  parts  with  their  own  fingers  unmoved'.  Here 
the  pleafurable  idea  of  playfulnefs  coincides  with  the  vellication  ; 
and  there  is  no  voluntary  exertion  ufed  to  dimimfh  the  fenfa- 
tion,  as  there  would  be,  if  a  child  mould  endeavour  to  tickle 
himfelf.  See  Sett  XXXIV.  i.  4. 

6.  And  laftly  the  motions   excited  by  the  junftion  of  volun- 
tary exertion  with   irritation  are   performed  with   more  energy, 
than  thofe  by   irritation  fingly  ;  as    when    we    liften  to  fmall 
noiles,  as  to  the  ticking   of  a  watch    in    the  night,  we  perceive 
the  mod  weak    founds,   that  are   at  other  times  unheeded.     So 
when  we  attend  to  the    irritative   ideas   of  found  in  our  ears, 
which  are  generally  not  attended    to,  we  can  hear  them  ;  and 
can  fee  the  fpeftra  of  objects,    which  remain  in  the  eye,  when- 
ever we  pleafe  to  exert  our  voluntary  power  in  aid  of  thofe  weak 
adtionsof  the  retina,  or  of  the  auditory  nerve. 

7.  The  temporary   catenations  of  ideas,  which  are  caufed  by 
the  fenfations  of  pleafure   or  pain,  are  eafily  diflevered  either  by 
irritations,  as  when  a  fudden  noife  difturbs  a  day-dream  ;  or  by 
the  power  of  volition,  as  when  we  awake  from  ileep.     Hence  in 
our  waking  hours,  whenever  an  idea  occurs,  which  is  incongru- 
ous to  our  former  experience,  we  inftantly  cliiTever  the  train  of 
imagination  by  the  power  of  volition,  and  compare  the  incon- 
gruous idea  with  our  previous   knowledge  of  nature,  and  rejeft 
it.     This  operation  of  the  mind  has  not  yet  acquired  a  fpecific 
name,  though  it  is  exerted  every  minute  of  our  waking  hours  ; 
unlefs,  it  may  be  termed  INTUITIVE  ANALOGY.     It  is  an  aft  of 
reafoning  of  which  we    are   unconfcious  except  from  its  effefts 
in  preferving  the  congruity  of  our  ideas,  and  bears  the  fame  re- 
lation to  the  fenforial  power  of  volition,  that  irritative  ideas,  of 
which  we  are  inconfcious  except  by  their  effefts,  do  to  the  fenfo- 
rial power  of  irritation  ;  as  the  former  is  produced  by  volition 
without  our  attention  to  it,  and  the  latter  by  irritation  without 
our  attention  to  them. 

If  on  the  other  hand  a  train  of  imagination  or  of  voluntary 
ideas  are  excited  with  great  energy,  and  paffing  on  with  great 
vivacity,  and  become  difTevered  by  fome  violent  itimulus,  as  the 
difcharge  of  a  piftol  near  one's  ear,  another  circumftance  takes 
place,  which  is  termed  SURPRISE  ;  which  by  exciting  violent 
irritation,  and  violent  ienfation,  employs  for  a  time  the  whole 
fenforial  energy,  and  thus  diffevers  the  pafling  trains  of  ideas, 
before  the  power  of  volition  has  time  to  compare  them  with  the 
ufual  phenomena  of  nature.  In  this  cafe  fear  is  generally  the 
companion  of  furprife,  and  adds  to  our  embarraffment,  as  every 

one 


CATENATION,  &c.          SECT.  XVII. "3. 7, 

one  experiences  in  fome  degree  when  he  hears  a  noife  in  the 
dark,  which  he  cannot  inftantly  account  for.  This  catenation 
of  ,fear  with  ;urprife  is  owing  to  our  perpetual  experience  of  in- 
juries from  external  bodies  in  motion,  unlefs  we  are  upon  our 
guard  againft  them.  See  Seel:.  XVIII.  17.  XIX.  2. 

Many  other  examples   of  the  catenations  of  animal  motions 
are  explained  in  Seel.  XXXVI.  on  the  Periods  of  Difeafes* 


SECT 


SECT.  XVIII.  i .  OF  SLEEP.  153 


SECT.      XVIII. 

OF    SLEEP. 

I.  Volition  is  Ju/pend*d  in  fleep.      2-   Sen/at  ion  continues.     Dreams 
prevent  delirium  and  inflammation.      3.   Nightmare.      4.   Ceafe- 

.  lefs  flow  of  ideas  in  dreams.  5  We  fee m  to  receive  them  by  the 
fenfes.  Optic  nerve  perfectly  fenfible  in  fleep.  Eye*  lefs  dazzled 
after  dreaming  of  vifible  objects.  6  Reverie,  belief.  7.  How 
we  diftinguifh  ideas  from  perceptions.  8  Variety  of  fcenery  in 
dreams,  excellence  of  the  fen fe  of  vijiin.  9  Novelty  of  combina- 
tion in  dreams.  \  o  Diftinclne/s  of  imagery  in  dreams.  1 1 .  Ra- 
pidity of  tranfaclion  in  dreams.  1 2.  Of  meafuring  time.  Of 
dramatic  time  and  place.  Why  a  dull  play  induces  Jleep  ^  and  an 
inter  efting  one  reverie.  13.  Confcioufnefs  of  our  exigence  and 
identity  in  dreams.  14.  How  we  awake  fometimes  fuddenly9 
fometimes  frequently.  15.  Irritative  motions  continue  in  Jleep9 
internal  irritations  are fucceeded  by  fenfition.  Senftbility  increafes 
during  Jleep  t  and  irritability.  Morning  dreams.  Why  epilepfies 
occur  injleep.  Ecjlacy  of  children.  Cafe  of  convulfions  in  Jleep. 
Cramp)  why  painful.  Aftkma.  Morning  fiveats.  Increafe  of 
heat.  Increafe  of  urine  injleep.  Why  more  liable  to  take  cold  in 
fleep.  Catarrh  from  thin  night -caps.  Why  <we  feel  chilly  at  the  • 
approach  of  Jleep>  and  at  waking  in  the  often  air.  1 6.  Why  the 
gout  commences  in  fleep.  Secretions  are  more  copious  injleep)  young 
animals  and  plants  grow  more  in  fleep.  17.  Inconjtftency  of 
dreams.  Abfence  of furprife  in  dreams.  18.  Why  we  forget 
fome  dreams  and  not  others.  19.  Sleep  talkers  awake  with  fur- 
prife. 2o.'  Remote  caufes  of  Jleep.  Atmofphere  with  lefs  oxygene. 
CompreJ/ion  of  the  brain  in  the  fpina  bifda.  By  whirling  on  a 
horizontal  wheel.  By  cold.  21.  Definition  of  Jleep. 

i.  THERE  are  four  fituations  of  our  fyftem,  which  in  their 
moderate  degrees  are  not  ufually  termed  difeafes,  and  yet 
abound  with  many  very  curious  and  inftrudlive  phenomena  ; 
thefe  are  fleep,  reverie,  vertigo,  drunkenneis.  Thefe  we  fhall 
previoufly  confider,  before  we  ftep  forwards  to  develop  the  caufes 
and  cures  of  difeafes  with  the  modes  of  the  operation  of  medi- 
cines. 

As  all  thofe  trains  and  tribes  of  animal  motion,  which  are 
fubjecl:  to  volition,  were  the  laft  that  were  caufed,  their  con- 
nexion is  weaker  than  that  of  the  other  claffes  ;  and  there  is 
a  peculiar  circumftance  attending  this  caufation,  which  is,  that 
:t  is  entirely  fufpended  during  fleep  ;  whilft  the  other  clafles  of 

VOL,  I.  W  motion, 


2  5  4  OF  SLEEP.  SECT.  XVIII.  2  > 

motion,  which  are  more  immediately  neceflary  to  life,  as  thofe 
caufed  by  internal  ftimuli,  for  inftance  the  pulfations  of  the 
heart  and  arteries,  or  thole  catenated  with  pleafurable  fenfa- 
tion,  as  the  powers  of  digeftion,  continue  to  ftrengthen  their 
habits  without  interruption.  Thus  though  man  in  his  fleeping 
ftate  is  a  much  lefs  perfect  animal,  than  in  his  waking  hours  ; 
and  though  he  confumes  more  than  one  third  of  his  life  in  this 
his  irrational  fituation  ;  yet  is  the  wifdom  of  the  Author  of  na- 
ture manifeft  even  in  this  feeming  imperfection  of  his  work. 

The  truth  of  this  aflertion  with  refpect  to  the  large  mufcles 
of  the  body,  which  are  concerned  in  locomotion,  is  evident  ; 
as  no  one  in  perfecl:  fanity  walks  about  in  his  fleep,  or  performs 
any  domeftic  offices  ;  and  in  refpect  to  the  mind,  we  never  ex- 
ercife  our  reafon  or  recollection  in  dreams;  we  may  fometimes 
feem  diffracted  between  contending  paflions,  but  we  never 
compare  their  objects,  or  deliberate  about  the  acquifition  of  thofe 
objects,  if  our  fleep  is  perfect.  And  though  many  fynchronous 
tribes  or  fucceflive  trains  of  ideas  may  reprefent  the  houfes  or 
walks,  which  have  real  exiftence,  yet  are  they  here  introduced 
by  their  connexion  with  our  fenfations,  and  are  in  truth,  ideas 
of  imagination,  not  of  recollection. 

2.  For  our  fenfations  of  pleafure  and  pain  are  experienced 
with  great  vivacity  in  our  dreams  ;  and  hence  all  that  motley 
group  of  ideas,  which  are  caufed  by  them,  called  the  ideas  of 
imagination,  with  their  various  aflbciated  trains,  are  in  a  very 
vivid  manner  acted  over  in  the  fenforium  ;  and  thefe  fometimes 
call  into  action  the  larger  mufcles,  which  have  been  much  aflb- 
ciated with  them  ;  as  appears  from  the  muttering  fentences, 
which  fome  people  utter  in  their  dreams,  and  from  the  obfcure 
barking  of  fleeping  dogs,and  the  motions  of  their  feet  and  noftrils. 

This  perpetual  flow  of  the  trains  of  ideas,  which  conftitute  our 
dreams,  and  which  are  caufed  by  painful  or  pleafurable  fenfa- 
tions, might  at  firft  view,  be  conceived  to  be  an  ufelefs  expen- 
diture of  fenforial  power.  But  it  has  been  fhewn,  that  thofe 
motions,  which  are  perpetually  excited,  as  thofe  of  the  arterial 
fyftem  by  the  ftimulus  of  the  blood,  are  attended  by  a  great  ac- 
cumulation of  fenforial  power,  after  they  have  been  for  a  time- 
fufpended  •,  as  the  hot- fit  of  fever  is  the  confluence  of  the 
cold  one.  Now  as  thefe  trains  of  ideas  caufed  by  fenfation  are 
perpetually  excited  during  our  waking  hours,  if  they  were  to  be 
fufpended  in  fleep  like  the  voluntary  motions,  (which  are  exerted 
only  by  intervals  during  our  waking  hours,)  an  accumulation 
of  fenforial  power  would  follow  •,  and  on  our  waking  a  delirium 
would  fupervene,  fince  theie  ideas  caufed  by  fenfation  would 
be  produced  with  fuch  energy,  that  we  (houid  miftake  the  trains 

of 


SECT.  XVIII.  3.  OF  SLEEP.  155 

of  imagination  for  ideas  excited  by  irritation  ;  as  perpetually 
happens  to  people  debilitated  by  fevers  on  their  firft  awaking : 
for  in  thefe  fevers  with  debility  the  general  quantity  of  irrita- 
tion being  diminifhed,  that  of  fenfation  is  increafed.  In  like 
manner  if  the  aftions  of  the  flomach,  inteftines,  and  various 
glands,  which  are  perhaps  in  part  at  lead  caufed  by  or  catenated 
with  agreeable  fenfation,  and  which  perpetually  exift  during 
our  waking  hours,  were  like  the  voluntary  motions  fufpended  in 
our  fleep  ;  the  great  accumulation  of  fenforial  power,  which 
would  necefiarily  follow,  would  be  liable  to  excite  inflammation 
in  them. 

3.  When  by  our  continued  pofture  in  fleep  fome  uneafy 
fenfations  are  produced,  we  either  gradually  awake  by  the  exer- 
tion of  volition,  or  the  mufcles  connected  by  habit  with  fuch 
fenfations  alter  the  pofition  of  the  body  ;  but  where  the  fleep  is 
uncommonly  profound,  and  thofe  uneafy  fenfations  great,  the 
difeafe  called  the  incubus,  or  nightmare,  is  produced.  Here  the 
defire  of  moving  the  body  is  painfully  exerted,  but  the  power  cf 
moving  it,  or  volition,  is  incapable  of  a&ion,  till  we  awake. 
Many  Tefs  difagreeable  druggies  in  our  dreams,  as  when  we  wifh 
in  vain  to  fly  from  terrifying  objecls,  conftitttte  a  flighter  degree 
of  this  difeafe.  In  awaking  from  the  nightmare  I  have  more 
than  once  oblerved,  that  there  was  no  diforder  in  my  pulfe ; 
nor  do  I  believe  the  refpiration  is  laborious,  as  fome  have  affirm- 
ed. It  occurs  to  people  whofe  fleep  is  too  profound,  and  fome 
difagreeable  fenfation  exifts,  which  at  other  times  would  have 
Awakened  them,  and  have  thence  prevented  the  difeafe  of  night- 
mare ;  as  after  great  fatigue  or  hunger  with  too  large  a  fupper  and 
wine,  which  occafion  our  fleep  to  be  uncommonly  profoun^i. 
See  No.  14,  of  this  Section. 

4.  As  the  larger  mufcles  of  the  body  are  much  more  fre- 
quently excited  by  volition  than  by  fenfation,  they  are  but  fel- 
dom  brought  into  a£Hon  in  our  fleep  :  but  the  ideas  of  the  mind 
are  by  habit  much  more  frequently  connected  with  fenfation 
than  with  volition  ;  and  hence  the  ceafelefs  flow  of  our  ideas  in 
dreams.     Every  one's  experience  will  teach  him  this  truth,  for 
we  all  daily  exert  much  voluntary  mufcular  motion  :  but  few 
of  mankind  can  bear  the  fatigue  of  much  voluntary  thinking. 

5.  A  very  curious  circumftance  attending  thefe  our  fleeping 
imaginations  is,   that  we  feem  to  receive  them  by  the   fenfes. 
The  mufcles,  which  are  fubfervient  to  the  external  organs  of 
fenfe,  are  connecled  with  volition,  and  ceafe  to  a£l  in  fleep  ; 
hence  the  eyelids  are  clofed,and  the  tympanum  of  the  ear  relaxed  ; 
and  it  is  probable  a  fimiiarity  of  voluntary  exertion  may  be  necef- 
fary  for  the  perceptions  of  the  other  nerves  of  fenfe  ;  for  it  it 

obferved 


OF  SLEEP.  SECT.  XVIII.  5, 

obferved  that  the  papillae  of  the  tongue  can  be  feen  to  become 
erecled,  when  we  attempt  to  tafte  any  thing  extremely  grattful. 
Hewfon  Exper.  knquir.  V.  ii.  186.  Albini  Annot.  Acad  L  i. 
c.  15.  Add  to  this,  that  the  irr  mediate  organs  of  fenfe  have  no 
objects  to  excite  them  in  the  darknefs  and  filence  of  the  night  ; 
but  their  nerves  of  fenfe  nevertheleis  continue  to  poflefs  their 
perfect  activity  fubfervient  to  all  their  numerous  fenfitive  con- 
nexions. This  vivacity  of  our  nerves  of  fenfe  during  the  time 
of  fleep  is  evinced  by  a  circumftance,  which  almoft  every  one 
muft  at  fome  time  or  other  have  experienced  ;  that  is,  if  we 
fleep  in  the  daylight,  and  endeavour  to  fee  fome  object  in  our 
dream,  the  light  is  exceedingly  painful  to  our  eyes  ;  and  after 
repeated  flruggles  we  lament  in  our  fleep,  that  we  cannot  fee  it, 
In  this  cafe  I  apprehend  the  eyelid  is  in  fome  degree  opened  by 
the  vehemence  of  our  fenfations  ;  and,  the  iris  being  dilated, 
the  optic  nerve  (hews  as  great  or  greater  fenfibiiity  than  in  our 
waking  hours.  See  No.  1 5.  of  this  Seclion. 

When  we  are  forcibly  waked  at  midnight  from  profound 
fleep,  our  eyes  are  much  dazzled  with  the  light  of  the  candle  for 
a  minute  or  two,  after  there  has  been  fufficient  time  allowed  for 
the  contraction  of  the  iris  ;  which  is  owing  to  the  accumulation 
of  fenforial  power  in  the  organ  of  vifion  during  its  flate  of  lefs 
activity.  But  v/hen  we  have  dreamt  much  of  vifible  objects, 
this  accumulation  of  fenforial  power  in  the  organ  of  vifion  is 
leflened  or  prevented,  and  we  awake  in  the  morning  without  be- 
ing dazzled  with  the  light,  after  the  iris  has  had  time  to  con- 
tract itfelf.  This  is  a  matter  of  great  curiofity,  and  may  be  thus 
tried  by  any  one  in  the  day-light.  Clofe  your  eyes,  and  cover 
them  with  your  hat  ;  think  for  a  minute  on  a  tune,  which  you 
are  accuflomed  to,  and  endeavour  to  fing  it  with  as  little  activity 
of  mind  as  pofTible.  Suddenly  uncover  and  open  your  eyes, 
and  in  one  fecond  of  time  the  iris  will  contract  itfelf,  but  you 
will  perceive  the  day  more  luminous  for  feveral  feconds,  owing 
to  the  accumulation  of  fenforial  power  in  the  optic  nerve. 

Then  again  clofe  and  cover  your  eyes,  and  think  intenfely  on 
a  cube  of  ivory  two  inches  diameter,  attending  firft  to  the  north 
and  fouth  fides  of  it,  and  then  to  the  other  four  fides  of  it  ;  then 
get  a  clear  image  in  your  mind's  eye  of  all  the  fides  of  the  fame 
cube  coloured  red ;  and  then  of  it  coloured  green  ;  and  then  of 
it  coloured  blue  ;  laftly,  open  your  eyes  as  in  the  iormer  exper- 
iment, and  after  the  firft  fecond  of  time  allowed  for  the  con- 
tra&ion  of  the  iris,  you  will  not  perceive  any  increafe  of  the 
light  of  the  day,  or  dazzling  •,  becaufe  now  there  is  no  accumu- 
lation of  fenforial  power  in  the  optic  nerve  ;  that  having  been 
expended  by  its  a£tion  in  thinking  over  vifible  objects. 

This 


SECT.  XVIII.  6.  OF  SLEEP.  153, 

This  experiment  is  not  eafy  to  be  made  at  firft,  but  by  a  few 
patient  trials  the  fact  appears  very  certain  •,  and  (hews  clearly, 
that  our  ideas  of  imagination  are  repetitions  of  the  motions  of 
the  nerve,  which  were  originally  occafioned  by  the  ftimulus  of 
external  bodies  ;  becaufe  they  equally  expend  the  fenforial  power 
in  the  organ  of  fenfe.  See  Sect.  III.  4  which  is  analogous  to 
our  being  as  much  fatigued  by  thinking  as  by  labour. 

6.  Nor  is  it  in  our  dreams  alone,  but  even  in  our  waking  rev- 
eries, and  in;reateffortsof  invention,  fo  great  is  the  vivacity  of  our 
ideas,  that  we  do  not  for  a  time   diftinguifh  them  from  the  real 
prefence  of  iubttantial  objects  :  though  the  external  organs  of 
fenfe  are  open,  and  furrounded    with  their  ufual  ftimuli.     Thus 
whilit  I  am  thinking   over  the  beautiful  valley,  through  which  I 
yefterday  travelled,  1  do  not  perceive  the  furniture  of  my  room  : 
an-d  there  are  fome,  whole  waking  imaginations  are  fo  apt  to  run 
into  perfect  reverie,  that  in  their  common  attention  to  a  favour- 
ite idea  they  do  not  hear  the  voice  of  the  companion,  who  ac- 
coits  them,  unlcfs  it  is  repeated  with  unufual  energy. 

This  perpetual  miitake  in  dreams  and  reveries,  where  our 
ideas  of  imagination  are  attended  with  a  belief  of  the  prefence 
of  external  objects,  evinces  beyond  a  doubt,  that  all  our  ideas 
are  repetitions  of  the  motions  of  the  nerves  of  fenfe,  by  which 
they  were  acquired  ;  and  that  this  belief  is  not,  as  fome  late  phi- 
lofophers  contend,  an  inftinct  neceffarily  connected  only  with 
our  perceptions. 

7.  A  curious  queflion   demands  our  attention  in  this  place  ; 
as  we  do  not  diftinguilh  in  our  dreams  and  reveries  between  our 
perceptions  of  external  objects,,  and  our  ideas  of  them  in  their 
abtence,  how  do  we  diftinguifh  them  at  any  time  r5  In  a  dream, 
if  the  Iweetnels  of  fugar  occurs  to  my  imagination,    the  white- 
nefs  and  hardnefs  of  it,  which  were  ideas  ufually  connected  with 
the  fweetnefs,  immediately  follow  in  the  train  ;  and  I  believe  a 
material  lump  of    fugar    prefent  before  my  fenfes  :  but  in  my 
waking  hours,  if  the  fweetnefs   occurs  to  my  imagination,  the 
ftimulus  of  the  table  to  my  hand,  or  of  the  window  to  my  eye, 
prevents  the  other  ideas  of  the  hardnefs  and  whitenefs  of  the  fu- 
gar from  fucceeding  ;  and  hence  I  perceive  the  fallacy,  and  dif- 
beheve  the    exiftence  of  objects  correfpondent  to  thofe  ideas, 
whofe  tribes  or   trains    are  broken  by  the  ftimulus  of  other  ob- 
jects.    And  further  in  our  waking    hours,  we  frequently  exert 
our  volition  in  comparing  prefent  appearances  with  fuch,  as  we 
have  ufually  obferved  ;  and  thus  correct  the  errors  of  one  fenfe 
by  our  general  knowledge  of  nature  by  intuitive  analogy.      See 
Sect.  XVII.  3.  7.     Whereas  in  dreams  the  power  of  volition  is 
f  ufpended,  we  can  recollect  and  compare  our  prefent  ideas  with 

none 


iS8  -OF  SLEEP.  SECT.  XVIII.  g 

none  of  our  acquired  knowledge,  and  are  hence  incapable  of  ob~ 
ferving  any  abfurdities  in  them. 

By  this  criterion  we  diftinguifh  our  waking  from  our  fleeping 
hours,  we  can  voluntarily  recoiled  our  fleeping  ideas,  when  we 
are  awake,  and  compare  them  with  our  waking  ones  ;  but  we 
cannot  in  our  fleep  voluntarily  recoiled:  our  waking  ideas  at  all. 

8.  The  vaft  variety  of  fcenery,  novelty  of  combination,  and 
diftindnefs  of  imagery,  are    other  curious  circumftances  of  our 
fleeping  imaginations.     The  variety   of  fcenery  feems  to  arife 
from  the  fuperior  activity  and  excellence  of  our  fenfe  of  vifion  ; 
which  in  an  inftant  unfolds  to  the  mind  extenfive  fields  of  pleaf- 
urable  ideas  ;  while  the  other  fenfes  colled:  their  objeds  flowly, 
and  with  little  combination  ;  add  to  this,  that  the  ideas,  which 
this  organ  prefents  us  with,  are  more  frequently  conneded  with 
our  fen  fat  Jon  than  thofe  of  anyotfaer, 

9.  The  great  novelty  of  combination  is  owing  to  another  cir- 
cumftance  $  the  trains  of  ideas,    which  are  carried  on  in  our 
waking  thoughts,   are    in  our  dreams  difievered  in  a  thoufand 
places  by  the  iufpenflon  of  volition,  and  the  abfence  of  irritative 
ideas,  and  are  hence  perpetually  falling  into  new  catenations, 
As  explained  in  Sed.  XVI.  i.  p.     For  the  power  of  volition  is 
perpetually  exerted  during  our   waking  hours  in  comparing  our 
parting  trains  of  ideas   with  our  acquired  knowledge  of  nature, 
and  thus   forms  many    intermediate   links,  in  their  catenation. 
And  the    irritative   ideas  excited  by  the  ftimulus  of  the  objeds, 
with  which  we  are  furrounded,  are  every  moment  intruded  up- 
on us,  and  form  other  links  of  our  unceafmg  catenations  of  ideas. 

10  The  abfence  of  the  flimuli  of  external  bodies,  and  of  vo- 
lition, in  our  dreams  renders  the  organ  of  fenfe  liable  to  be 
more  flrongly  affeded  by  the  powers  of  fenfation,  and  of  aflb- 
ciation.  For  our  defires  or  averfions,  or  the  obtrufions  of  fur- 
rounding  bodies,  diflever  the  fenfitive  and  aflbciate  tribes  of 
ideas  in  our  waking  hours  by  introducing  thofe  of  irritation  and 
volition  amongft  them.  Hence  proceeds  the  fuperior  diftind- 
nefs  of  pleafurable  or  painful  imagery  in  our  fleep ;  for  we  recal 
the  figure  and  the  features  of  a  long  loft  friend,  whom  we  loved, 
in  our  dreams  with  much  more  accuracy  and  vivacity  than  in 
our  waking  thoughts.  This  circumftance  contributes  to  prove, 
that  our  ideas  of  imagination  are  reiterations  of  thofe  motions 
of  our  organs  of  fenfe,  which  were  excited  by  external  objeds  ; 
becaufe  while  we  are  expofed  to  the  ftimuli  of  prefent  objeds, 
our  ideas  of  abfent  objeds  cannot  be  fo  diftindly  formed. 

ii.  The  rapidity  of  the  fucceflion  of  tranfadions  in  our 
dreams  is  almoft  inconceivable  ;  infomuch  that,  when  we  are 
accidentally  awakened  by  the  jarring  of  a  door,  which  is  opened 

into 


SECT.  XVIII.  12.  OF  SLEE?.  159 

into  our  bedchamber,  we  fometimes  dream  a  whole  hiftory  of 
thieves  or  fire  in  the  very  inftant  of  awaking. 

Daring  the  fufpenfion  of  volition  we  cannot  compare  our 
other  ideas  with  thofe  of  the  parts  of  time  in  which  they  exid  ; 
that  is,  we  cannot  compare  the  imaginary  fcene,  which  is  before 
us,  with  thofe  changes  of  it,  which  precede  or  follow  it  :  becaufe 
this  a£t  of  comparing  requires  recollection  or  voluntary  exertion. 
Whereas  in  our  waking  hours,  we  are  perpetually  making  this 
comparifon,  and  by  that  means  our  waking  ideas  are  kept  con- 
fident with  each  other  by  intuitive  analogy  ;  but  this  compari- 
fon retards  the  fucceflion  of  them,  by  occafioning  their  repeti- 
tion. Add  to  this,  that  the  tranfaclions  of  our  dreams  confid 
chiefly  of  vifible  ideas,  and  that  a  whole  hidory  of  thieves  and  fire 
may  be  beheld  in  an  indant  of  time  like  the  figures  in  a  pidture. 

1 2.  Frojn  this  incapacity  of  attending  to  the  parts  of  time  irt 
our  dreams,  arifes  our  ignorance  of  the  length  of  the  night  ; 
which,  but  from  our  condant  experience  to  the  contrary,  we 
fhould  conclude  was  but  a  few  minutes,  when  our  ileep  is  per- 
fect. The  fame  happens  in  our  reveries  :  thus  when  we  are 
poflefled  with  vehement  joy,  grief,  or  anger,  time  appears  fhort, 
for  we  exert  no  volition  to  compare  the  prefent  fcenery  with  the 
pad  or  future  ;  but  when  we  are  compelled  to  perform  thofe  ex- 
crcifes  of  mind  or  body,  which  are  unmixed  with  pailion,  as  in 
travelling  over  a  dreary  country,  time  appears  long  ;  for  our  de- 
fire  to  finifh  our  journey  occafions  us  more  frequently  to  com- 
pare our  prefent  (ituation  with  the  parts  of  time  or  place,  which 
are  before  and  behind  us. 

So  when  we  are  enveloped  in  deep  contemplation  of  any  kind, 
or  in  reverie,  as  in  reading  a  very  intereding  play  or  romance, 
we  meafure  time  very  inaccurately  ;  and  hence,  if  a  play  greatly 
affefts  our  paffions,  the  abfurdities  of  palling  over  many  days  or 
years,  and  of  perpetual  changes  of  place,  are  not  perceived  by 
the  audience  ;  as  is  experienced  by  every  one,  who  reads  or  fees 
fome  plays  of  the  immortal  Shakeipeare  :  but  it  is  neceffary  for 
inferior  authors  to  obferve  thofe  rules  of  the  irtfaw  and  TT^TTVO 
inculcated  by  Aridotle,  becaufe  their  works  do  not  intered  the 
paffions  iufficiently  to  produce  complete  reverie. 

fhofe  works,  however,  whether  a  romance  or  a  fermon,  which 
do  not  intered  us  fo  much  as  to  induce  reverie,  may  neverthe- 
lefs  incline  us  to  fleep.  For  thofe  pleafurable  ideas,  which  are 
prefented  to  us,  and  are  too  gentle  to  excite  laughter,  (which  is 
attended  with  interrupted  voluntary  exertions,  as  explained 
Sect.  XXXIV.  I.  4.)  and  which  are  not  accompained  with  any 
other  emotion,  which  ufually  excites  fome  voluntary  exertion, 
as  anger,  or  fear,  arc  liable  to  produce  ileep  j  which  confifts  in 


160  OF  SLEEP.  SECT.  XVIII.  13 

a  fufpenfion  of  all  voluntary  power.  But  if  the  ideas  thus  pre- 
fented  to  us,  iritereft  our  attention,  and  are  accompanied  with  fo 
much  pleafurable  or  painful  fenfation  as  to  excite  our  voluntary 
exertion  at  the  fame  time,  reverie  is  the  confequence.  Hence 
an  intereding  play  produces  reverie,  a  tedious  one  produces  fleep  ; 
in  the  latter  we  become  exhausted  by  attention,  and  are  not  ex- 
cited to  any  voluntary  exertion,  and  therefore  fleep  ?  in  the 
former  we  are  excited  by  fome  emotion,  which  prevents  by  its 
pain  the  fufpenfion  of  volition,  and  in  as  much  as  it  intereds  us, 
induces  reverie,  as  explained  in  the  next  Section. 

But  when  our  fleep  is  imperfect,  as  when  we  have  determin- 
ed to  rife  in  half  an  hour,  time  appears  longer  to  us  than  in 
mod  other  fituations.  Here  our  folicitude  not  to  overfleep  the 
determined  time  induces  us  in  this  imperfect  fleep  to  compare 
the  quick  changes  of  imagined  fcenery  with  the  parts  of  time  or 
place,  they  would  have  taken  up,  had  they  real  exiftence  ;  and 
that  more  frequently  than  in  our  waking  hours  ;  and  hence  the 
time  appears  longer  to  us  :  and  I  make  no  doubt,  but  the  per- 
mitted time  appears  long  to  a  man  going  to  the  gallows,  as  the 
fear  of  its  quick  lapfe  will  make  him  think  frequently  about  it. 

13.  As  we  gain  our  knowledge   of  time  by  comparing  the 
prefent  fcenery  with  the  pad   and  future,  and  of  place  by  com- 
paring the  fituations  of  objects  with  each  other  ;  fo  we  gain  our 
idea  of  confcioufnefs  by  comparing  ourfelves  with  the  fcenery 
around  us  ;  and  of  identity  by  comparing  our  prefent  confciouf- 
nefs with  our  pad  confcioufnefs  :  as  we  never  think  of  time  or 
place,  but  when  we  make  the  comparifons  above  mentioned,  fo 
we  never  think  of  confcioufnefs,  but  when  we  compare  our  own 
exiftence  with  that  of  other  objects  ;  nor  of  identity,  but  when 
we  compare  our  prefent  and  our  pad  confcioufnefs.     Hence  the 
confcioufnefs  of  our  own  exidence,  and  of  our  identity,  is  owing 
to  a  voluntary  exertion  of  our  minds  ;  and  on  that  account  in 
our  complete  dreams  we  neither  meafure  time,  are  furprifed  at 
the  fudden  changes  of  place,  nor  attend  to  our  own  exidence,  or 
identity  \  becaufe  our  power  of  volition  is  fufpended.     But  all 
theie  circumdances  are  more  or  lefs  obfervable  in  our  incom- 
plete ones  '9  for  then  we  attend  a  little  to  the  lapfe  of  time,  and 
the  changes  of  place,  and  to  our  own  exidence  ;  and  even  to 
our  identity  of  peribn  ;   for  a  lady  feldom  dreams,  that  (he  is  a 
foldier ;  nor  a  man,  that  he  is  brought  to  bed. 

14.  As  long  as  our  fenfations  only  excite  their  fenfual  mo- 
tions, or  ideas,  our  fleep  continues  found  ;  but  as  foon  as  they 
excite  defires  or  averfions,  our  fleep  becomes  imperfect ;  and 
when  that  defire  or  averfion  is  fo  drong,  as  to  produce  voluntary 
motions,  we  begin  to  awake  ;  the  larger  muicles  of  the  body  are 

brought 


SECT.  XVIIL  15.  OF  SLEEP.  161 

brought  into  aftion  to  remove  that  irritation  or  fenfation,  which 
a  continued  pofture  has  caufed  ;  we  ftretch  our  limbs,  and 
yawn,  and  our  ileep  is  thus  broken  by  the  accumulation  of  vol- 
untary power. 

Sometimes  it  happens,  that  the  aft  of  waking  is  fuddenly  pro- 
duced, and  this  foon  after  the  commencement  of  ileep  ;  which 
is  occafioned  by  fome  fenfation  fo  difagreeable,  as  inftantane- 
oufly  to  excite  the  power  of  volition  ;  and  a  temporary  action  of 
all  the  voluntary  motions  fuddenly  fucceeds,  and  we  ftart  awake. 
This  is  fometimes  accompanied  with  loud  noife  in  the  ears,  and 
with  fome  degree  of  fear  ;  and  when  it  is  in  great  excefs,  fo  as 
to  produce  continued  convulfive  motions  of  thofe  mufcles, 
which  are  generally  fubfervient  to  volition,  it  becomes  epilepfy  ; 
the  (its  of  which  in  fome  patiems  generally  commence  during 
ileep.  This  differs  from  the  nightmare  defcribed  in  No.  3.  of 
this  Section,  becaufe  in  that  the  difagreeable  fenfation  is  not  fo 
great  as  to  excite  the  power  of  volition  into  adion ;  for  as  foon 
as  that  happens,  the  difeafe  ceafes. 

Another  circumftance,  which  fometimes  awakes  people  foon 
after  the  commencement  of  their  fleep,  is  where  the  voluntary 
power  is  already  fo  great  in  quantity  as  almoft  to  prevent  them 
from  falling  afleep,  and  then  a  little  accumulation  of  it  foon 
again  awakens  them  ;  this  happens  in  cafes  of  infanity,  or 
where  the  mind  has  been  lately  much  agitated  by  fear  or  anger. 
There  is  another  circumftance  in  which  fleep  is  likewife  of 
iliort  duration,  which  arifes  from  great  debility,  as  after  great 
over- fatigue,  and  in  fome  fevers,  where  the  flrength  of  the 
patient  is  greatly  diminifhed  :  as  in  thefe  cafes  the  pulfe  inter- 
mits or  flutters,  and  the  refpiration  is  previoufly  affected,  it 
feems  to  originate  from  the  want  of  fome  voluntary  efforts  to 
facilitate  refpiration,  as  when  we  are  awake,  and  is  further 
treated  of  in  Vol.  II.  Clafs  I.  2.  i.  2,  on  the  Difeafes  of  the 
Voluntary  Power  Art.  Somnus  interruptus. 

15.  We  come  now  to  thofe  motions  which  depend  on  irrita- 
tion. The  motions  of  the  arterial  and  glandular  fyftems  con- 
tinue in  our  fleep,  proceeding  flower  indeed,  but  ftronger  and 
more  uniformly,  than  in  our  waking  hours>  when  they  are  in- 
commoded by  external  ftimuli,  or  by  the  movements  of  volition  ; 
the  motions  of  the  mufcles  fubfervient  to  refpiration  continue 
to  be  ftimulated  into  action,  and  the  other  internal  fenfes  of  hun- 
ger, thirft,  and  luft,  are  not  only  occailonally  excited  in  our  fleep, 
but  their  irritative  motions  are  face-ceded  by  their  ufual  fenfa- 
tions,  and  make  a  part  of  the  farrago  of  our  dreams.  Thefe 
fenfations  of  the  want  of  air,  of  hunger,  thirft,  and  luft,  in  our 
dreams,  contribute  to  prove,  that  the  nerves  of  the  external 
VOL.  I.  X  fenfes 


i6z  OF  SLEEP.  SECT.  XVIII.  i  j. 

fenfes  are  alfo  alive  and  excitable  In  our  fleep  •,  but  as  the  ftimuli 
of  external  objecls  are  either  excluded  from  them  by  the  dark- 
nefs  and  filence  of  the  night,  or  their  accefs  to  them  is  prevented 
by  the  fufpenfion  of  volition,  thefe  nerves  of  fenfe  fall  more 
readily  into  their  connexion  with  fenfation  and  with  aflbciation  j 
becaufe  much  fenforial  power,  which  during  the  day  was  ex- 
pended in  moving  the  external  organs  of  fenfe  in  confequence 
of  irritation  from  external  ftimuli,  or  in  confequence  of  volition, 
becomes  now  in  fome  degree  accumulated,  and  renders  the  in- 
ternal or  immediate  organs  of  fenfe  more  eafily  excitable  by  the 
other  fenforial  powers.  Thus  in  refpecT:  to  the  eye,  the  irritation 
from  external  ilimuii,  and  the  power  of  volition  during  our 
waking  hours,  elevate  the  eyelids,  adapt  the  aperture  of  the  iris 
to  the  quantity  of  light,  the  focus  of  the  cryftalline  humour,  and 
the  angle  of  the  optic  axifes  to  the  diftance  of  the  objeft,  all 
which  perpetual  activity  during  the  day  expends  much  feniorial 
power,  which  is  faved  during  our  fleep. 

Hence  it  appears,  that  not  only  thofe  parts  of  the  fyftem, 
which  are  always  excited  by  internal  ftimuli,  as  the  ftomach, 
inteftinal  canal,  bile-duels,  and  the  various  glands,  but  the  or- 
gans of  fenfe  alfo  may  be  more  violently  excited  into  aclion  by 
the  irritation  from  internal  ftimuli,  or  by  fenfation,  during  our 
fleep  than  in  our  waking  hours ;  becaufe  during  the  fufpenfion 
of  volition,  there  is  a  greater  quantity  of  the  fpirit  of  animation 
to  be  expended  by  the  other  fenforial  powers.  On  this  account 
our  irritability  to  internal  ftimuli,  and  our  fenfibility  to  pain  or 
pleafure,  is  not  only  greater  in  fleep,  but  increafes  as  our  fleep 
is  prolonged.  Whence  digeftion  and  fecretion  are  performed 
better  in  fleep,  than  in  our  waking  hours,  and  our  dreams  in  the 
morning  have  greater  variety  and  vivacity,  as  our  fenfibility  in- 
creafes, than  at  night  when  we  firft  lie  down.  And  hence  epi- 
leptic fits,  which  are  always  occafioned  by  fome  difagreeable  fen- 
fation, fo  frequently  attack  thofe,  who  are  fubjecl;  to  them,  in 
their  fleep  \  becaufe  at  this  time  the  fyilem  is  more  excitable  by 
painful  fenfation  in  confequence  of  internal  ftimuii  ;  and  the 
power  of  volition  is  then  fuddenly  exerted  to  relieve  this  pain, 
as  explained  Sed.  XXXIV.  i.  4. 

There  is  a  difeafe,  which  frequently  afFe6ts  children  in  the 
cradle,  which  is  termed  ecftafy,  and  feems  to  con  (i  ft  in  certain 
exertions  to  relieve  painful  fenfation,  in  which  the  voluntary 
power  is  not  fo  far  excited  as  totally  to  awaken  them,  and  yet  is 
fufficient  to  remove  the  difagreeable  fenfation,  which  excites 
it  ;  in  this  cafe  changing  the  pofture  of  the  child  frequently 
relieves  it. 

I  have  at  this  time  under  my  care  an  elegant  young  man 

about 


SECT.  XVIII.  15.  0F  SLEEP.  163 

about  twenty-two  years  of  age,  who  feldom  fleeps  more  than  an 
hour  without  experiencing  a  convulfion  fit;  which  ceafes  in 
about  half  a  minute  without  any  fubfequent  ftupor.  Large 
doles  of  opium  only  prevented  the  paroxyfm,  fo  long  as  they 
prevented  him  from  fleeping  by  the  intoxication,  which  they  in- 
duced. Other  medicines  had  no  effect  on  him,  He  was  gently 
awakened  every  half  hour  for  one  night,  but  without  good  ef- 
fect, as  he  foon  flept  again,  and  the  fit  returned  at  about  the 
fame  periods  of  time,  for  the  accumulated  fenforial  power,  which 
occasioned  the  increafed  fenfibility  to  pain,  was  not  thus  exhauft- 
ed.  This  cafe  evinces  that  the  fenfibility  of  the  fyftem  to  in- 
ternal excitation  increafes,  as  our  ileep  is  prolonged  ;  till  the 
pain  thus  occafioned  produces  voluntary  exertion  ;  which,  when 
it  is  in  its  ufual  degree,  only  awakens  us  j  but  when  it  is  more 
violent,  it  occafions  convulfions. 

The  cramp  in  the  calf  of  the  leg  is  another  kind  of  convul- 
fion, which  generally  commences  in  fleep,  occafioned  by  the 
continual  increafe  of  irritability  from  internal  ftirnuli,  or  of  fen- 
fibility, during  that  ftate  of  our  exigence.  The  cramp  is  a  vi- 
olent exertion  to  relieve  pain,  generally  either  of  the  Ik  in  from 
cold,  or  of  the  bowels,  as  in  fome  diarrhoeas,  or  from  the  muf- 
cles  having  been  previoufly  overflretched,  as  in  walking  up  or 
down  fteep  hills.  But  in  thefe  convulfions  of  the  mufcles,  which 
form  the  calf  of  the  leg,  the  contraction  is  fo  violent,  as  to  occa- 
fion  another  pain  in  confequence  of  their  own  too  violent  con- 
traction, as  foon  as  the  original  pain,  which  caufed  the  contrac- 
tion, is  removed.  And  hence  the  cramp,  or  fpafm,  of  thefe 
mufcles  is  continued  without  mtermiflion  by  this  new  pain,  un- 
like the  alternate  convulfions  and  remiflions  in  epileptic  fits. 
The  reafon,  that  the  contraction  of  thefe  mufcles  of  the  calf  of 
the  leg  is  more  violent  during  their  convulfion  than  that  of  oth- 
ers, depends  on  the  weaknefs  of  their  antagonift  mufcles ;  for 
after  thefe  have  been  contracted  in  their  ufual  ad  ion-,  as  at  every 
ftep  in  walking,  they  are  again  extended,  not,  as  moft  other 
mufcles  are,  by  their  antagonifts,  but  by  the  weight  of  the  whole 
body  on  the  balls  of  the  toes  ;  and  that  weight  applied  ro  great 
mechanical  advantage  on  the  heel,  that  is,  on  the  other  end  of 
the  bone  of  the  foot,  which  thus  acts  as  a  lever. 

Another  difeafe,  the  periods  of  which  generally  commence 
during  our  fleep,  is  the  afthma.  Whatever  may  be  the  remote 
caufe  of  paroxyfms  of  afthma,  the  immediate  caufe  of  the  con- 
vulfive  refpiration,  whether  in  the  common  afthma,  or  in  what 
is  termed  the  convulfive  afthma,  which  are  perhaps  only  differ- 
ent degrees  of  the  fame  difeafe,  muft  be  owing  to  violent  volun- 
tary exertions  to  relieve  pain,  as  in  other  convulfions  ;  and  the 

increafe 


i 64  OF  SLEEP.  SECT.  XVIIL  1 6. 

increafe  of  irritability  to  internal  ftimuli,  or  of  fenfibility,  during 
fleep  mud  occafion  them  to  commence  at  this  time. 

Debilitated  people,  who  have  been  unfortunately  accuftomed 
to  great  ingurgitation  of  fpirituous  potation,  frequently  part 
with  a  great  quantity  of  water  during  the  night,  but  with  not, 
more  than  ufual  in  the  day-time.  This  is  owing  to  a  beginning 
torpor  of  the  abforbent  fyftem,  and  precedes  anafarca,  which 
commences  in  the  day,  but  is  cured  in  the  night  by  the  increafe 
of  the  irritability  of  the  abforbent  fyftem  during  ileep,  which 
thus  imbibes  from  the  cellular  membrane  the  fluids,  which  had 
been  accumulated  there  during  the  day  ;  though  it  is  poffible 
the  horizontal  pofition  of  the  body  may  contribute  fomething  to 
this  purpofe,  and  alfo  the  greater  irritability  of  fome  branches 
of  the  abforbent  veflels,  which  open  their  mouths  in  the  cells  of 
the  cellular  membrane,  than  that  of  other  branches. 

As  foon  as  a  perfon  begins  to  fleep,  the  irritability  and  fenfi- 
bility of  the  fyftem  begin  to  increafe,  owing  to  the  fufpenfion  of 
volition  and  the  exclufion  of  external  (timuli.  Hence  the  ac- 
tions of  the  vefleJs  in  obedience  to  internal  ftimulation  become 
ftronger  and  more  energetic,  though  lefs  frequent  in  refpedt  to 
number.  And  as  many  of  the  fecretions  are  increafed,  fo  the 
heat  of  the  fyftem  is  gradually  increafed,  and  the  extremities  of 
feeble  people,  which  had  been  cold  during  the  day,  become 
warm.  Till  towards  morning  many  people  become  fo  warm,  as 
to  find  it  neceflary  to  throw  ofF  fome  of  their  bed-clothes,  as 
foon  as  they  awake  ;  and  in  others  fweats  are  fo  liable  to  occur 
towards  morning  during  their  fleep. 

Thus  thofe,  who  are  not  accuftomed  to  fleep  in  the  open  air, 
are  very  liable  to  take  cold,  if  they  happen  to  fall  afleep  on  a 
garden  bench,  or  in  a  carriage  with  the  window  open.  For  as 
the  fyftem  is  warmer  during  fleep,  as  above  explained,  if  a  cur- 
rent of  cold  air  afFedls  any  part  of  the  body,  a  torpor  of  that  part 
is  more  effedlually  produced,  as  when  a  could  blaft  of  air  through 
a  key- hole  or  cafement  falls  upon  a  perfon  in  a  warm  room.  In 
thofe  cafes  the  affefted  part  poflefles  lefs  irritability  in  refpeft  to 
heat,  from  its  having  previoufly  been  expofed  to  a  greater  ftim- 
ulus  of  heat,  as  in  the  warm  room,  or  during  fleep  ;  and  hence, 
when  the  ftimulus  of  heat  is  diminimed,  a  torpor  is  liable  to  en~ 
fue  5  that  is,  we  take  cold.  Hence  people  who  fleep  in  the 
open  air  generally  feel  chilly  both  at  the  approach  of  fleep,  and 
on  their  waking  ;  and  hence  many  people  are  perpetually  fub- 
je£l  to  catarrhs  if  they  fleep  in  a  lefs  warm  head-drefs,  than  that 
which  they  wear  in  the  day. 

1 6.  Not  only  the  fenforial  powers  of  irritation  and  of  fenfa- 
tion,  but  that  of  aflbciation  alfo  appear  to  a£l  with  greater  vig- 
our 


SECT.  XVIII.  1 6.  OF  SLEEP.  165 

our  during  the  fufpenfion  of  volition  in  fleep.  It  will  be  (hewn 
in  another  place,  that  the  gout  generally  firlt  attacks  the  liver, 
and  that  afterwards  an  inflammation  of  the  ball  of  the  great  toe 
commences  by  aflbciation,  and  that  of  the  liver  ceafes.  Now  as 
this  change  or  metaftafis  of  the  activity  of  the  fyflem  generally 
commences  in  fleep,  it  follows,  that  thefe  aflbciations  of  motion 
exift  with  greater  energy  at  that  time  ;  that  is,  that  the  fenforial 
faculty  of  aflbciation,  like  thofe  of  irritation  and  of  fenfation,  be- 
comes in  fome  meafure  accumulated  during  the  fufpenfion  of 
volition. 

Other  affociate  tribes  and  trains  of  motions,  as  well  as  the  ir- 
ritative and  fenfitive  ones,  appear  to  be  increafed  in  their  acliv- 
ity during  the  fufpenfion  of  volition  in  fleep.  As  thofe  which 
contribute  to  circulate  the  blood,  and  to  perform  the  various 
fecretions  as  well  as  the  aflbciate  tribes  and  trains  of  ideas, 
which  contribute  tofurnifh  the  perpetual  dreams  of  our  dream- 
ing imaginations. 

In  ileep  the  fecretions  have  generally  been  fuppofed  to  be  di- 
minifhed,  as  the  expectorated  mucus  in  coughs,  the  fluids  dif- 
charged  in  diarrhoeas,  and  in  falivation,  except  indeed  the  fecre- 
tion  of  fweat,  which  is  often  vifibly  increafed.  This  error 
feems  to  have  arifen  from  attention  to  the  exertions  rather  than 
to  the  fecretions.  For  the  fecretions,  except  that  of  fweat,  are 
generally  received  into  refervoirs,  as  the  urine  into  the  bladder, 
and  the  mucus  of  the  inteftines  and  lungs  into  their  refpective 
cavities  ;  but  thefe  refervoirs  do  not  exclude  thefe  fluids  imme- 
diately by  their  ftimulus,  but  require  at  the  fame  time  fome  vol- 
untary efforts,  and  therefore  permit  them  to  remain  during  fleep. 
And  as  they  thus  continue  longer  in  thofe  receptacles  in  our 
ileeping  hours,  a  greater  part  is  abforbed  from  them,  and  the 
remainder  becomes  thicker,  and  fometimes  in  lefs  quantity, 
though  at  the  time  it  was  fecreted  the  fluid  was  in  greater  quan- 
tity than  in  our  waking  hours.  Thus  the  urine  is  higher  col- 
oured after  long  fleep  ;  which  {hews,  that  a  greater  quantity 
has  been  fecreted,  and  that  more  of  the  aqueous  and  faline  part 
has  been  re-abforbed,  and  the  earthy  part  left  in  the  bladder  ; 
hence  thick  urine  in  fevers  fhews  only  a  greater  action  of  the 
vefiels  which  fecrete  it  in  the  kidneys,  and  of  thofe  which  abforb 
it  from  the  bladder. 

The  fame  happens  to  the  mucus  expectorated  in  coughs, 
which  is  thus  thickened  by  abforption  of  its  aqueous  and  faline 
parts  ;  and  the  fame  of  the  feces  of  the  inteftines.  From  hence 
it  appears,  and  from  what  has  been  faid  in  No.  15  of  this  Sec- 
tion concerning  the  increafe  of  irritability  and  of  fenfibility  du- 
ring iieep,  that  the  fecretions  are  in  general  rather  increafed 

than 


366  OF  SLEEP.  SECT.  XVIII.  17. 

than  diminifhed  during  thefe  hours  of  our  exidence  ;  and  it  is 
probable  that  nutrition  is  aimed  entirely  performed  in  fleep  ; 
and  that  young  animals  grow  more  at  this  time  than  in  their 
waking  hours,  as  young  plants  have  long  fince  been  obferved  to 
grow  more  in  the  night,  which  is  their  time  of  fleep. 

17.  Two  other  remarkable  circumdances  of  our  dreaming 
ideas  are  their  inconfidency,  and  the  total  abfence  of  furprife. 
Thus  we  feem  to  be  prefent  at  more  extraordinary  metamor- 
phofes  of  animals  or  trees,  than  are  to  be  met  with  in  the  fables 
of  antiquity  ;  and  appear  to  be  tranfported  from  place  to  place, 
which  leas  divide,  as  quickly  as  the  changes  of  fcenery  are  per* 
formed  in  a  play-houfe  ;  and  yet  are  not  fenfible  of  their  in- 
confi Hence,  nor  in  the  lead  degree  affe&ed  with  furprife. 

We  muft  confider  this  circumftance  more  minutely.  In  our 
waking  trains  of  ideas,  thofe  that  are  inconfiftent  with  the  ufual 
order  of  nature,  fo  rarely  have  occurred  to  us,  that  their  con- 
nexion is  the  flighted  of  all  others  :  hence,  when  a  confident 
train  of  ideas  is  exhauded,  we  attend  to  the  external  dimulir 
that  ufually  furround  us,  rather  than  to  any  inconfident  idea, 
which  might  otherwife  prefent  itfelf  :  and  if  an  inconfiftent 
idea  diould  intrude  itfelf,  we  immediately  compare  it  with  the 
preceding  one,  and  voluntarily  reject  the  train  it  would  intro- 
duce ;  this  appears  further  in  the  Section  on  Reverie,  in  which 
(late  of  the  mind  external  dimuli  are  not  attended  to,  and  yet 
the  dreams  of  ideas  are  kept  confident  by  the  efforts  of  volition. 
But  as  our  faculty  of  volition  is  fufpended,  and^all  external  dim- 
uli are  excluded  in  Jleep,,this  flighter  connexion  of  ideas  takes 
place  ;  and  the  train  is  faid  to  be  inconfident  ;  that  is,  diflimU 
lar  to  the  ufual  order  of  nature. 

But,  when  any  confident  train  of  fenfitive  or  voluntary 
ideas  is  flowing  along,  if  any  external  dimulus  afreets  us  fo  vio- 
lently, as  to  int'.uJe  irritative  ideas  forcibly  into  the  mind,  it 
difunites  the  former  train  of  ideas*  and  we  are  affected  with  fur- 
prife. Thefe  dimuli  of  unufual  energy  or  novelty  nor  only  dif- 
unite  our  common  trains  of  ideas,  but  the  trains  of  mufcular  mo- 
tions alfo,  which  have  not  been  long  edabliflied  by  habit,  ar,d 
difturb  thofe  that  have.  Some  people  become  motionlefs  by 
great  furprife,  the  fits  of  hiccup  and  of  ague  have  been  often  re- 
moved by  it,  and  it  even  affects  the  movements  of  the  heart,  and 
arteries  ;  but  in  our  fleep,  all  external  dimuli  are  excluded,  and 
in  confequnce  no  furprife  can  exid.  See  Section  XVII.  3.  7. 

1 8  We  frequently  awake  with  pleafure  from  a  dream,  which 
has  delighted  us,  without  being  able  to  recollect  the  tranfac- 
tions  of  it  ;  unlefs  perhaps  at  a  didance  of  time,  fome  analogous 
idea  may  introduce  afrefli  this  forgotten  train  :  and  in  our  wa- 

king 


.&ICT.  XVIII.  19.  OF  SLEEP.  167 

king  reveries  we  fometimes  in  a  moment  lofe  the  train  of  thought^ 
but  continue  to  feel   the  glow  of  pleafure,  or  the  deprefiion  of 
fpirits,  it  occafioned  :  whilft  at  other  times  we  can  retrace  with, 
cafe  thefe  hiftories  of  our  reveries  and  dreams. 

The  above  explanation  of  furprife  throws  light  upon  this  fub- 
jeft.  When  we  are  fuddenly  awaked  by  any  violent  flimulus, 
the  furprife  totally  difunites  the  trains  of  our  lleeping  ideas 
from  thofe  of  our  waking  ones  ;  but  if  we  gradually  awake, 
this  does  not  happen  ;  and  we  readily  unravel  the  preceding 
trains  of  imagination. 

19.  There  are  various  degrees  of  furprife  ;  the  more  intent 
we  are  upon  the    train  of  ideas,  which  we  are  employed  about, 
the  more  violent  muft  be  the  ftimulus  that  interrupts  them,  and 
the  greater  is  the  degree  of  furprife.     I  have  objferved  dogs,  who 
have  flept  by  the  fire,  and  by  their   obfcure  barking  and  ftrug- 
gling  have  appeared  very  intent  on  their  prey,  that  (hewed  great 
furprife  for  a  few  feconds  after  their  awaking  by  looking  eagerly 
around  them  ;  which  they  did  not  do  at  other  times  of  waking. 
And  an  intelligent  friend  of  mine  has  remarked,  that  his  lady, 
who  frequently  fpeaks  much  and  articulately  in  her  fleep,  could 
never  recollecl  her  dreams  in  the  morning,  when  this  happened 
to  her  :  but  that  when  (he  did  not  fpeak  in  her  fleep,  (he  could 
always  recoiled!  them. 

Hence,  when  our  fenfations  a£t  fo  (Irongly  in  fleep  as  to  in* 
fluence  the  larger  mufcles,  as  in  thofe,  who  talk  or  ftruggle  in 
their  dreams  ;  or  in  thofe,  who  are  affe&ed  with  complete  rev- 
erie (as  defcribed  in  the  next  Section),  great  furprife  is  produ- 
ced, when  they  awake  ;  and  thefe  as  well  as  thofe,  who  are 
completely  drunk  or  delirious,  totally  forget  afterwards  their 
imaginations  at  thofe  times. 

20.  As  the  immediate  caufe    of  fleep  confifts  in  the  fufpen- 
fion  of  volition,  it  follows,  that  whatever  diminifhes  the  general 
quantity  of  fenforial    power,  or  derives  it  from  the  faculty  of 
volition,  will  conftitute  a  remote  caufe  of  fleep  ;  fuch  as  fatigue 
from  mufcular  or  mental  exertion,  which  diminifhes  the  general 
quantity  of  fenforial  power;  or  an  increafe  of  the  fenfitive  mo- 
tions, as  by  attending   to  foft   mufic,  which  diverts  the  fenforial 
power  from  the  faculty  of  volition  ;  or  laftly,  by  increafe  of  the 
irritative  motions,  as  by  wine,  or  food,  or  warmth  ;  which  not 
only  by  their  expenditure  of  fenforial  power  diminim  the  quan- 
tity of  volition  ;  but  alfo   by  their  producing  pleafurable  fenfa- 
tions (which  occafions  other  mufcular  or  fenfual  motions  in  con- 
fequence),  douoiy  decieafe  the  voluntary  power,  and  thus  more 
forcibly  produce  fleep.     See  Seel:.    XXXIV.  i.  4. 

Another  method  of  inducing  fleep  is  delivered  in  a  very  inge- 
nious* 


1 68  OF  SLEEP.  SECT.  XVIH.  20 

nious  work  lately  publiflied  by  Dr.  Beddoes.  Who  after  la- 
menting that  'opium  frequently  occafions  reftleflhefs,  thinks, 
"  that  in  moft  cafes  it  would  be  better  to  induce  fleep  by  the 
abltraftion  of  ftimuli,  than  by  exhaufling  the  excitability  ;"  and 
adds,  u  upon  this  principle  we  could  not  have  a  better  foporific 
than  an  atmofphere  with  a  diminifhed  proportion  of  oxygene 
air,  and  that  common  air  might  be  admitted  after  the  patient 
was  aileep."  (Obferv.  on  Calculus,  &c.  by  Dr  Beddoes,  Mur- 
ray.) If  it  mould  be  found  to  be  true,  that  the  excitability  of 
the  fyftem  depends  on  the  quantity  of  oxygene  abforbed  by  the 
lungs  in  refpiration  according  to  the  theory  of  Dr.  Beddoes,  and 
of  M.  Girtanner,  this  idea  of  fleeping  in  an  atmofphere  with  lefs 
oxygene  in  its  competition  might  be  of  great  fervice  in  epileptic 
cafes,  and  in  cramp,  and  even  in  fits  of  the  afthma,  where  their 
periods  commence  from  the  increafe  of  irritability  during  fleep. 

Sleep  is  likewife  faid  to  be  induced  by  mechanic  preiTure  on 
the  brain  in  the  cafes  of  fpina  bifida  Where  there  has  been 
a  defect  of  one  of  the  vertebrae  of  the  back,  a  tumour  is  protru- 
ded in  confequence  ;  and,  whenever  this  tumour  has  been  com- 
prefled  by  the  hand,  fleep  is  faid  to  be  induced,  becaufe  the 
whole  of  the  brain  both  within  the  head  and  fpine  becomes  com- 
prefled  by  the  retroceffion  of  the  fluid  within  the  tumour.  But 
by  what  means  a  compreflion  of  the  brain  induces  fleep  has  not 
been  explained,  but  probably  by  diminifhing  the  fecretion  of 
fenforial  power,  and  then  the  voluntary  motions  become  fuf- 
pended  previoufly  to  the  irritative  ones,  as  occurs  in  moil  dying 
perfons. 

Another  way  of  procuring  fleep  mechanically  was  related  to 
me  by  Mr.  Brindley,  the  famous  canal  engineer,  who  was 
brought  up  to  the  bufinefs  of  a  mill-wright  j  he  told  me,  that  he 
had  more  than  once  feen  the  experiment  of  a  man  extending 
himfelf  acrofs  the  large  ftone  of  a  corn-mill;  and  that  by  gradu- 
ally letting  the  ftone  whirl,  the  man  fell  afkep,  before  the  ftone 
had  gained  its  full  velocity,  and  he  fuppofed  would  have  died 
without  pain  by  the  continuance  or  increafe  of  the  motion.  In 
this  cafe  the  centrifugal  motion  of  the  head  and  feet  muft  accu- 
mulate the  blood  in  both  thofe  extremities  of  the  body,  and  thus 
comprefs  the  brain. 

Laitly,  we  mould  mention  the  application  of  cold  ;  which, 
when  in  a  lefs  degree,  produces  watchful nefh  by  the  pain  it  oc- 
cafions, and  the  tremulous  convulfions  of  the  fubcutaneous  muf- 
cles  ;  but  when  it  is  applied  in  great  degree,  is  faid  to  produce 
fieep.  To  explain  this  efFeft  it  has  been  faid,  that  as  the  veflels 
of  the  fkin  and  extremities  become  firfl  torpid  by  the  want  of 
the  flimulus  of  heat,  and  as  thence  iefs  blood  is  circulated 

through 


SECT.  XVIII.  21.  OF  SLEEP, 

through  them,  as  appears  from  their  palenefs,  a  greater  quantity 
of  blood  poured  upon  the  brain  produces  fleep  by  its  compref- 
fion  of  that  organ.  But  I  fhould  rather  imagine,  that  the  fenfo- 
rial  power  becomes  exhaufted  by  the  convulfive  a.clions  in  con- 
fequence  of  the  pain  of  cold,  and  of  the  voluntary  exercife  pre- 
vioufly  ufed  to  prevent  it,  and  that  the  ileep  is  only  the  beginning 
to  die,  as  the  fufpenfion  of  voluntary  power  in  lingering  deaths 
precedes  for  many  hours  the  extinction  of  the  irritative  motions. 
21.  The  following  are  the  characteriftic  circumftances  at- 
tending perfect  fleep. 

1.  The  power  of  volition  is  totally  fufpended. 

2.  The  trains  of  ideas  caufed  by  fenfation  proceed  with  great- 
er facility  and  vivacity ;  but  become  inconfifterit  with  the  ufual 
order  of  nature.     The  mufcular  motions  caufed  by  fenfation 
continue  ;  as  thofe  concerned  in  our  evacuations  during  infan- 
cy, and  afterwards  in  digeftion,  and  in  priapifmus. 

3.  The  irritative   mufcular  motions  continue,   as  thofe  con- 
cerned in  the  circulation,  in  fecietion,  in  refpiration.     But  the 
irritative  fenfual  motions,  or  ideas,  are  not  excited  ;   as  the  im- 
mediate organs  of  fenfe  are  not  ftimulated  into  adion  by  exter- 
nal objects,  which  are  excluded  by  the  external  organs  of  fenfe  j 
which  are  not  in  fleep  adapted  to  their  reception  by  the  power 
of  volition,  as  in  our  waking  hours. 

4.  The  aflbciate  motions  continue  •,  but  their  firft  link  is  not 
excited  into  action  by  volition,  or  by  external  ftimuli.     In  all 
refpecls,  except  thofe  above  mentioned,  the  three  laft  fenforial 
powers  are  fomewhat  increafed  in  energy  during  the  fufpenfion 
of  volition,  owing  to  the  confequent  accumulation  of  the  fpirit 
of  animation. 


VOL,  I.  Y  ,SECI\ 


J?o  OF  REVERIE.  SECT.  XIX.  i. 

SECT.,    XIX. 

OF    REVERIE. 

i.  Various  degrees  of  reverie.  2.  Sleep-walkers.  Cafe  of  a  young 
lady.  Great  furprife  at  awaking,  dnd  total  forgetjulnejs  of 
what  paffed  in  reverie.  3.  No  Jufpenfton  of  volition  in  reverie. 
4.  Senfaive  motions  continue,  an<$kflre  conjijlent,  5.  Irritative 
motions  continue ',  but  are  not  fucceeded  b\  fen  fat  ion.  6.  Volition 
neffary  for  the  perception  of  feeble  imprejflons.  7.  Affociated  mo- 
tions continue.  8.  Nerves  of  fenfe  are  irritable  injleep>  but  not 
in  reverie.  9.  Somnambuli  are  not  ajleep.  Contagion  received 
but  once.  10.  Definition  of  reverie. 

i.  WHEN  we  are  employed  with  great  fenfation  of  pleafure, 
or  with  great  efforts  of  volition,  in  the  purfuit  of  fome  intereft- 
ing  train  of  ideas,  we  ceafe  to  be  confcious  of  our  exiftence, 
are  inattentive  to  time  and  place,  and  do  not  diftinguifti  this 
train  of  fenfitive  and  voluntary  ideas  from  the  irritative  ones  ex- 
cited by  the  prefence  of  external  objects,  though  our  organs  of 
fenfe  are  furrounded  with  their  accuilomed  ftimuli,  till  at  length 
this  interefting  train  of  ideas  becomes  exhaufted,  or  the  appulfes 
of  external  obje&s  are  applied  with  unufual  violence,  and  we  re- 
turn with  furprife,  or  with  regret,  into  the  common  track  o'f  life. 
This  is  termed  reverie  or  ftudium. 

In  fome  conilitutions  thefe  reveries  continue  a  confiderable 
time,  and  are  not  to  be  removed  without  greater  difficulty,  but 
are  experienced  in  a  lefs  degree  by  us  all ;  when  we  attend  ear- 
neilly  to  the  ideas  excited  by  volition  or  fenfation,  with  their  af- 
fociated  connexions,  but  are  at  the  fame  time  confcious  at  inter- 
vals of  the  ftimuli  of  furrounding  bodies.  Thus  in  being  pref- 
ent  at  a  play,  or  in  reading  a  romance,  fome  perfons  are  fo  totally 
abforbed  as  to  forget  their  ufual  time  of  fleep,  and  to  neglect  their 
meals ;  while  others  are  faid  to  have  been  fo  involved  in  volun- 
tary ftudy  as  not  to  have  heard  the  difcharge  of  artillery,  and 
there  is  a  ftory  of  an  Italian  politician,  who  could  think  fo  intenfe- 
ly  on  other  fubjefts,  as  to  be  infenfible  to  the  torture  of  the  rack. 

From  hence  it  appears,  that  thefe  catenations  of  ideas  and 
mufcular  motions,  which  form  the  trains  of  reverie,  are  compo- 
pofed  both  of  voluntary  and  fenfitive  afTociations  of  them  ;  and 
that  thefe  ideas  differ  from  thofe  of  delirium  or  of  fleep,  as  they 
are  kept  confident  by  the  power  of  volition  ;  and  they  differ  al- 
fo  from  the  trains  of  ideas  belonging  to  infanity,  as  they  are  as 
frequently  excited  by  fenfation  as  by  volition.  But  laftly,  that 

the 


SECT.  XIX.  2.  OF  REVERIE.  1 7 1 

the  whole  fenforial  power  is  fo  employed  on  thefe  trains  of  com- 
plete reverie,  that  like  the  violent  efforts  of  volition,  as  in  con- 
vulfions  or  infanity  ;  or  like  the  great  activity  of  the  irritative 
motions  in  drunkennefs  ;  or  of  the  fenfitive  motions  in  deliri- 
um 5  they  preclude  all  fenfation  confequent  to  external  ftimulus. 

2.  Thofe  perfons,  who  are  faid  to  walk  in  their  ileep,  are  af~ 
fefted  with  reverie  to  fo  great  a  degree,  that  it  becomes  a  for- 
midable difeafe  ;  the  effence  of  which  confifts  in  the  inaptitude 
of  the  mind  to  attend  to  external  ftimuli.  Many  hiftories  of 
this  difeafe  have  been  publilhed  by  medical  writers  ;  of  which 
there  is  a  very  curious  one  in  the  Laufanne  Tranfaftions.  I 
fhall  here  fubjoin  an  account  of  fuch  a  cafe,  with  its  cure,  for  the 
better  illuftration  of  this  fubjedl. 

A  very  ingenious  and  elegant  young  lady,  with  light  eyes  and 
hair,  about  the  age  of  feventeen,  in  other  refpefts  well,  was  fud~ 
denly  feized  foon  after  her  ufual  menftruation  with  this  very 
wonderful  malady.  The  difeafe  began  with  vehement  convul- 
fions  of  almolt  every  mufcle  of  her  body,  with  great  but  vain  ef- 
forts to  vomit,  and  the  moft  violent  hiccoughs,  that  can  be 
conceived  :  thefe  were  fucceeded  in  about  an  hour  with  a  fixed 
fpafm  ;  in  which  one  hand  was  applied  to  her  head,  and  the  other 
to  fupport  it :  in  about  half  an  hour  thefe  ceafed,  and  the  reverie 
began  fuddenly,  and  was  at  fir  ft  manifeft  by  the  look  of  her  eyes 
and  countenance,  which  feemed  to  exprefs  attention.  Then 
(he  converfed  aloud  with  imaginary  perfons  with  her  eyes  open, 
and  could  not  for  about  an  hour  be  brought  to  attend  to  the  ftim- 
ulus of  external  objefts  by  any  kind  of  violence,  which  it  was 
proper  to  ufe  :  thefe  fymptoms  returned  in  this  order  every  day 
for  five  or  fix  weeks. 

Thefe  converfations  were  quite  confident,  and  we  could  un- 
derfland,  what  fhe  fuppofed  her  imaginary  companions  to  anfwer, 
by  the  continuation  of  her  part  of  the  difcourfe.  Sometimes 
(he  was  angry,  at  other  times  (hewed  much  wit  and  vivacity,  but 
was  moft  frequently  inclined  to  melancholy.  In  thefe  reveries 
fhe  ibmetimes  fung  over  fome  rnufic  with  accuracy,  and  repeated 
whole  pages  from  the  Englifh  poets.  In  repeating  fome  lines  from 
Mr.  Pope's  works  (he  had  forgot  one  word,  and  began  again,  en- 
deavouring to  recolledl  it ;  when  fhe  came  to  the  forgotten  word 
it  was  (houted  aloud  in  her  ear,  and  this  repeatedly  to  no  pur- 
pofe  ;  but  by  many  trials  fhe  at  length  regained  it  herfelf. 

Thefe  paroxyfms  were  terminated  with  the  appearance  of  in- 
expreffible  furprife,  and  great  fear,  from  which  flie  was  fome 
minutes  in  recovering  herfelf,  called  on  her  filler  with  great  ag- 
itation, and  very  frequently  underwent  a  repetition  of  convul- 
fions,  apparently  from  the  pain  of  fear.  See  Se<ft,  XVII.  3.  7. 

After 


17*  OF  REVERIE.  SECT.  XIX.  3. 

After  having  thus  returned  for  about  an  hour  every  day  for 
two  or  three  weeks,  the  reveries  feemed  to  become  lefs  com- 
plete, and  fome  of  their  circumftances  varied  ;  fo  that  fhe  could 
walk  about  the  room  in  them  without  running  againft  any  of 
the  furniture  j  though  thefe  motions  were  at  firft  very  unfteady 
and  tottering.  And  afterwards  {he  once  drank  a  dim  of  tea,  when 
the  whole  apparatus  of  the  tea-table  was  fet  before  her  ;  and 
expreffed  fome  fufpicion,  that  a  medicine  was  put  into  it,  and 
once  feemed  to  fmell  of  a  tuberofe,  which  was  in  flower  in  her 
chamber,  and  deliberated  aloud  about  breaking  it  from  the  item, 
faying,  "  it  would  make  her  fitter  fo  charmingly  angry."  At 
another  time  in  her  melancholy  moments  fhe  heard  the  found  of 
a  pafling  bell,  u  I  \vifti  I  was  dead,"  (he  cried,  liftening  to  the 
bell,  and  then  taking  off  one  of  her  ihoes,  as  fhe  fat  upon  the 
bed,  "  I  love  the  colour  black,"  fays  (he,  "  a  little  wider,  and  a 
little  longer,  even  this  might  make  me  a  coffin  !" — Yet  it  is  evi- 
dent, (lie  was  not  fenfible  at  this  time,  any  more  than  formerly, 
of  feeing  or  hearing  any  perfon  about  her  ;  indeed  when  great 
light  was  thrown  upon  her  by  opening  the  mutters  of  the  win- 
dow, her  trains  of  ideas  feemed  lefs  melancholy  ;  and  when  I 
have  forcibly  held  her  hands,  or  covered  her  eyes,  fhe  appeared 
to  grow  impatient,  and  would  fay,  (lie  could  not  tell  what  to  do, 
for  fhe  could  neither  fee  nor  move.  In  all  thefe  circumftances 
her  pulfe  continued  unaffefted  as  in  health.  And  when  the  par- 
oxyfm  was  over,  fhe  could  never  recollect  a  fmgle  idea  of  what 
had  pafTed  in  it. 

This  aftonifhing  difeafe,  after  the  ufe  of  many  other  medi- 
cines and  applications  in  vain,  was  cured  by  very  large  dofes  of 
opium  given  about  an  hour  before  the  expected  returns  of  the 
paroxyfms  ;  and  after  a  few  relapfes,  at  the  intervals  of  three 
or  four  months,  entirely  difappeared.  But  fhe  continued  at 
times  to  have  other  fymptoms  of  epilepfy. 

3.  We  fhall  only  here  confider,   what  happened  during  the 
time  of  her  reveries,  as  that  is  our  prelent  fubjeft  •,  the  fits  of 
convulfion  belong  to  another  part  of  this  treatife.  Seft*  XXXIV. 

44- 

There  feems  to  have  been  no  fufpenfion  of  volition  during  the 

fits  of  reverie,  becaufe  fhe  endeavoured  to  regain  the  loft  idea  in 
repeating  the  lines  of  poetry,  and  deliberated  about  breaking  the 
tuberofe,  and  fuipefted  the  tea  to  have  been  medicated. 

4.  The  ideas  and  mufcular  movements  depending  on  fenfa- 
tion  were  exerted   with  their  ufual   vivacity,   and  were  kept 
from  being  inconfiftent  by  the  power  of  volition,  as  appeared 
from  her  whole  converfation,  and  was  explained  in  Seft.  XVII. 
j.  7.  and  XVIII.  16. 

;.  The 


SECT.  XIX.  5.  OF  REVERIE.  173 

5.  The  ideas  and  motions  dependent  on  irritation  during  the 
firft  weeks  of  her  difeafe,  whilft  the  reverie  was  corriplete,  were 
never  fucceeded  by  the   fenfation  of  pleafure  or  pain  j  as  (he 
neither  faw,    heard,   not   felt    any  of  the  furrounding  objects. 
Nor  was  it  certain  that  any  irritative  motions  fucceeded  the  ititn- 
ulus  of  external  objects,    till  the  reverie  became  lefs  complete, 
and  then  (he  could  walk  about  the  room  without  running  againft 
the  furniture  of  it.     Afterwards,    when  the  reverie  became  ftili 
lefs  complete  from  the  ufe  of  opium,  fome  few  irritations  were  at 
times  fucceeded  by  her  attention  to  them.      As  when  (he  fmelt 
at  a  tuberofe,  and   drank  a  diih  of  tea,  but  this  only  when  (lie 
feemed  voluntarily  to  attend  to  them. 

6.  In  common  life  when  we  liflen  to  diftant  founds,  or  wifh 
to  diftinguifh   objects   in  the  night,  we  are  obliged  (Irongly  to 
exert  our  volition  to  difpofe  the  organs  of  fenfe  to  perceive  them, 
and  to  fupprefs  the  other  trains  of  ideas,  which  might  interrupt 
thefe  feeble  fenfations.  Hence  in  the  prefent  hiftory  the  ftrong- 
eft  ftimuli  were  not  perceived,  except  when  the  faculty  of  voli- 
tion was  exerted  on    the  organ  of  ienfe  ;  and  then  even  com- 
mon ftimuli  were   fometimes  perceived  :  for  her  mind  was  fo 
ftrenuoufly  employed  in  purfuing  its  own  trains  of  voluntary  or 
fenfitive  ideas,  that  no  common  ftimuli  could  fo  far  excite  her 
attention  as  to  difunite  them  ;  that  is,  the  quanity  of  volition  or 
of  fenfation  already  exifting  was  greater  than  any,  which  could 
be  produced  in  confequence  of  common  degrees  of  ftimulation. 
But  the  few  ftimuli  of   the  tuberofe,  and  of  the  tea,  which  ihe 
did  perceive,  were  fuch,  as  accidentally  coincided  with  the  trains 
of  thought,  which  were  pairing  in  her  mind  ;  and  hence  did  not 
difunite  thofe  trains,  and  create  furprife.     And  their  being  per- 
ceived at   all  was   owing  to  the  power  of  volition  preceding  or 
coinciding  with  that  of  irritation. 

This  explication  is  countenanced  by  a  facl:  mentioned  con- 
cerning a  fomnambulift  in  the  Laufanne  Trattfeclibns,  who 
fometimes  opened  his  eyes  for  a  fliort  time  to  examine,  where 
he  was,  or  where  his  ink-pot  flood,  and  then  fhut  them  again, 
dipping  his  pen  into  the  pot  every  now  and  then*  and  writing 
on,  but  never  opening  his  eyes  Afterwards,  although  he  wrote 
on  from  line  to  line  regularly,  and  corrected  fome  errors  of  the 
pen,  or  in  fpelling  :  fo  much  eafier  was  it  to  him  to  refer  to  his 
ideas  of  the  pofitions  of  things,  than  to  his  perception?  of  them. 

7.  The  aflbciated  motions  perilled  in  their  ufual  channel,  as 
appeared  by  the   combinations  of  her  ideas,  and  the  ufe  of  her 
frmfcles,  and  the  equality  of  her  pulfe  ;  for  the  natural  motions 
of  the  arterial   fyftem,  though  originally  excited  like  other  mo- 
tions by  ftimulus,  feem   in  part  to  continue  by  their  aflbciation 

M'ith 


1 74  OF  REVERIE.  SECT.  XIX.  8, 

with  each  other.  As  the  heart  of  a  viper  pulfates  long  after  it 
is  cut  out  of  the  body,  and  removed  from  the  ftimulus  of  the 
blood. 

8-  In  the  faction  on  fleep,  it .  was  obferved  that  the  nerves  of 
fenfe  are  equally  alive  and  fufceptible  to  irritation  in  that  ftate, 
as  when  we  are  awake  ;  but  that  they  are  fecluded  from  ftimu- 
lating  objects,  or  rendered  unfit  to  receive  them  :  but  in  com- 
plete reverie  the  reverfe  happens,  the  immediate  organs  of  fenfe 
are  expofed  to  their  ufual  ftimuli ;  but  are  either  not  excited  into 
action  at  all,  or  not  into  fo  great  action,  as  to  produce  attention 
or  fenfation. 

The  total  forgetful nefs  of  what  paiTes  in  reveries  ;  and  the 
furprife  on  recovering  from  them,  are  explained  in  Section 
XVIIL  19.  and  in  Seftion  XVIL  3.  7. 

9.  It  appears  from  hence,  that  reverie  is  a  difeafe  of  the  epilep- 
tic or  cataleptic  kind,fince  theparoxyfmsof  this  young  lady  always 
began  and  frequently  terminated  with  convulfions;  and  though  in 
its  greatett  degree  it  has  been  called  fomnambulation,  or  fleep- 
walking,it  is  totally  different  from  fleep;  becaufetheeflential  char- 
acter of  fleep  confifts  in  a  total  fufpenfion  of  volition,  which  in 
reverie  is  not  affected  ;  the  eflentiai  character  of  reverie  confifts 
not  in  the  abfence  of  thofe  irritative  motions  of  our   fenfes, 
which  are  occafioned  by  the  ftimulus  of  external  objects,  but  in 
their  never  being  productive  of  fenfation.     So  that  during  a  fit 
of  reverie  that  flrange    event  happens   to  the  whole  fyftern   of 
nerves,  which  occurs  only  to  fome  particular  branches  of  them 
in  thofe,  who  are  a  fecond  time  expofed  to  the  action  of  conta- 
gious matter.     If  the   matter  of  the  fmall-pox  be  inferted  into 
the  arm  of  one,  who  has  previouily   had  that  difeafe,  it  will 
ftimulate  the  wound,  but  the  general  fenfation  or  inflammation 
of  the  fyftem  does   not  follow,    which  conflitutes  the  difeafe. 
See  Sect.  XII.  7.  6.  XXXIII.  2.  8. 

10.  The  following  is  the  definition  or  character  of  complete 
reverie,      i.  The    irritative    motions  occafioned  by  internal  fti- 
muli continue,  thofe  from  the  ftimuli  of  external  objects  are  ei- 
ther not  produced  at  all,  or   are  never  fucceeded  by  fenfation  or 
attention,  unlefs  they  are  at  the  fame  time  excited  by  volition. 
2.  The  fenfitive  motions  continue,  and  are  kept  confiftent  by  the 
power  of  volition.     3.  The  voluntary    motions  continue  undif- 
turbed.     4.  The  aflbciate  motions  continue  undifturbed. 

Two  other  cafes  of  reverie  are  related  in  Section  XXXIV.  3. 
which  further  evince,  that  reverie  is  an  effort  of  the  mind  to  re- 
lieve fome  painful  fenfation,  and  is  hence  allied  to  convulfion, 
and  to  infanity.  Another  cafe  is  related  in  Clafs  III.  i.  2.2, 

SECT. 


SECT.  XX.  i.  OF  VERTIGO.  175 

SECT.    XX. 

OF    VERTIGO. 

I .  We  determine  our  perpendicularity  by  the  apparent  motions  of  ob- 
jecls. A  perfon  hood-winked  cannot  walk  in  a  Jlraight  line. 
Dizzinefs  on  looking  from  a  tower ,  in  a  room  gained  with  uni- 
form lozenges  >  on  riding  overfnow.  2.  Dizzinefs  from  moving 
objecls.  A  whirling  wheel.  Fluctuations  of  a  river.  Experi- 
ment with  a  child.  3.  Dizzinefs  from  our  own  motions  and 
thofe  of  other  objecls.  Riding  over  a  broad  ftream.  Sea-ftcknefs. 
5  Of  turning  round  on  one  foot.  Dervifes  in  Turkey.  Atten- 
tion of  the  mind  prevents  flight  fea-Jickneft.  After  a  voyage  ideas 
cf 'vibratory  motions  are  ftill  perceived  onfhore.  6.  Ideas  con- 
tinue feme  time  after  they  are  excited.  Gircumjiances  of  turning 
on  one  foot  iflanding  on  a  tower  ^  and  walking  in  the  dark>  explain- 
ed. 7.  Irritative  ideas  of  apparent  motions.  Irritative  ideas  of 
founds.  Battemens  of  the  found  of  bells  and  organ-pipes.  Ver- 
tiginous noife  in  the  head.  Irritative  motions  of  thejiomach,  in- 
teJiineS)  and  glands.  8  Symptoms  that  accompany  vertige.  Why 
vomiting  comes  on  in  Jirokes  of  the  palfy  By  the  motion  of  ajhip. 
By  injuries  on  the  head.  Why  motion  makes  ftck  people  vomit. 
9.  Why  drunken  people  are  vertiginous.  Why  a  Jione  in  the  ure- 
ter',  or  bile-duel^  produces  vomiting.  i  o.  Why  after  a  voyage 
ideas  of  vibratory  motions  are  perceived  on  Jhore*  II.  Kinds  of 
vertigo  and  their  cure.  12.  Definition  of  vertigo. 

i.  IN  learning  to  walk  we  judge  of  the  diftancesof  the  ob- 
jefts,  which  we  approach,  by  the  eye  ;  and  by  obferving  their 
perpendicularity  determine  our  own.  This  circumftance  not 
having  been  attended  to  by  the  writers  on  vifion,  the  difeafe 
called  vertigo  or  dizzinefs  has  been  little  underftood. 

When  any  perfon  lofes  the  power  of  mufcular  aclion,  wheth- 
er he  is  ereft  or  in  a  fitting  pofture,  he  finks  down  upon  the 
ground  ;  as  is  feen  in  fainting  fits,  and  other  inftances  of  great 
debility.  Hence  it  follows,  that  fome  exertion  of  mufcular  pow- 
er is  neceflary  to  preferve  our  perpendicular  attitude.  This  is 
performed  proportionally  exerting  the  antagonilt  mufcles  of  the 
trunk,  neck,  and  limbs  ;  and  if  at  any  time  in  our  locomotions 
we  find  ourfelves  inclining  to  one  fide,  we  either  reftore  our 
equilibrium  by  the  efforts  of  the  mufcles  on  the  other  fide,  or 
by  moving  one  of  our  feet  extend  the  bafe,  which  we  reft  upon, 
to  the  new  centre  of  gravity. 

But  the  moft  eafy  and  habitual  manner  of  determining  our 

want 


OF  VERTIGO.  SECT.  XX.  a, 

want  of  perpendicularity,  is  by  attending  to  the  apparent  mo- 
tion of  the  objects  within  the  fphere  of  diftinct  vifion  ;  for  this 
apparent  motion  of  objects,  when  we  incline  from  our  perpen- 
dicularity,  or  begin  to  fall,  is  as  much  greater  than  the  real  mo- 
tion of  the  eye,  as  the  diameter  of  the  fphere  of  diftinct  vifion  is 
to  our  perpendicular  height. 

Hence  no  one,  who  is  hood-winked,  can  walk  in  a  ftraight 
line  for  a  hundred  fteps  together  ;  for  he  inclines  fo  greatly, 
before  he  is  warned  of  his  want  of  perpendicularity  by  the  fenfc 
of  touch,  not  having  the  apparent  motions  of  ambient  objects 
to  meafure  this  inclination  by,  that  he  is  neceffitated  to  move 
one  of  his  feet  outwards,  to  the  right  or  to  the  left,  to  fupport 
the  new  centre  of  gravity,  and  thus  errs  from  the  line  he  en- 
deavours to  proceed  in. 

For  the  fame  reafon  many  people  become  dizzy,  when  they 
look  from  the  fummit  of  a  tower,  which  is  raifed  much  above 
all  other  objects,  as  thefe  objects  are  out  of  the  fphere  of  dif- 
tinct vifion,  and  they  are  obliged  to  balance  their  bodies  by  the 
lefs  accurate  feelings  of  their  mufcles. 

There  is  another  curious  phenomenon  belonging  to  this  place, 
if  the  circumjacent  vifible  objects  are  fo  fmall,  that  we  do  not 
diftinguifh  their  minute  parts  ;  or  fo  fimilar,  that  we  do  not 
know  them  from  each  other  ;  we  cannot  determine  our  perpen- 
dicularity by  them.  Thus  in  a  room  hung  with  a  paper,  which 
is  coloured  over  with  fimilar  fmall  black  lozenges  or  rhomboids, 
many  people  become  dizzy  ;  for  when  they  begin  to  fall,  the 
next  and  the  next  lozenge  fucceed  upon  the  eye*,  which  they  mif- 
take  for  the  firft,  and  are  not  aware,  that  they  have  any  apparent 
motion.  But  if  you  fix  a  iheet  of  paper,  or  draw  any  other  fig- 
ure, in  the  midft  of  thefe  lozenges,  the  charm  ceafes,  and  no 
dizzinefs  is  perceptible. — The  fame  occurs  when  we  ride  over 
a  plain  covered  with  fnow  without  trees  or  other  eminent  objects. 

2.  But  afrer  having  compared  vifible  objects  at  reft  with  the 
fenfe  of  touch,  and  learnt  to  diflinguifli  their  fhapes  and  (hades, 
and  to  meaiure  our  want  of  perpendicularity  by  their  apparent 
motions,  we  come  to  confider  them  in  real  motion.  Here  a  new 
difficulty  occurs,  and  we  require  fome  experience  to  learn  the 
peculiar  mode  of  motion  of  any  moving  objects,  before  we  can 
make  ufe  of  them  for  the  purpofes  of  determining  our  perpen- 
dicularity. Thus  fome  people  become  dizzy  at  the  fight  of  a 
whirling  wheel,  or  by  gazing  on  the  fluctuations  of  a  river,  if 
no  fteady  objects  are  at  the  fame  time  within  the  fphere  of  their 
diftinct  vifion  :  and  when  a  child  firft  can  {land  erecl  upon  his 
legs,  if  you  gain  his  attention  to  a  white  hankerchief  fteadily 
extended  like  a  fajl,  and  afterwards  make  it  undulate,  he  in- 

ftantly 


SECT.  XX.  3.  OF  VERTIGO,  t?7 

ftantly  lofes  his  perpendicularity,    and  tumbles  on  the  ground. 

3.  A  fecond  difficulty  we  have  to  encounter  is  to   diftinguifh 
our  own  real  movements  from  the  apparent  motions  of  objects. 
Our  daily  practice  of  walking  and  riding  on  horfeback  foon  in^ 
ftructs  us  with  accuracy  to  difcern  thefe  modes  of  motion,  and 
to  afcribe  the  apparent   motions  of  the  ambient  objects  to  our- 
felves  ;     but  thofe,  which  we  have  not   acquired    by   repeated 
habit,  continue  to  confound  us.     So  as  we  ride  on  horfeback  the 
trees  and  cottages,  which  occur  to  us,  appear  at   reft  ;    we  can 
meafure  their  diftances  with  our  eye,  and  regulate  our  attitude 
by  them  ;  yet   if  we   carelefsJy  attend  to  diftant  hills  or  woods 
through  a  thin  hedge,  which  is  near  us,  we  obferve  the  jumping 
and   progreffive  motions  of  them  5    as   this  is  increafed  by  the 
parallax  of  thefe  objects  ;   which  we  have  not  habituated  our- 
felves   to  attend    to.     When  firft  an  European  mounts    an  ele- 
phant  fixteen  feet  high,  and  whofe  mode  of   motion  he  is   ;ot 
accuftomed  to,  the  objects  feem  to  undulate,  a$  he   pafles,  and 
he  frequently  becomes  fick  and  vertiginous,  as  I  am  well  inform- 
ed.    Any  other  unufual  movement  of  our  bodies  has   the  fame 
effect,  as  riding  backwards  in  a  coach,  fwinging  on  a  rope,  turn- 
ing round  fwiftly  on  one  leg,  fcating  on  the  ice,  and  a  thoufand 
others.     So  after  a  patient  has  been  long   confined  to  his  bed, 
when  he  firft  attempts  to  walk,  he  finds  himfelf  vertiginous,  and 
is  obliged  by  practice  to   learn  again  the  particular  modes  of  the 
apparent  motions  of  objects,  as  he  walks  by  them. 

4.  A  third  difficulty,  which  occurs  to  us  in  learning  to  balance 
ourfelves  by  the  eye,  is,  when  both  ourfelves  and   the  circumja- 
cent objects  are  in  real  motion.     Here  it  is  neceflary,  that  we 
(hould  be  habituated  to  both  thefe  modes  of  motion  in  order  to* 
preferve  our  perpendicularity.    Thus  on  horfeback  we  accurately 
obferve   another  perfon,  whom  we   meet,   trotting  towards  us, 
without  confounding  his  jumping   and  progreffive  motion  with 
our  own,  becaufe  we  have  been  accuftomed  to  them  both  j  that 
is,  to  undergo  the  one,  and  to  fee  the  other  at  the  fame    time. 
But  in  riding  over  a  broad  and  fluctuating  ftream,  though  we; 
are  well  experienced  in  the  motions  of  our  horle,    we  are  liable 
to  become  dizzy  from  our  inexperience   in    that  of  the  water. 
And  when  firft  we  go  on  (hip-board,  where  the  movements  of 
ourfelves,  and  the  movements  of  the  large  waves  are   both  new 
to  us,  the  vertigo  is   almoft  unavoidable  with  the   terrible  fick- 
nefs,  which  attends  it.     And  this  I  have  been  aflured  has  hap- 
pened to  feveral  from  being  removed  from  a  large  ihip  into  a 
imall  one  ;  and  again  from  a  fro -ill  one  inro  a  man  of  war. 

5.  From  the  foregoing  example:*  it  is  e^ :-1e»ir,  that,  when  we 
are  furrounde,d  with  unufual  motions,  we  lofe  our  perpendicu- 

VOL.  I.  hrity 


178  OF  VERTIGO.  SECT.  XX.  5. 

larity  :  but  there  are  fome  peculiar  circumftances  attending  this 
effecl:  of  moving  objects,  which  we  come  now  to  mention,  and 
{hall  hope  from  the  recital  of  them  to  gain  fome  infight  into  the 
manner  of  their  production. 

When  a  child  moves  round  quick  upon  one  foot,  the  circum- 
jacent objeds  become  quite  indiftm6t,  as  their  diftance  increafes 
their  apparent  motions  ;  and  this  great  velocity  confounds  both 
their  forms,  and  their  colours,  as  is  feen  in  whirling  round  a 
many  coloured  wheel ;  he  then  lofes  his  ufual  method  of  bal- 
ancing himfeif  by  vifion,  and  begins  to  dagger,  and  attempts  to 
recover  himfeif  by  his  mufcular  feelings  This  daggering  adds 
to  the  inilability  of  the  vifible  objedls  by  giving  a  vibratory  mo- 
tion befides  their  rotatory  one  The  child  then  drops  upon  the 
ground,  and  the  neighbouring  objefts  feem  to  continue  for  forne 
feconds  of  time  to  circulate  around  him,  and  the  earth  under 
him  appears  to  librate  like  a  balance.  In  fome  feconds  of  time 
thefe  fenfarions  of  a  continuation  of  the  motion  of  objects  van- 
i(h  ;  but  if  he  continues  turning  round  fomewhat  longer,  before 
he  falls,  ficknefs  and  vomiting  are  very  liable  to  fucceed.  But 
none  of  thefe  circumftances  affect  thofe  who  have  habituated 
themfelves  to  this  kind  of  motion,  as  the  dervifes  in  Turkey, 
amongft  whom  thefe  fwift  gyrations  are  a  ceremony  of  religion. 

In  an  open  boat  pafling  from  Leith  to  Kinghorn  in  Scotland, 
a  fudden  change  of  the  wind  (hook  the  undiftenJed  fail,  and 
ftopt  our  boat  ;  from  this  unufual  movement  the  pafiengers  all 
vomited  except  myfelf.  I  obferved,  that  the  undulation  of  the 
fhip,  and  the  inftability  of  all  vifible  objects,  inclined  me  ftrongly 
to  be  (ick  ,  and  this  continued  or  increafed,  when  I  clofed  my 
eyes,  but  as  often  as  I  bent  my  attention  with  energy  on  the 
management  and  mechanifm  of  the  ropes  and  fails,  the  ficknefs 
ceafed  ;  and  recurred  again,  as  often  as  I  relaxed  this  attention  ; 
and  I  am  allured  by  a  gentleman  of  obfervation  and  veracity, 
that  he  has  more  than  once  obferved,  when  the  veffel  has  been  in 
immediate  danger,  that  the  fea- ficknefs  of  the  paflengers  has  in- 
ftantaneoully  ceafed,  and  recurred  again,  when  the  danger  was 
over. 

Thofe,  who  have  been  upon  the  water  in  a  boat  or  (hip  fo 
long,  that  they  have  acquired  the  neceflary  habits  of  motion  up- 
on that  unftable  element,  at  their  return  on  land  frequently 
think  in  their  reveries,  or  between  lleeping  and  waking,  that 
they  obferve  the  room,  they  (it  in,  or  fome  of  its  furniture,  to 
librate  like  the  motion  of  the  veflel.  This  1  have  experienced 
myfelf,  and  have  been  told,  that  after  long  voyages,  it  is  fome 
time  before  thefe  ideas  entirely  vanifh.  The  fame  is  obfervable 
in  a  lefs  degree  after  having  travelled  fome  days  in  a  itage  coach, 


SECT.  XX.  6.  OF  VERTIGO.  179 

and  particularly  when  we  lie  down  in  bed,  and  compofe  our- 
feives  to  fltep  ;  in  this  cafe  it  is  obfervable,  that  the  rattling  noife 
of  the  coach,  as  well  as  the  unciulatory  motion,  haunts  us.  The 
drunken  vertigo,  and  the  vulgar  cuftom  of  rocking  children,  will 
be  confidered  in  the  next  Se6Uon. 

6.  The  motions  which  are  produced  by  the  power  of  voli- 
tion, may  be  immediately  (topped  by  the  exertion  of  the  fame 
power  on  the  antagonist  mufcles  ;  otherwife  theie  with  all  the 
other  clafles  of  motion  continue  to  go  on,  fome  time  after  they 
are  excited,  as  the  palpitation  oi  the  heart  continues  after  the 
object  of  fear,  which  occasioned  it,  is  removed.  But  this  cir- 
cumflance  is  in  no  clafs  of  motions  more  remarkable  than  in 
thofe  dependent  on  irrita  ion  ;  thus  if  any  one  looks  at  the  fun 
and  then  covers  his  eyes  with  his  hand,  he  will  for  many  fecoads 
of  time  perceive  the  image  of  the  fun  marked  on  his  retina  :  a 
fimilar  image  of  all  other  vifible  objects  would  remain  lome  time 
formed  on  the  retina,  but  is  extinguilhed  by  the  perpetual  change 
of  the  motions  of  this  nerve  in  our  attention  to  other  objects.  To 
this  muft  be  added,  that  the  longer  time  any  movements  have 
continued  to  be  excited  without  fatigue  to  the  organ,  the  longer 
will  they  continue  fpontaneoufly,  after  the  excitement  is  with- 
drawn :  as  the  tafte  of  tobacco  in  the  mouth  after  a  perfon  has 
been  fmoking  it.  This  tajfle  remains  fo  ftrong,  that  if  a  perfon 
continues  to  draw  air  through  a  tobacco  pipe  in  the  dark,  after 
having  been  fmoking  fome  time,  he  cannot  dtfttngmfii  whether 
his  pipe  be  lighted  or  not. 

From  thefe  two  considerations  it  appearsi  that  the  dizzinefs 
felt  in  the  head,  after  feeing  objedts  in  unufual  motion,  is  no 
other  than  a  continuation  of  the  motions  of  the  optic  nerve  ex- 
cited by  thofe  objects,  and  which  engage  our  attention.  Thus 
on  turning  round  on  one  foot,  the  vertigo  continues  for  fome 
feconds  of  time  after  the  perfon  is  fallen  on  the  ground ;  and 
the  longer  he  has  continued  to  revolve,  the  longer  will  continue 
theie  fuccefiive  motions  of  the  parts  of  the  optic  nerve. 

After  revolving  with  your  eyes  open  till  you  become  vertig- 
inous, as  foon  as  you  ceafe  to  revolve,  not  only  the  circumambi- 
ent objects  appear  to  circulate  round  you  in  a  direction  contrary 
to  that,  in  which  you  have  been  turning,  but  you  are  liable  to 
roll  your  eyes  forwards  and  backwards;  as  is  well  obferved, 
and  ingenioufly  demonstrated  by  Dr.  Wells  in  a  late  publication 
on  vifion.  The  fame  occurs,  if  you  revolve  with  your  eyes 
doled,  and  open  them  immediately  at  the  time  of  your  ceafing 
to  turn  ;  and  even  during  the  whole  time  of  revolving,  as  may- 
be felt  by  your  hand  prefled  lightly  on  your  clofed  eyelids.  To 
thefe  movements  of  the  eyes,  of  which  he  fuppofes  the  obferver 

to 


1 80  OF  VERTIGO.  SECT.  XX.  & 

to  be  inconfciousj  Dr.  Wells  afcribes  the  apparent  circumgyra- 
tion of  objects  on  ceafing  to  revolve. 

The  caufe  of  thus  turning  our  eyes  forwards,  and  then  back 
again,  after  our  body  is  at  reft,  depends,  I  imagine,  on  the  fame 
circumftance,  which  induces  us  to  follow  the  indiltinct  fpectra, 
which  are  formed  on  one  fide  of  the  centre  of  the  retina,  when 
we  obferve  them  apparently  on  clouds,  as  defcribed  in  Seel:.  XL. 
2.  2.  ;  and  then  nor  being  able  to  gain  a  more  diftinft  vifion  of 
them,  we  turn  our  eyes  back,  and  again  and  again  purfue  the  fly- 
ing (hade. 

But  this  rolling  of  the  eyes,  after  revolving  till  we  become 
vertiginous,  cannot  caufe  the  apparent  circumgyration  of  objects, 
in  a  direction  contrary  to  that  in  which  we  have  been  revolv- 
ing, for  the  following  reafons.  i.  Becaufe  in  purfuing  «  fpec- 
trum  in  the  iky  or  on  the  ground,  as  above  mentioned,  we  per- 
ceive no  retrograde  motions  of  objects.  2.  Becaufe  the  appar- 
ent retrograde  motions  of  objects,  when  we  have  revolved  till 
we  are  vertiginous,  continues  much  longer  than  the  rolling  of 
the  eyes  above  defcribed. 

3.  When  we  have  revolved  from  right  to  left,   the  apparent 
motion  of  objects,   when   we  ftop,  is  from  left  to  right ;  and 
when  we  have  revolved  from  left  to  right,  the  apparent  circula- 
tion of  objects  is  from  right  to  left :  yet  in  both  thefe  cafes  the 
eyes  of  the  revolver  are  feen  equally  to  roll  forwards  and  back- 
wards, 

4.  Becaufe  this  rolling  of  the  eyes  backwards  and  forwards 
takes  place  during  our  revolving,  as   may  be  perceived  by  the 
hand  lightly  prefled  on  the  clofed  eyelids,  and  therefore  exifta 
before  the  effect  afcribed  to  it. 

And  fifthly,  I  now  come  to  relate  an  experiment,  in  which  the 
rolling  of  the  eyes  does  not  take  place  ar  all  after  revolving,  and 
yet  the  vertigo  is  more  diftrefling  than  in  the  fituations  above 
mentioned.  If  any  one  looks  fteadily  at  a  fpct  in  the  ceiling 
over  his  head,  or  indeed  at  his  own  f  n^er  held  up  high  over  his 
head,  and  in  that  fim^tion  turns  round  till  he  becomes  giddy  ; 
and  then  flops,  and  looks  horizontally  5  he  now  finds,  that  the 
apparent  rotation  of  objects  is  from  above  downwards,  or  from 
below  upwards  ;  that  is,  that  the  apparent  circulation  of  objects 
is  now  vertical  inftead  of  horizontal,making  part  of  a  circle  round 
the  axis  of  his  eye  :  and  this  without  any  rolling  of  his  eyeball. 
The  reafon  of  there  being  no  rolling  of  the  eyeballs  perceived 
after  this  experiment,  is,becaufe  the  images  of  objects  areform- 
ed  in  rotation  round  the  axis  of  the  eye,  and  not  from  one  fide 
to  the  other  of  the  axis  of  it ;  fo  that,  as  the  eyeball  has  not 
power  to  turn  in  its  focket  round  its  own  axis,  it  cannot  follow 

the 


SECT.  XX.  6.  OF  VERTIGO.  1 8 1 

the  apparent  motions  of  thefe  evanefcent  fpeftra,  either  before 
or  after  the  body  is  at  reft  From  all  which  arguments  it  is 
rnanifeft,  that  thefe  apparent  retrograde  gyrations  of  objects  are 
no:  caufed  by  the  rolling  of  the  eye-balls  ;  firft,  becaufe  no  ap- 
parent retrogreflion  of  objects  is  obferved  in  other  rollings  of 
the  eyes.  Secondly,  becaufe  the  apparent  retrogreflion  of  ob- 
j<-cls  continues  many  feconds  after  the  rolling  of  the  eyeballs 
ceafes.  Thirdly,  becaufe  the  apparent  retrogreilion  of  objects  is 
fometimes  one  way,  and  fometimes  another,  yet  the  rolling  of 
the  eyeballs  is  the  fame  Fourthly,  becaufe  the  rolling  of  the 
eyeballs  exifts  before  the  apparent  retrograde  motions  of  objects 
ii  obferved  ;  that  is,  before  the  revolving  perfon  (lops  And 
fifthly,  becaufe  the  apparent  retrograde  gyration  of  objects  is 
pr  duced,  when  there  is  no  rolling  of  the  eyeballs  at  all. 

Dodor  Wells  imagines,  that  no  fpeclracan  be  gained  in  the 
eye,  if  <i  perfon  revolves  with  his  eyelids  clofed,  and  thinks  this 
a  tuflicient  argument  againft  the  opinion,  that  the  apparent  pro- 
grrflion  of  the  fpedlra  of  light  or  colours  in  the  eye  can  caufe 
the  apparent  retrogreflion  of  objects  in  the  vertigo  above  defcri- 
bed  *  but  it  is  certain,  when  any  perfon  revolves  in  a  light  room 
with  his  eyes  clofed,  that  he  neverthelefs  perceives  differences  of 
light  both  in  quantity  and  colour  through  his  eyelids,  as  he  turns 
round  ;  and  readily  gains  fpedtra  of  rhofe  differences.  And  thefe 
fpectra  are  not  very  different  except  in  vivacity  from  thofe,  which 
he  acquires,  when  he  revolves  with  unclofed  eyes,  fmce  if  he 
then  revolves  very  rapidly  the  colours  and  forms  of  furrounding 
objects  are  as  it  were  mixed  together  in  his  eye  ;  as  when  the 
prifmatic  colours  are  painted  on  a  wheel,  they  appear  white  as 
they  revolve.  The  truth  of  this  is  evinced  by  the  daggering  or 
vertigo  of  men  perfectly  blind,  when  they  turn  round  ;  which 
is  not  attended  with  apparent  circulation  of  objects,  but  is  a  ver- 
tiginous diforder  of  the  fenfe  of  touch.  Blind  men  balance  them- 
felves  by  their  fenfe  of  touch  ;  which,  being  lefs  adapted  for 
perceiving  fmall  deviations  from  their  perpendicular,  occafions 
them  to  carry  themfelves  more  erect  in  walking.  This  method 
of  balancing  themfelves  by  the  direction  of  their  preflure  againft 
the  floor,  becomes  difordered  by  the  unufual  mode  of  action  in 
turning  round,  and  they  begin  to  lofe  their  perpendicularity, 
that  is,  they  become  vertiginous  ;  but  without  any  apparent  cir- 
cular motions  of  vifible  objects. 

It  will  appear  from  the  following  experiments,  that  the  appar- 
ent progreflion  of  the  ocular  fpectra  of  light  or  colours  is  the 
caufe  of  the  apparent  retrogreflion  of  objedts,  after  a  perfon  has 
revolved,  till  he  is  vertiginous. 

when  a    perfon  turns   round  in  a  light  Toom  with  his 

eyes 


182  OF  VERTIGO.  SECT.  XX.  6< 

eyes  open,  but  clofcs  them  before  he  flops,  he  will  feem  to  be 
carried  forwards  in  the  direction  he  was  turning  for  a  fhort  time 
after  he  flops  But  if  he  opens  his  eyes  again,  the  objedts  before 
him  inflantly  appear  to  move  in  a  retrograde  direction,  and  he 
lofcs  the  fenfation  of  being  carried  forwards.  The  fame  occurs 
if  a  perfon  revolves  in  a  light  room  with  his  eyes  clofed  ;  when 
he  flops,  he  feems  to  be  for  a  time  carried  forwards,  if  his  eyes 
are  flill  clofed  ;  but  the  inflant  he  opens  them,  the  furrounding 
objects  appear  to  move  in  retrograde  gyration.  From  hence  it 
may  be  concluded,  that  it  is  the  fenfation  or  imagination  of  our 
continuing  to  go  forwards  in  the  direction  in  which  we  were 
turning,  that  caufes  the  apparent  retrograde  circulation  of  ob- 
jecls. 

Secondly,  though  there  is  an  audible  vertigo,  as  is  known  by 
the  battement,  or  undulations  of  found  in  the  ears,  which  many 
vertiginous  people  experience  ;  and  though  there  is  alfo  a  tangi- 
ble vertigo,  as  when  a  blind  perfon  turns  round,  as  mentioned 
above  ;  yet  as  this  circumgyration  of  objedls  is  an  hallucination 
or  deception  of  the  fenfe  of  fight,  we  are  to  look  for  the  caufe 
of  our  appearing  to  move  forward,  when  we  flop  with  our  eyes 
clofed  after  gyration,  to  fome  affedlion  of  this  fenfe.  Now, 
thirdly,  if  the  fpeclra  formed  in  the  eye  during  our  rotation  con- 
tinue to  change,  when  we  ftand  flill,  like  the  fpeclra  defcribed 
in  Seft.  III.  3.  6.  fuch  changes  muft  fugged  to  us  the  idea  or 
fenfation  of  our  flill  continuing  to  turn  round  ;  as  is  the  cafe, 
when  we  revolve  in  a  li^ht  room,  and  clofe  our  eyes  before  we 
Hop  And  lalily,  on  opening  our  eyes  in  the  fituation  above 
defcribed,  the  objc~c~ls  we  chance  to  view  amid  thefe  changing 
fpe&ra  in  the  eye,  mufl  ietm  to  move  in  a  contrary  direction ; 
as  the  moon  fometinje^  appears  to  move  retrograde,  when  fwift- 
gliding  clouds  are  puffing  forwards  fo  much  nearer  the  eye  of 
the  beholder. 

To  make  obfervations  on  faint  occular  fpedlra  requires  fome 
degree  of  habit,and  compofureof  mind,  and  even  patience*,  fome 
of  thofe  defcribed  in  Se£l.  XL.  were  found  difficult  to  fee,  by 
many,  who  tried  them  $  now  it  happens,  that  the  mind,  during 
the  confufion  of  vertigo,  when  all  the  other  irritative  tribes  of 
motion,  as  well  as  thofe  of  vifion,  are  in  fome  degree  diflurbed, 
together  with  the  fear  of  falling,  is  in  a  very  unfit  flate  for  the 
contemplation  of  fuch  weak  fenfations,  as  are  occafioned  by  faint 
ocular  fpeclra.  Yet  after  frequently  revolving,  both  with  my 
eyes  clofed,  and  with  them  open,  and  attending  to  the  fpe£ira 
remaining  in  them,  by  fhading  the  light  from  my  eyelids  more 
or  lefs  with  my  hand,  I  at  length  ceafed  to  have  the  idea  of  going 
forward,  after  I  flopped  with  my  eyes  clofed  5  and  faw  changing 

fpecTra 


SECT.  XX.  6.  OF  VERTIGO.  183 

fpeftra  in  my  eyes,  which  feemed  to  move,  as  it  were,  over  the 
field  of  vifion  •,  till  at  length,  by  repeated  trials  on  funny  days, 
I  perfuaded  myfelf,  on  opening  my  eyes,  after  revolving  forne- 
time,  on  a  (helf  of  gilded  books  in  my  library,  that  I  could  per- 
ceive the  fpe£tra  in  my  eyes  move  forwards  over  one  or  two  of 
the  books,  like  the  vapours  in  the  air  of  a  fummer's  day ;  and 
could  fo  far  undeceive  myfelf,  as  to  perceive  the  books  to  (land 
ftill.  After  more  trials  I  fometimes  brought  myfelf  to  believe, 
that  I  faw  changing  fpectra  of  lights  and  diodes  moving  in  my 
eyes,  after  turning  round  for  fome  time,  but  did  not  imagine 
either  the  fpeclra  or  the  objects  to  be  in  a  (late  of  gyration.  I 
fpeak,  however,  with  diffidence  of  thefe  facts,  as  I  could  not  al- 
ways make  the  experiments  fucceed,  when  there  was  not  a  ftrong 
light  in  my  room,  or  when  my  eyes  were  not  in  the  moil  proper 
{late  for  fuch  obfervations. 

The  ingenious  and  learned  M.  Sauvage  has  mentioned  other 
theories  to  acccount  for  the  apparent  circumgyration  of  objects  in 
vertiginous  people.  As  the  retrograde  motions  of  the  particles 
of  blood  in  the  optic  arteries,  by  fpafm,  or  by  fear,  as  is  feen  in 
the  tails  of  tadpoles,  and  membranes  between  the  ringers  of  frogs. 
Another  caufe  he  thinks  may  be  from  the  librations  to  one  fide, 
and  to  the  other,  of  the  cryftalline  lens  in  the  eye,  by  means  of 
involuntary  actions  of  the  mufcles,  which  conftitute  the  ciliary 
procefs.  Both  thefe  theories  lie  under  the  fame  objection  as 
that  of  Dr.  Wells  before  mentioned  ;  namely,  that  the  apparent 
motions  of  objects,  after  the  obferver  has  revolved  for  fome 
time,  (hould  appear  to  vibrate  this  way  and  that ;  and  not  to  cir- 
culate uniformly  in  a  direction  contrary  to  that,  in  which  the  ob- 
ferver had  revolved. 

M.  Sauvage  has,  laftly,  mentioned  the  theory  of  colours  left  in 
the  eye,  which  he  has  termed  impreflions  on  the  retina.  He  fays, 
"  Experience  teaches  us,  that  impreflions  made  on  the  rerina  by 
a  vifible  object  remain  fome  feconds  after  the  object  is  removed  ; 
as  appears  from  the  circle  of  fire  which  we  fee,  when  a  fire-dick 
is  whirled  round  in  the  dark  ;  therefore  when  we  are  carried 
round  our  own  axis  in  a  circle,  we  undergo  a  temporary  vertigo, 
when  we  flop  ;  becaufe  the  impreflions  of  the  circumjacent  ob- 
jects remain  for  a  time  afterwards  on  the  retina."  Nofolog. 
Method.  Claf.  VIII  i.  i.  We  have  before  obferved,  that  the 
changes  of  thefe  colours  remaining  in  the  eye,  evinces  them  to 
be  motions  of  the  fine  terminations  of  the  retina,  and  not  impref- 
fions  on  it  j  as  impreflions  on  a  paflive  fubftance  muft  either  re- 
mam,  or  ceafe  inrirely. 

Having  reperufed  the  ingenious  Effay  of  Dr.  Wells  on  Single 
Vifion,  and  his  additional  obfervations  in  the  Gentleman's  Mag- 
azine 


i84  OF  VERTIGO.  SECT.  XX.  6. 

azine  on  the  apparent  retrogreffion  of  obje&s  in  vertigo,  I  am 
induced  to  believe,  that  this  apparent  retrogreffion  of  objects  is 
not  always  owing  to  the  fame  caufe. 

When  a  perfon  revolves  with  his  eyes  clofed,  till  he  becomes 
vertiginous,  and  then  (lands  (till,  without  opening  them,  he  feems 
for  a  while  to  go  forward  in  the  fame  direction.  This  halluci- 
nation of  his  ideas  cannot  be  owing  to  ocular  fpt-ftra,  bec^ufe, 
as  Dr.  Wells  obferves,  no  fuch  can  have  been  formed  ;  but  it 
muft  arife  from  a  fimilar  continuance  or  repetition  of  ideas  be- 
longing to  the  fenfe  of  touch,  initead  of  to  the  fenfe  of  vifion  j 
and  (hould  therefore  be  called  a  tangible,  not  a  vifual,  vertigo. 
In  common  language  this  belief  of  continuing  to  revolve  for 
fome  time,  after  he  (lands  ftill,  when  a  perfon  has  turned  round 
for  a  minute  in  the  dark,  would  be  called  a  deception  of  imagin- 
ation. 

Now  at  this  time  if  he  opens  his  eyes  upon  a  gilt  book,  placed 
with  other  books  on  a  (helf  about  the  height  of  his  eye,  the  gilt 
book  feems  to  recede  in  the  contrary  direction  j  though  his  eyes 
are  at  this  time  kept  quite  ftill,  as  well  as  the  gilt  book.  For 
if  his  eyes  were  not  kept  ftill,  other  books  would  fall  on  them  in 
fucceflion  •,  which  when  I  repeatedly  made  the  experiment,  did 
not  occur ;  and  which  thus  evinces,  that  no  motion  of  the  eyes 
is  the  caufe  of  the  apparent  rerroceffion  of  the  gilt  book.  Why 
then  does  it  happen  ? — Certainly  from  an  hallucination  of  ideas, 
or  in  common  language  the  deception  of  imagination. 

The  vertiginous  perfon  flill  imagines  that  he  continues  to  re- 
volve forwards,  after  he  has  opened  his  eyes  •,  and  in  confe- 
quence  that  the  objects,  which  his  eyes  happen  to  fall  upon,  are 
revolving  backward  •,  as  they  would  appear  to  do,  if  he  was  ac- 
tually turning  round  with  his  eyes  open.  For  he  has  been  ac- 
cuftomed  to  obferve  the  motions  of  bodies,  whether  apparent  or 
real,  fo  much  more  frequently  by  the  eye  than  by  the  touch  ;  that 
the  pretent  belief  of  his  gyration,  occafioned  by  the  hallucina- 
tions of  the  fenfe  of  touch,  is  attended  with  ideas  of  fuch  imag- 
ined motions  of  vifible  objefts,  as  have  always  accompanied  his 
former  gyrations,  and  have  thus  been  aflbciated  with  the  mufcu- 
lar  actions  and  perceptions  of  touch,  which  occurred  at  the 
fame  time. 

When  the  remains  of  colours  are  feen  in  the  eye,  they  are 
termed  occular  fpe6tra  ;  when  remaining  founds  are  heard  in 
the  ear,  they  may  be  called  auricular  murmurs  ;  but  when  the  re- 
maining motions,  or  ideas,  of  the  ienfe  of  touch  continue,  as  in 
this  vertigo  of  a  blind-folded  perfon,  they  have  acquired  no  name, 
but  may  be  termed  evanefcent  titillations,  or  tangible  hallucina- 
tions. 

Whence 


SECT.  XX.  6.  OF  VERTIGO.  185 

Whence  I  conclude  that  vertigo  may  have  for  its  caufe  ei- 
ther the  ocular  fpeftra  of  the  fenfe  of  vifion,  when  a  perfon 
revolves  with  his  eyes  open  ^  or  the  auricular  murmurs  of  the 
fenfe  of  hearing,  if  he  is  revolved  near  a  cafcade  ;  or  the  evanef- 
cent  titillations  of  the  fenfe  of  touch,  if  he  revolves  blindfold. 
All  thefe  I  (hould  wi(h  to  call  vanifhing  ideas,  or  fenfual  motions, 
of  thofe  organs  of  fenfe  ;  which  ideas,  or  fenfual  motions,  have 
lately  been  aflbciated  in  a  circle,  and  therefore  for  a  time  con- 
tinue to  be  excited.  And  what  are  the  ideas  of  colours,  when 
they  are  excited  by  imagination  or  memory,  but  the  repetition 
of  finer  ocular  fpe&ra  ?  What  the  idea  of  founds,  but  the  repe- 
titon  of  finer  auricular  murmurs  ?  And  what  the  ideas  of  tangi- 
ble objects,  but  the  repetition  of  finer  evanefcent  titillations  ? 

The  tangible,  and  the  auricular,  and  the  vifual  vertigo,  are  all 
perceived  by  many  people  for  a  day  or  two  after  long  travelling 
in  a  boat  or  coach  ;  the  motion  of  the  veflel,  or  vehicle,  or  of 
the  furrounding  obje&s,  and  the  noife  of  the  wheels  and  oars, 
occur  at  intervals  of  reverie,  or  at  the  commencement  of  flsep. 
See  :>e£l.  XX.  5.  Thefe  ideas,  or  fenfual  motions,  of  fight,  of 
hearing,  and  of  touch,  are  fucceeded  by  the  fame  effedls  as  the 
ocular  ipeftra,  the  auricular  murmurs,  and  the  evanefcent  titil- 
lations above  mentioned ;  that  is,  by  a  kind  of  vertigo,  and  can- 
not in  that  refpeft  be  diftinguiihed  from  them.  Which  is  a  fur- 
ther confirmation  of  the  truth  of  the  dodrine"  delivered  in  Se£K 
III.  of  this  work,  that  the  colours  remaining  in  the  eyes,  which 
are  termed  ocular  fpeftra,  are  ideas,  or  fenfual  motions,  belong- 
ing to  the  fenfe  of  vifion,  which  for  too  long  a  time  continue 
their  a£Hvity. 

Any  one,  who  ftands  alone  on  the  top  of  a  high  tower,  if  he 
has  not  been  accullomed  to  balance  himfelf  by  objefts  placed  at 
fuch  diftances  and  with  fuch  inclinations,  begins  to  dagger,  and 
endeavours  to  recover  himfelf  by  his  mufcular  feelings.  During 
this  time  the  apparent  motion  of  objects  at  a  diftance  below  him 
is  very  great,  and  the  fpectra  of  thefe  apparent  motions  continue 
a  little  time  after  he  has  experienced  them ;  and  he  is  perfuaded 
to  incline  the  contrary  way  to  counteract  their  effecfh  ;  and 
either  immediately  falls,  or  applying  his  hands  to  the  building, 
ufes  his  mufcular  feelings  to  preferve  his  perpendicular  attitude, 
contrary  to  the  erroneous  perfuafions  of  his  eyes  Whild  the 
pevfon,  who  walks  in  the  dark,  daggers,  but  without  dizzinefs; 
for  he  neither  has  the  fenfation  of  moving  objefts  to  take  off  his 
attention  from  his  mufcular  feelings,  nor  has  he  the  fpeftra  of 
thofe  motions  continued  on  his  retina  to  add  to  his  confufion. 
It  happens  indeed  fometimes  to  one  dandirig  on  a  tower,  that 
the  idea  of  his  not  having  room  to  extend  his  bafe  by  moving 
VOL.  I.  A  A  one 


1 86  OF  VERTIGO.  SECT.  XX.  7. 

one  of  his  feet  outwards,  when  he  begins  to  incline,  fuperadds 
fear  to  his  other  inconveniencies ;  which  like  furprife,  joy,  or 
any  great  degree  of  fenfation,  enervates  him  in  a  moment,  by 
employing  the  whole  fenforial  power,  and  by  thus  breaking  all 
the  affociated  trains  and  tribes  of  motion. 

7;  The  irritative  ideas  of  objects,  whilft  we  are  awake,  are 
perpetually  prefent  to  our  fenfe  of  fight ;  as  we  view  the  furni- 
ture of  our  rooms,  or  the  ground  we  tread  upon,  throughout  the 
whole  day  without  attending  to  it.  And  as  our  bodies  are  never 
at  perfect  Yeft  during  our  waking  hours,  thefe  irritative  ideas  of 
objeds  are  attended  perpetually  with  irritative  ideas  ot  their  ap- 
parent motions  The  ideas  of  apparent  motions  are  always  ir- 
ritative ideas,  becaufe  we  never  attend  to  them,  whether  we  at- 
tend to  the  objects  themfelves  or  to  their  real  motions,  or  to 
neither.  Hence  the  ideas  of  the  apparent  motions  of  objects  are 
a  complete  circle  of  irritative  ideas,  which  continue  throughout 
the  clay. 

Alfo  during  all  our  waking  hours,  there  is  a  perpetual  con- 
fufed  found  of  various  bodies,  as  of  the  wind  in  our  rooms,  the 
fire,  diilant  conversation,  mechanic  bufmefs  ;  this  continued 
buzz,  as  we  are  feldom  quite  motionlefs,  changes  its  loudnefs 
perpetually,  like  the  found  of  a  bell ;  which  rifes  and  falls  as 
long  as  it  continues,  and  feems  to  pulfate  on  the  ear.  This  any 
one  may  experience  by  turning  himfelf  round  near  a  waterfall  : 
or  by  ftriking  a  glafs  bell,  and  then  moving  the  direction  of  its. 
mouth  towards  the  ears,  or  from  them,  as  long  as  its  vibrations 
continue.  Hence  this  undulation  of  indiftincl  found  makes 
another  concomitant  circle  of  irritative  ideas,  which  continues 
throughout  the  day. 

We  hear  this  undulating  found,  when  we  are  perfectly  at  reft 
ourfelves,  from  other  fonorous  bodies  befides  bells  ;  as  from  two 
organ-pipes,  which  are  nearly  but  not  quite  in  unifon,  when  they 
are  founded  together.  When  a  bell  is  (truck,  the  circular  form 
is  changed  into  an  elliptic  one  ;  the  longeft  axis  of  which,  as  the 
vibrations  continue,  moves  round  the  periphery  of  the  bell ;  and 
when  either  axis  of  this  ellipfe  is  pointed  towards  our  ears,  the 
found  is  louder ;  and  lefs  when  the  intermediate  parts  of  the 
eliipfe  are  oppofite  to  us.  The  vibrations  of  the  two  organ- 
pipes  may  be  compared  to  Nonius's  rule  ;  the  found  is  louder, 
when  they  coincide,  and  lefs  at  the  intermediate  times.  But,  as 
the  found  of  beils  is  the  mod  familiar  of  thof  founds,  which 
have  a  confiderable  batfement,  the  vertiginous  patients,  who  at- 
tend to  the  irritative  circles  of  founds  above  defcribed,  generally 
compare  it  to  the  noife  of  bells. 

The  periftaltic  motions  of  our  ftomach  and  inteftines,  and  the 

fecretions 


SECT.  XX.  8.  OF  VERTIGO.  187 

fecretions  of  the  various  glands,  are  other  circles  of  irritative 
motions,  fome  of  them  more  or  lefs  complete,  according  to  our 
abftinence  or  fatiety. 

So  that  the  irritative  ideas  of  the  apparent  motions  of  obje 61  s, 
the  irritative  battements  of  founds,  and  the  movements  of  our 
bowels  and  glands,  compofe  a  great  circle  of  irritative  tribes  of 
motion  :  and  when  one  confiderable  part  of  this  circle  of  mo- 
tions becomes  interrupted,  the  whole  proceeds  in  confufion,  a$ 
defcribed  in  Sedlion  XVII.  i.  7.  on  Catenation  of  Motions. 

8.  Hence  a  violent  vertigo,  from  whatever  caufe  it  happens, 
is  generally  attended  with  undulating  noife  in  the  head,  perver- 
lions  of  the  motions  of  the  ftomach  and  duodenum,  unufual  ex- 
cretion  of   bile  and  gaftric  juice,  with  much  pale  urine,  fome- 
times  with  yellownefs  of  the  ildn,  and  a  difordered  fecretion  of 
almoft  every  gland  of  the  body,  till  at  length  the  arterial  fyftem 
is  affefted,  and  fever  fucceeds. 

Thus  bilious  vomitings  accompany  the  vertigo  ocafioned  by 
the  motion  of  a  (hip  ;  and  when  the  brain  is  rendered  vertigin- 
ous by  a  paralytic  affection  of  any  part  of  the  body,  a  vomiting 
generally  enfues,  and  a  great  difcharge  of  bile  :  and  hence  great 
injuries  of  the  head  from  external  violence  are  fucceeded  by  bil- 
ious vomitings,  and  fometimes  by  abfcefles  of  the  liver.  And 
hence,  when  a  patient  is  inclined  to  vomit  from  other  caufes,  as 
in  fome  fevers,  any  motions  of  the  attendants  in  his  room,  or  of 
himfelf  when  he  is  raifed  or  turned  in  his  bed,  prefently  induces 
the  vomiting  by  fuperadding  a  degree  of  vertigo. 

9.  And  converfely  it  is  very  ufual  with  thofe,  whofe  ftomachs 
are  affected   from    internal  caufes,  to  be  afflicted  with  vertigo, 
and  noife  in  the  head  ;  fuch  is  the  vertigo  of  drunken  people, 
which  continues,  when  their  eyes  are  clofed,  and  themfelves  in  a 
recumbent  pofture,  as  well  as  when  they  are  in  an  erect  pofture, 
and  have  their  eyes  open.     And  thus  the  irritation  of  a  ftone  in 
the  bile-dudl,  or  in  the  ureter,  or  an  inflammation  of  any  of  the 
inteftines,  are  accompanied  with  vomitings  and  vertigo. 

In  theie  cafes  the  irritative  motions  of  the  ftomach,  which  are 
in  general  not  attended  to,  become  fo  changed  by  fome  unnat- 
ural ftimulus,  as  to  become  uneafy,  and  excite  our  fenfation  or 
attention.  And  thus  the  other  irritative  trains  of  motions, 
which  are  affociated  with  it,  become  difordered  by  their  fympa- 
thy.  The  fame  happens,  when  a  piece  of  gravel  flicks  in  the 
ureter,  or  when  fome  part  of  the  inteftinal  canal  becomes  infla- 
med. In  thefe  cafes  the  irritative mufcular  motions  are  firft  dif- 
turbed  by  unufual  ftimulus,  and  a  difordered  action  of  the  fen- 
fual  motions,  or  dizzinefs  enfues.  While  in  fea-ficknefs  the  dif- 
turbance  of  the  irritative  fenfual  motions,  as  vertigo,  precedes  ; 


i9o  OF  VERTIGO.  SECT.  XX.  12, 

hence  it  appears,  that  the  means  of  cure  muft  be  adapted  to 
the  caufe. 

To  prevent  fea-ficknefs  it  is  probable,  that  the  habit  of  fwing- 
ing  for  a  week  or  two  before  going  on  (hip  board  might  be  of 
fervice.  For  the  vertigo  from  failure  of  fight,  fpedacles  may  be 
ufed.  For  the  auditory  vertigo,  aether  may  be  dropt  into  the  ear 
to  ftimulate  the  part,  or  to  diflblve  ear-wax,  if  fuch  be  a  part  of 
the  caufe.  For  the  vertigo  arifing  from  indigeftion,  the  peruvi- 
an  bark  and  a  blifter  are  recommended.  And  for  that  owing 
to  a  ftone  in  the  ureter,  venfe&ion,  cathartics,  opiates,  fal  foda 
aerated. 

12.  Definition  of  vertigo,  i.  Some  of  the  irritative  fenfual, 
or  mufcular  motions,  which  were  ufually  not  fucceeded  by  fen- 
fation,  are  in  this  difeafe  fucceeded  by  fenfation  ;  and  the  trains 
or  circles  of  motions,  which  were  ufually  catenated  with  them, 
are  interrupted,  or  inverted,  or  proceed  in  confufion.  2.  The 
fenfiriveand  voluntary  motions  continue  undifturbed.  3.  The 
affociate  trains  or  circles  of  motions  continue  ;  but  their  catena- 
tions with  fome  of  the  irritative  motions  are  disordered,  or  in« 
verted,  or  diflevered. 


SECT, 


SECT.  XXI.  i.        OF  DRUNKENNESS.  191 

SECT.      XX. 

OF   DRUNKENNESS. 

I.  Sleep  from  fatiety  of  hunger.  From  rocking  children.  From 
uniform  founds.  2*  Intoxication  from  common  food  after  fatigue 
and  inanition.  3.  From  •wine  or  opium.  Chilnefi  ajter  meals. 
Vertigo.  Why  pleafure  is  produced  by  intoxication,  and  byfiving- 
ing  and  rocking  children.  And 'why  pain  is  relieved  by  it.  4. 
Why  drunkards  Jl agger  andjlammer,  and  are  liable  to  weep.  5 . 
And  become  delirious  ^  Jleepy  andjlupid.  6.  Of  make  pale  urine 
and  vomit.  7.  Objecls  arefeen  double.  8  Attention  of  the  mind 
diminishes  drunkennefs.  9.  Difordered  irritative  motions  of  all 
thefenfes.  10.  Difsafes  from  drunkennefs.  II.  Definition  of 
drunkennefs. 

1.  IN  the  ftate  of  nature  when  the  fenfe  of  hunger  is  appeafed 
by  the  ftimulus  of  agreeable  food,  the   bufinefs   of  the  day  is 
over,  and  the  human  fa?age  is  at  vpeace  with  the  world,  he  then 
exerts  little  attention  to  external  objects,  pleafing  reveries  of  im- 
agination fucceed,  and  at  length  fleep  is  the  refult :  till  the  nour- 
ifhment  which  he  has  procured,  is  carried  over  every  part  of  the 
fyftem  to  repair  the  injuries  of  action,    and  he  awakens  with 
frefh  vigour,  and  feels  a  renewal  of  his  fenfe  of  hunger. 

The  juices  of  fome  bitter  vegetables,  as  of  the  poppy  and  the 
laurocerafus,  and  the  ardent  fpirit  produced  in  the  fermentation 
of  the  fugar  found  in  vegetable  juices,  are  fo  agreeable  to  the 
nerves  of  the  ftomach,  that,  taken  in  a  fmall  quantity,  they  in- 
itantly  pacify  the  fenfe  of  hunger;  and  the  inattention  to  external 
ftimuli  with  the  reveries  of  imagination,  and  fleep,  fucceeds,  in 
the  fame  manner  as  when  the  ftomach  is  filled  with  other  lefs 
intoxicating  food. 

This  inattention  to  the  irritative  motions  occafioned  by  ex- 
ternal ftimuli  is  a  very  important  circumftance  in  the  approach 
of  fleep,  and  is  produced  in  young  children  by  rocking  their  cra- 
dles: during  which  all  vifible  objects  become  indiltinct  to  them. 
An  uniform  foft  repeated  found,  as  the  murmurs  of  a  gentle  cur- 
rent, or  of  bees,  are  faid  to  produce  the  fame  effect,  by  prefent- 
ing  indiftinct  ideas  of  inconfequential  founds,  and  by  thus  fteal- 
ing  our  attention  from  other  objects,  whilft  by  their  continued 
reiterations  they  become  familiar  themfelves,  and  we  ceafe  grad- 
ually to  attend  to  any  thing,  and  fleep  enfues. 

2.  After  great  fatigue  or  inanition,  \\  h  n  the  ftomach  is  fud- 
Jenly  filled  with  flefh  and  vegetable  food,  the  inattention  to  ex- 
ternal 


jpa  OF  DRUNKENNESS.        SECT.  XXL  3. 

ternal  ftimuli,  and  the  reveries  of  imagination,  become  fo  confpio 
ous  as  to  amount  to  a  degree  of  intoxication.  The  fame  is  at  any 
time  produced  by  fuperadding  a  little  wine  or  opium  to  our  com- 
mon meals  ;  or  by  taking  thefe  feparately  in  confiderable  quan- 
tity ;  and  this  more  efficaciouily  after  fatigue  or  inanition  ;  be- 
caufe  a  lefs  quantity  of  any  ftimulating  material  will  excite  an 
organ  into  energetic  a£lion,  after  it  has  lately  been  torpid  from 
defeft  of  ftimulus  ;  as  objects  appear  more  luminous,  after  we 
•  have  been  in  the  dark  ;  and  becaufe  the  fufpenfion  of  volition, 
which  is  the  immediate  caufe  of  fleep,  is  fooner  induced,  after  a 
continued  voluntary  exertion  has  in  part  exhaufted  the  fenforial 
power  of  volition  ;  in  the  fame  manner  as  we  cannot  contract 
a  {ingle  mufcle  long  together  without  intervals  of  inaftion. 

3.  In  the  beginning  of  intoxication  we  are  inclined  to  fleep, 
as  mentioned  above,  but  by  the  excitement  of  external  circum- 
Itances,  as  of  noife,  light,  bufinefs,  or  by  the  exertion  of  volition, 
we  prevent  the  approaches  of  it,  and  continue  to  take  into  our 
itomach  greater  quantities  of  the  inebriating  materials.  By  thefe 
means  the  irritative  movements  of  the  ftomach  are  excited  into 
greater  action  than  is  natural ;  and  in  confequence  all  the  irrita- 
tive tribes  and  trains  of  motion,  which  are  catenated  with  them, 
become  fufceptible  of  ilronger  action  from  their  accuftomed 
ftimuli  ;  becaufe  thefe  motions  are  excited  both  by  their  ufual 
irritation,  and  by  their  aflbciation  with  the  increafed  aftions  of 
the  (tomach  and  lacteals.  Hence  the  (kin  glows,  and  the  heat 
of  the  body  is  increafed,  by  the  more  energetic  action  of  the 
whole  glandular  fyftem ;  and  pleafure  is  introduced  in  confe- 
quence of  thefe  increafed  motions  from  internal  ftimulus.  Ac- 
cording to  Law  5.  Sect.  IV.  on  Animal  Caufation. 

From  this  great  increafe  of  irritative  motions  from  internal 
ftimulus,  and  the  increafed  fenfation  introduced  into  the  fyftem 
in  confequence  ;  and  fecondly,  from  the  increafed  fenfitive  mo- 
tions in  confequence  of  this  additional  quantity  of  fenfation,  fo 
much  fenforial  power  is  expended,  that  the  voluntary  power  be- 
comes feebly  exerted,  and  the  irritation  from  the  ftimulus  of  ex- 
ternal objects  is  lefs  forcible  ;  the  external  parts  of  the  eye  are 
not  therefore  voluntarily  adapted  to  the  diftances  of  objects, 
whence  the  apparent  motions  of  thofe  objects  either  are  feen 
double,  or  become  too  indiftinct  for  the  purpofe  of  balancing 
the  body,  and  vertigo  is  induced 

Hence  we  become  acquainted  with  that  very  curious  circum- 
ftance,  why  the  drunken  vertigo  is  attended  with  an  increafe  of 
pleafure  ;  for  the  irritative  ideas  arid  motions  occafioned  by  in- 
ternal ftimulus,  that  were  not  attended  to  in  our  fober  hours, 
are  now  juft  fo  much  increafed  as  to  be  fucceeded  by  pleafurable 

'fenfation, 


SECT.  XXL  4.  OF  DRUNKENNESS.  m 

fenfation,  in  the  fame  manner  as  the  more  violent  motions  of  our 
organs  are  lucceeded  by  painful  fenfation.  And  hence  a  greater 
quantity  of  pleafurable  fenfation  is  introduced  into  the  conftitu  • 
tion  ;  which  is  attended  in  fome  people  with  an  increafe  of  be- 
nevolence and  good  humour. 

If  the  apparent  motions  of  objects  is  much  increafed,  as  when 
we  revolve  on  one  foot,  or  are  fwung  on  a  rope,  the  ideas  of 
thefe  apparent  morions'  are  alfo  attended  to,  and  are  fucceeded 
with  pleaiurable  fenfation,  till  they  become  familiar  to  us  by  fre- 
quent ufe.  Hence  children  are  at  firit  delighted  with  thefe 
kinds  of  exercife,  and  with  riding,  and  failing,  and  hence  rock- 
ing young  children  inclines  them  to  fleep  For  though  in  the 
vertigo  from  intoxication  the  irritative  ideas  of  the  apparent  mo- 
tions of  objects  are  indiilintt  from  their  decreafe  of  energy  :  yet 
in  the  vertigo  occafio><ed  by  rocking  or  fwinging  the  irritative 
ideas  of  ihe  apparent  motions  of  objecls  are  increafed  in  energy, 
and  hence  they  induce  pleafure  imo  the  fyltcm  but  are  equally 
indittmct,  and  in  confequence  equally  unfit  to  balance  ourldves 
by.  This  addition  of  pleafure  precludes  defire  or  averfion,  and 
in  confequence  the  voluntary  power  is  feebly  exerted,  an  ;  on 
this  account,  rocking  young  children  inclines  them  to  deep. 

In  what  manner  opium  and  wine  act  in  relieving  pain  is 
another  article,  that  well  deferves  our  attemion.  There  are 
many  pains  that  originate  from  defect  as  well  as  from  extefs  of 
ftimulus  j  of  thefe  are  thofe  of  the  fix  appetit'-s  of  hunger,  thirft, 
lull,  the  want  of  heat,  of  detention,  and  of  frefli  air.  Thus  if 
our  cutaneous  capillaries  ceafe  to  act  from  the  diminifhed  ftirnu- 
lus  of  heat,  when  we  arr  expofed  to  cold  weather,  or  our  ftom- 
ach  is  uneafy  for  want  of  food  ;  thefe  are  both  pains  from  defect 
of  Itimulus,  and  in  cunfequence,  opium,  which  ftimulates  all  the 
moving  fyttem  into  increafed  action,  muit  relieve  them.  But 
this  is  not  the  cafe  in  rhofe  pains,  which  ariie  from  excefs  of 
ftimulus,  as  in  violent  inflammations  :  in  thefe  the  exhibition  of 
opium  is  frequently  injurious  by  increafing  the  action  of  the 
fyftrra  already  too  great,  as  in  inflammations  of  the  bowels  mor- 
tific  tion  is  of:  en  produced  by  the  ftimulus  of  opium.  Where, 
however  no  fuch  Dad  confequences  follow  ;  the  ftimulus  of  opi- 
um, by  increafing  all  the  motions  of  [he  fyftem,  expends  fo  much 
of  the  fenforiai  power,  that  the  actions  of  the  whole  fydem  foon 
become  feebler,  and  in  confequence  thofe  which  produced  the 
pain  and  inflammation. 

4  When  intoxication  proceeds  a  little  further,  the  quantity 
of  pleafurable  fenfation  is  fo  far  increafed,  that  all  defire  ceafes, 
foi  there  is  is  no  pain  in  the  fyiiem  to  excite  it.  Hence  the  vol- 
untary exertions  are  diminiChed,  ftaggering  and  Hammering  fuc- 

VOL.  I.  BE  ceed ; 


194  OF  DRUNKENNESS.          SECT.  XXL  5. 

ceed  ;  and  the  trains  of  ideas  become  more  and  more  inconfift- 
ent  from  this  defect  of  voluntary  exertion,  as  explained  in  the 
fections  on  fleep  and  reverie,  whilft  thofe  paffions  which  are  un- 
mixed with  volition  are  more  vividly  felt,  and  (hewn  with  lefs 
referve  ;  hence  pining  love,  or  fuperftitious  fear,  and  the  maud- 
iing  tear  dropped  on  the  remembrance  of  the  mod  trifling 
diftrefs. 

5.  At  length  all  thefe  circumftances  are  increafed  ;  the  quan- 
tity of  pleafure  introduced  into  the  fyftem  by  the  increafed  irrita- 
tive mufcular  motion  of  the  whole  fanguiferous,  and  glandular, 
and  abforbent  fyflems,  becomes  fo  great,  that  the  organs  of  fenfe 
are  more  forcibly  excited  into  action  by  this  internal  pleafurable 
fenfation,  than  by  the  irritation  from  the  ftimulus  of  external 
objects.     Hence  the  drunkard  ceafes  to  attend  to  external  ftimu- 
li,  and  as  volition  is  now  alfo  fufpended,  the  trains  of  his  ideas 
become  totally  inconfiflent  as  in  dreams,  or  delirium  :  and   at 
length  a  ftupor  fucceeds  from  the  great  exhauftion  of  fenforial 
power,  which  probably  does  not  even  admit  of  dreams,  and  in 
which,  as  in  apoplexy,  no  motions  continue  but  thofe  from  in- 
ternal ftimuli,  from  fenfation,  and  from  aflbciation. 

6.  In  other  people  a  paroxyfm  of  drunkennefs  has  another  ter- 
mination ;  the  inebriate,  as  foon  as  he  begins  to  be  vertiginous, 
makes  pale  urine  in  great  quantities  and  very  frequently,  and  at 
length  becomes  lick,  vomits  repeatedly,  or  purges,  or  has  pn> 
fufe  fweats,  and  a  temporary  fever  enfues  with  a  quick  ftrong 
pulfe.     This  in  fome  hours  is  fucceeded  by  fleep  ;  but  the  un- 
fortunate bacchanalian  does  not  perfectly  recover  himfelf  till 
about  the  fame  time  of  the  fucceeding  day,  when  his  courfe  of 
inebriation  began.     As  fhewn  in  Sect.  XVII.  I.  7,  on  Catena- 
tion.    The  temporary  fever  with  ftrong  pulfe  is  owing  to  the 
fame  caufe  as  the  glow  on  the  fkin  mentioned  in  the  third  para- 
graph of  this  Section  :  the  flow  of  urine  and  ficknefs  arife  from 
the  whole  fyftem  of  irritative  motions  being  thrown  into  confu- 
fion  by  their  aflbciations  with  each  other  as  in   fea-ficknefs, 
mentioned  in  Sect,  XX.  4.  on  Vertigo  •,  and  which  is  more  fully 
explained  in  Section  XXIX.  on  Diabetes. 

7.  In  this  vertigo  from  internal  caufes  we  fee  objects  double, 
as  two  candles  inftead  of  one,  which  is  thus  explained.     Two 
lines  drawn  through  the  axis  of  our  two  eyes  meet  at  the  object 
we  attend  to  :  this  angle  of  the  optic  axi.s  increafes  or  diminifhes 
with  the  lefs  or  greater  diftances  of  objects.     All  objects  before 
or  behind  the  place  where  this  angle  is  formed,  appear  double ; 
as  any  one  may  obferve  by  holding  up  a  pen  between  his  eyes 
and  the  candle ;  when  he  looks  attentively  at  a  fpot  on  the  pen, 
and  careiefsly  at  the  candle,  it  will  appear  double  $  and  the  re- 

verfe 


SECT.  XXI.  8.  OF  DRUNKENNESS.  195 

verfe  when  he  looks  attentively  at  the  candle  and  carelefsly  at 
the  pen  ;  fo  that  in  this  cafe  the  mufcles  of  the  eye,  like  thofe 
of  the  limbs,  ftagger  and  are  difobedient  to  the-'expiring  efforts 
of  volition.  Numerous  objects  are  indeed  fometimes  feen  by 
the  inebriate,  occafioned  by  the  refractions  made  by  the  tears, 
which  (land  upon  his  eye-lids. 

8.  This  vertigo  alfo  continues,  when  the  inebriate  lies  in  his 
bed,  inithe  dark,  or  with  his  eyes  clofed ;  and  this  more  power- 
fully than  when   he   is  erect,  and  in  the  light.     For  the  irrita- 
tive ideas  of  the  apparent  motions  of  objects  are  now  excited  by 
irritation  from  internal  ftimulus,'  or  by  aflbciation  with  other 
irritative  motions  j  and  the  inebriate,  like  one  in  a  dream,  be- 
lieves the  objects  of  thefe  irritative  motions  to  be  prefent,  and 
feels  himfelf  vertiginous.     1  have  obferved  in  this  fituation,  fo 
long  as  my  eyes  and  mind  were  intent  upon  a  book,  the  fick- 
nefs  and  vertigo  ceafed,  and  were  renewed  again  the  moment  I 
difcontinued  this  attention  ;  as  was  explained  in  the  preceding 
account   of   fea-ficknefs.      Some   drunken   people   have   been 
known  to  become  fober  inftantly  from  fome  accident,  that  has 
ftrongly  excited  their  attention,  as  the  pain  of  a  broken  bone,  or 
the  news  of  their  houfe  being  on  fire. 

9.  Sometimes  the  vertigo  from  internal  caufes,  as  from  in- 
toxication, or  at  the  beginning  of  fome  fevers,  becomes  fo  univer- 
fal,  that  the  irritative  motions  which  belong  to  other  organs  of 
fenfe  are  fucceeded  by  fenfation  or  attention,  as  well  as  thofe  of 
the  eye.     The  vertiginous  noife  in  the  ears  has  been  explained 
in  Section  XX.  on  Vertigo.     The  tafte  of  the  faliva  which  in 
general  is  not  attended  to,  becomes  perceptible,  and  the  patients 
complain  of  a  bad  tafte  in  their  mouth. 

The  common  fmells  of  the  furrounding  air  fometimes  excite 
the  attention  of  thefe  patients,  and  bad  fmells  are  complained  of, 
which  to  other  people  are  imperceptible.  The  irritative  mo- 
tions that  belong  to  the  fenfe  of  preflure,  or  of  touch,  are  attend- 
ed to,  and  the  patient  conceives  the  bed  to  librate,  and  is  fear- 
ful of  falling  out  of  it.  The  irritative  motions  belonging  to  the 
fenfes  of  diftention,  and  of  heat,  like  thofe  above  mentioned, 
become  attended  to  at  this  time  ;  hence  we  feel  the  pulfation  of 
our  arteries  all  over  us,  and  complain  of  heat,  or  of  cold,  in 
parts  of  the  body  where  there  is  no  accumulation  or  diminution  of 
actual  heat.  All  which  are  to  be  explained,  as  in  the  laft  para- 
graph, by  the  irritative  ideas  belonging  to  the  various  fenfes  be- 
ing now  excited  by  internal  ftimuli,  or  by  their  aflbciations 
with  other  irritative  motions.  And  that  the  inebriate,  like 
one  in  a  dream,  believes  the  external  objects,  which  ufually 
caufed  thefe  irritative  ideas,  to,  be  now  prefent. 

10.  Thfe 


i96  OF  DRUNKENNESS.       SECT.  XXI.  10. 

10.  The  difeafes  in  confequence  of  frequent  inebriety,  or  of 
daily  taking  much  vinous  ipirit  without  inebriety,  confift  in  the 
paralyfis,  which  is  liable  to  fucceed  violent  ftimulation.  Or- 
gans, whofe  aftions  are  aflbciated  with  others,  are  frequently 
more  affected  than  the  organ,  which  is  ftimulated  into  too  vio- 
lent action.  See  Seft.  XXIV.  2.  8.  Hence  in  drunken  people 
it  generally  happens,  that  the  fecretory  veifels  of  the  liver  be- 
come firft  paralytic,  and  a  torpor  with  confequent  gall-ftones 
or  fcirrhus  of  this  vifcus  is  induced  with  concomitant  jaundice  ; 
otherwife  it  becomes  inflamed  in  confequence  of  previous  tor- 
por, and  this  inflammation  is  frequently  transferred  to  a  more 
fenfible  part,  which  is  aflbciated  with  it,  and  produces  the  gout, 
or  the  rofy  eruption  of  the  face,  or  fome  other  leprous  eruption 
on  the  head,  or  arms,  or  legs.  Sometimes  the  ftomach  is  firft 
afredled,  and  paralyfis  of  the  lacleal  fyftem  is  induced :  whence 
a  total  abhorrence  from  flefh-food,  and  general  emaciation.  In 
others  the  lymphatic  fyftem  is  affected  with  paralyfis,  and  drop- 
fy  is  the  confequence.  In  fome  inebriates  the  torpor  of  the  liv- 
er produces  pain  without  apparent  fcirrhus,  or  gall-ftones,  or  in- 
flammation, or  confequent  gout,  and  in  thefe  epilepfy  or  infan- 
ity  are  often  the  confequence.  All  which  will  be  more  fully 
treated  of  in  the  courfe  of  the  work. 

I  am  well  aware  that  it  is  a  common  opinion,  that  the  gout 
is  as  frequently  owing  to  gluttony  in  eating,  as  to  intemperance 
in  drinking  fermented  or  fpirituous  liquors  To  this  I  anfwer, 
that  I  have  feen  no  perfon  afflicled  with  the  gout,  who  has  not 
drunk  freely  of  fermented  liquor,  as  wine  and  water,  or  fmall 
beer ;  though  as  the  di'pofition  to  all  the  difeafes,  which  have  ori- 
ginated from  intoxication,  is  in  fome  degree  hereditary,  a  lefs  quan- 
tity of  fpirituous  potation  will  induce  the  gout  in  thefe,  who  in- 
herit the  difpofition  from  their  parents.  To  which  I  muft  add, 
that  in  young  people  the  rheumatifm  is  frequently  miftaken  for 
the  gout. 

Spice  is  feldom  taken  in  fuch  quantity  as  to  do  any  material 
injury  to  the  fyftem  ;  fleih- meats  as  well  as  vegetables  are  the 
natural  diet  of  mankind  ;  with  thefe  a  glutton  maybe  crammed 
up  to  the  throat,  and  fed  fat  like  a  ftalled  ox  ;  but  he  will  not 
be  di leafed,  unlefs  he  adds  fpirituous  or  fermented  liquor  to  his 
food.  This  is  well  known  in  the  dUtilleries,  where  the  fwine, 
which  are  fattened  by  the  fpirituous  fediments  of  barrels,  acquire 
difeafed  livers.  But  mark  what  happens  to  a  man,  who  drinks 
a  quart  of  wine  or  of  ale,  if  he  has  not  been  habituated  to  it. 
He  lofes  the  ufe  of  both  his  limbs  and  of  his  underltanding  !  He 
becomes  a  temporary  idiot,  and  has  a  temporary  ftroke  of  the 
palfy  !  And  though  he  flowly  recovers  after  fome  hours,  is  it 

not 


SECT.  XXI.  ii.  OF  DRUNKENNESS.  197 

not  reafonabJe  to  conclude,  that  a  perpetual  repetition  of  fo  pow- 
erful a  poifon  mutt  at  length  permanently  affect  him  ? — If  a  per* 
fon  accidentally  becomes  intoxicated  by  eating  a  few  mulhrooms 
of  a  peculiar  kind,  a  general  alarm  is  excited,  and  he  is  laid  to 
be  poifoned,  and  emetics  are  exhibited  ;  but  fo  familiarifed  are 
we  to  the  intoxication  from  vinous  ipirit,  that  it  occafions  laugh- 
ter rather  rhan  alarm. 

There  is  however  confiderable  danger  in  too  haftily  difcontin- 
uing  the  ufe  of  fo  llrong  a  itimulus,  left  the  torpor  of  the  fyftem, 
or  paralyfis,  (hould  fooner  be  induced  by  the  omiflion  than  by 
the  continuance  of  this  habit,  when  unfortunately  acquired.  A 
golden  rule  for  determining  the  quantity,  which  may  with 
fafety  be  discontinued,  is  delivered  in  Seel.  XII  7.  8. 

1 1 .  Definition  of  drunkennefs.  Many  of  the  irritative  motions 
are  much  increafed  in  energy  by  internal  ftimulation. 

2.  A  great  additional  quantity  of  pleafurable  fenfation  is  occa- 
fioned  by  this  increafed  exertion  of  the  irritative  motions.  And 
many  fenfitive  motions  are  produced  in  confequence  of  this  in- 
creafed fenfation. 

3  The  aflbciated  trains  and  tribes  of  motions,  catenated  with 
the  increafed  irritative  and  fenfitive  motions,  are  diiturbed,  and 
proceed  in  confufion. 

4.  The  faculty  of  volition  is  gradually  impaired,  whence  pro- 
ceeds the  instability  of  locomotion,  inaccuracy  of  perception,  and 
inconfiltency  of  ideas  ;  and  is  at  Jcngth  totally  impended,  and  a 
temporajy  apoplexy  fucceeds* 


SECT, 


*9*  REPETITION.  SECT.  XXII.  i,r> 

SECT-      XXII. 

OF   PROPENSITY    TO    MOTION,    REPETITION    AND    IMITATION. 

I.  Accumulation  of  fenforial  power  in  hemiplegia,  injleep,  in  cold  Jit 
of  fever  i  in  the  locomotive  mufcles ,  in  the  organs  of  fenfe.  Produ- 
ces propenftty  to  aclion.  II.  Repetition  by  three  fenforial  powers. 
In  rhymes  and  alliterations  ^  in  mufic>  dancing,  architecture^  land- 
fcape-painting)  beauty*  III.  I.  Perception  confijls  in  imitation. 
Four  kinds  of  imitation.  2.  Voluntary.  Dogs  taught  to  dance.  3. 
Senfttive.  Hence  fympathy^  and  all  our  virtues.  Contagious  matter 
ef  venereal  ulcers  >  of  hydrophobia,  of  jail -fever  >  of fmall-poxy  produ- 
ced by  imitation,  and  the  f ex  of  the  embryon.  4,  Irritative  imita- 
tion. 5.  Imitations  refolvable  into  ajjbciations. 

L  i.  IN  the  hemiplegia,  when  the  limbs  on  one  fide  have 
loft  their  power  of  voluntary  motion,  the  patient  is  for  many 
days  perpetually  employed  in  moving  thofe  of  the  other.  2. 
When  the  voluntary  power  is  fufpended  during  fleep,  there  com- 
mences a  ceafelefs  flow  of  fenfitive  motions,  or  ideas  of  imagin- 
ation, which  compofe  our  dreams.  3.  When  in  the  cold  fit  of 
an  intermittent  fever  fome  parts  of  the  fyftem  have  for  a  time 
coutinued  torpid,  and  have  thus  expended  lefs  than  their  ufual 
expenditure  of  fenforial  power^;  a  hot  fit  fucceeds,  with  violent 
action  of  thofe  vefiels,  which  had  previoufly  been  quiefcent.  All 
thefe  are  explained  from  an  accumulation  of  fenforial  power 
during  the  inactivity  of  fome  part  of  the  fyftem. 

Befidesthe  very  great  quantity  of  fenforial  power  perpetually 
produced  and  expended  in  moving  the  arterial,  venous,  and  glan- 
dular fyftems,  with  the  various  organs  of  digeftion,  as  defcribed 
in  Se£Hon  XXXII.  3.  2.  there  is  alfo  a  conftant  expenditure  of 
it  by  the  aftion  of  our  locomotive  mufcles  and  organs  of  fenfe. 
Thus  the  thicknefs  of  the  optic  nerves,  where  they  enter  the  eye, 
and  the  great  expanfion  of  the  nerves  of  touch  beneath  the  whole 
of  the  cuticle,  evince  the  great  confumption  of  fenforial  power  by 
thefe  fenfes.  And  our  perpetual  mufcular  actions  in  the  com- 
mon offices  of  life,  and  in  conftantly  preferving  the  perpendic- 
ularity of  our  bodies  during  the  day,  evince  a  confiderable  ex- 
penditure of  the  fpirit  of  animation  by  our  locomotive  mufcles. 
It  follows  that  if  the  exertion  of  thefe  organs  of  fenfe  and  muf- 
cles be  for  a  while  intermitted,  that  fome  quantity  of  fenforial 
power  muft  be  accumulated,  and  a  propenfity  to  activity  of  fome 
kind  enfue  from  increafed  excitability  of  the  fyftem.  Whence 

proceeds 


SECT.  XXII.  2.  i.        AND  IMITATION.  199 

proceeds  the  irkfomnefs  of  a  continued   attitude,  and  of  an  in- 
dolent life. 

However  fmall  this  hourly  accumulation  of  the  fpirit  of  ani- 
mation may  be,  it  produces  a  propenfity  to  fome  kind  of  action  j 
but  it  neverthelefs  requires  either  defire  or  averfion,  either  pleaf- 
ure  or  pain,  or  fome  external  ftimulus,  or  a  previous  link  of  af- 
fociation,  to  excite  the  fyftem  into  activity  ;  thus  it  frequently 
happens,  when  the  mind  and  body  are  fo  unemployed  as  not  to 
poffefs  any  of  the  three  firft  kinds  of  ftimuli,  that  the  laft  takes 
place,  and  confumes  the  fmall  but  perpetual  accumulation  of  fen- 
forial power.  Whence  fome  indolent  people  repeat  the  fame 
verfe  for  hours  together,  or  hum  the  fame  tune.  Thus  the  poet: 

Onward  he  trudged,  not  knowing  what  he  fought 
And  whiftled  as  he  went,  for  want  of  thought. 

II.  The  repetitions  of  motions  may  be  at  firft  produced  either 
fay  volition,  or  by  fenfation,  or  by  irritation,  but  they  foon  become 
eafier  to  perform  than  any  other  kinds  of  action,  becaufe  they 
foon  become  afibciated  together,  according  to  Law  the  feventh, 
Section  IV.  on  Animal  Caufation.  And  becaufe  their  fre- 
quency of  repetition,  if  as  much  fenforial  power  be  produced  du- 
ring every  reiteration  as  is  expended,  adds  to  the  facility  of 
their  production. 

If  a  ftimulus  be  repeated  at  uniform  intervals  of  time,  as  de- 
fcribed  in  Sect.  XII.  3.  3.  the  action,  whether  of  our  mufcles  or 
organs  of  fenfe,  is  produced  with  ftill  greater  facility  or  energy ; 
becaufe  the  fenforial  power  of  aflbciation,  mentioned  above,  is 
combined  with  the  fenforial  power  of  irritation ;  that  is,  in  com- 
mon language,  the  acquired  habit  aflifts  thepower  of  the  ftimulus. 

This  not  only  obtains  in  the  annual,  lunar,  and  diurnal  catena- 
tions of  animal  motions,  as  explained  in  Sect  XXXVI.  which 
are  thus  performed  with  great  facility  and  energy  ;  but  in  every 
lefs  circle  of  actions  or  ideas,  as  in  the  burthen  of  a  fong,  or  the 
reiterations  of  a  dance.  To  the  facility  and  diftinctnefs,  with 
which  we  hear  founds  at  repeated  intervals,  we  owe  thepleafure, 
which  we  receive  from  mufical  time,  and  from  poetic  time  j  as 
defcribedin  Botanic  Garden,  P.  2.  Interlude  3.  And  to  this 
the  pleafure  we  receive  from  the  rhymes  and  alliterations  of  mod- 
ern verfification  ;  the  fource  of  which  without  this  key  would 
be  difficult  to  difcover.  And  to  this  likewife  (hould  be  aicribed 
the  beauty  of  the  duplicature  in  the  perfect  tenfe  of  the  Greek 
verbs,  and  of  fome  Latin  ones,  as  tango  tetegi,  mordeo  momordi. 

There  is  no  variety  of  notes  referable  to  the  gamut  in  the 
beating  of  the  drum,  yet  if  it  be  performed  in  mufical  time,  it  is 

agreeable 


REPETITION  SECT.  XXII.  2.  r. 

agreeable  to  our  ears  ;  and  therefore  this  pleafurable  fenfation 
muft  be  owing  to  the  repetition  of  the  divifions  of  the  founds  at 
certain  intervals  of  time,  or  mufical  bars.  Whether  thgfe  times 
or  bars  are  dittinguifhed  by  a  paufe,or  by  an  emphafis,  or  accent, 
certain  it  is,  thafrthis  diftinftion  is  perpetually  repeated  ;  other- 
wife  the  ear  could  not  determine  inftantly,  whether  the  fuccef- 
fions  of  found  were  in  common  or  in  triple  timev  In  common 
time  there  is  a  diviu'on  between  every  two  crotchets,  or  other 
notes  of  equivalent  time  •,  though  the  bar  in  written  mufic  is  put 
after  every  fourth  crotchet,  or  notes  equivalent  in  time  ;  in  triple 
time  the  divifion  or  bar  is  after  every  three  crotchets  or  notes 
equivalent ;  fo  that  in  common  time  the  repetition  recurs  more 
frequently  than  in  triple  time.  The  grave  or  heroic  verfes  of 
the  Greek  and  Latin  poets  are  written  in  common  time  ;  the 
French  heroic  verfes,  and  Mr  Anftie's  humorous  verfes  in  his 
Baih  Guide,  are  written  in  the  fame  time  as  the  Greek  and  Lat- 
in verfes,  but  are  one  bar  (horter.  The  Englilh  grave  or  heroic 
verfes  are  meafured  by  triple  time,  as  Mr.  Pope's  tranflation  of 
Homer, 

But  befides  thefe  little  circles  of  mufical  time,  there  are  the 
greater  returning  periods,  and  the  dill  more  diftant  chorufTes, 
which,  like  the  rhymes  at  the  ends  of  verfes,  owe  their  beauty 
to  repetition  ;  that  is,  to  the  facility  and  diftincftnefs  with  which 
we  perceive  founds,  which  we  expe£t  to  perceive,  or  have 
perceived  before  •,  or,  in  the  language  of  this  wt>rk,  to  the  great- 
er eafe  and  energy  with  which  our  organ  is  excited  by  the  com- 
bined feniorial  powers  of  aflbciation  and  irritation,  than  by  the 
latter  fingly. 

A  certain  uniformity  or  repetition  of  parts  enters  the  very  com- 
pofition  of  harmony.  Thus  two  oftaves  neareft  to  each  other 
in  the  fcale  commence  their  vibrations  together  after  every  fec- 
ond  vibration  of  the  higher  tone.  And  uhere  the  firil,  third, 
and  fifth  compofe  a  chord  the  vibrations  concur  or  coincide  fre- 
quently, though  lefs  fo  than  in  the  two  odaves.  It  is  probable 
that  thefe  chords  bear  ibrne  analogy  to  a  mixture  of  three  alter- 
nate colours  in  the  fun's  fpedtrurn  feparated  by  a  prifm. 

The  pleafure  we  receive  from  a  melodious  fucceiTien  of  notes 
referable  to  the  gamut  is  derived  from  another  fource,  viz  to  the 
pandiculation  or  counteraction  of  antagonift  fibres  See  Botan- 
ic Garden,  P.  2.  Interlude  3.  If  to  thefe  be  added  our  early  af~ 
ibciations  of  agreeable  ideas  with  certain  proportions  of  found, 
I  fuppofe,  from  thefe  three  fources  fpring  all  the  delight  of  mu- 
fic, fo  celebrated  by  ancient  authors,  and  fo  enthufiaftically  cul- 
tivated at  prefent.  See  Se£t.  XVI.  No.  10.  on  Inftinch 

This  kind  of  pleafure  anfing  from  repetition,  that  is,  from  the 

facility 


•Steer.  XXII.  3.  i.      AND  IMITATION.  201 

facility  and  diftindlnefs,  with  which  we  perceive  and  underftand 
repeated  fenfations,  enters  into  all  the  agreeable  arts  $  and  when 
it  is  carried  to  excefs  is  termed  formality.  The  art  of  dancing  like 
that  of  mufic  depends  for  a  great  part  of  the  pleafure  it  affords, 
on  repetition  ;  architecture,  efpecially  the  Grecian,  confiits  of 
one  part  being  a  repetition  of  another  ;  and  hence  the  beauty  of 
the  pyramidal  outline  in  iandfcape-painting  ;  where  one  fide  of 
the  picture  may  be  faid  in  fome  meafure  to  balance  the  other. 
So  univerfally  does  repetition  contribute  to  our  pleafure  in  the 
fine  arts,  that  beauty  itfelf  has  been  defined  by  fome  writers  to 
eonfift  in  a  due  combination  of  uniformity  and  variety.  See 
Sea.  XVI.  6. 

111.  i.  Man  is  termed  by  Ariftotle  an  imitative  animal ;  this 
propenfity  to  imitation  not  only  appears  in  the  actions  of  children, 
but  in  all  the  cuftoms  and  fafhions  of  the  world  :  many  thou- 
fands  tread  in  the  beaten  paths  of  others,  for  one  who  traverfes 
regions  of  his  own  difcovery.  The  origin  of  this  propenfity  of 
imitation  has  not,  that  I  recollect,  been  deduced  from  any  known 
principle  ;  when  any  action  prefents  itfelf  to  the  view  of  a  child, 
as  of  whetting  a  knife,  or  threading  a  needle,  the  parts  of  this  ac- 
tion in  refpect  of  time,  motion,  figure,  are  imitated  by  a  part  of 
the  retina  of  his  eye  ;  to  perform  this  action  therefore  with  his 
hands  is  eafier  to  him  than  to  invent  any  new  action,  becaufe 
it  confifts  in  repeating  with  another  fet  of  fibres,  viz.  wi:h  the 
moving  mufcles,  what  he  has  juit  performed  by  fome  parrs  of 
the  retina  ;  juft  as  in  dancing  we  transfer  the  times  of  motion 
from  the  actions  of  the  auditory  nerves  to  the  mufcles  of  che  limbs. 
Imitation  therefore  confifts  of  repetition,  which  we  have  {hewn 
above  to  be  the  eafieft  kind  of  animal  action,  and  which  we  per- 
petually fall  into,  when  we  poffefs  an  accumulation  of  fenfuriai. 
power,  which  is  not  otherwife  called  into  exertion. 

It  has  been  (hewn  that  our  ideas  are  configurations  of  the  or- 
gans of  fenfe,  produced  originally  in  coniequence  of  the  ftimu- 
lus  of  external  bodies.  And  rhat  thefe  ideas,  or  configurations 
of  the  organs  of  fenie,  refemble  in  fome  property  a  correfpond- 
ent  property  of  external  matter  ;  as  the  parts  of  the  fenfes  of 
fight  and  of  touch,  which  are  excited  into  action,  refemble  in 
figure  the  figure  of  the  (limulating  body  ;  and  probably  alib  the 
colour,  and  the  quantity  of  denfity,  which  they  perceive.  As 
explained  in  Sect.  XIV.  2.  2.  Hence  it  appears,  that  our  per-  ^ 
ceptions  themfeives  are  copies,  that  is,  imitations  of  fome  prop- ' 
erties  of  external  matter  ;  and  the  propenfity  to  imitation  is  thus 
interwoven  with  our  exiftence,  as  it  is  produced  by  the  flimuli 
of  external  bodies,  and  is  afterwards  repeated  by  our  volitions 

VOL,  I.  C  c  and 


202  REPETITION  SECT.  XXII.  3. 2- 

and  fenfations,  and  thus  conftitutes  all  the  operations  of  our 
minds. 

2  Imitations  refolve  themfelves  into  four  kinds,  voluntary, 
fenfitive,  irritative,  and  affociate.  The  voluntary  imitations  are, 
when  we  imitate  deliberately  the  actions  of  others,  either  by 
mimicry,  as  in  a&ing  a  play,  or  in  delineating  a  flower ;  or  in 
the  common  actions  of  our  lives,  as  in  our  drefs,  cookery,  lan- 
guage, manners,  and  even  in  our  habits  of  thinking. 

Not  only  the  greateft  part  of  mankind  learn  all  the  common 
arts  of  life  by  imitating  others,  but  brute  animals  feem  capable 
of  acquiring  knowledge  with  greater  facility  by  imitating  each 
other,  than  by  any  methods  by  which  we  can  teach  them ;  as 
dogs  and  cats  when  they  are  fick,  learn  of  each  other  to  eat 
grafs  ;  and  I  fuppofe  that  by  making  an  artificial  dog  perform 
certain  tricks,  as  in  dancing  on  his  hinder  legs,  a  living  dog 
might  be  eafily  induced  to  imitate  them  ;  and  that  the  readier! 
way  of  inftrucling  dumb  animals  is  by  praclifing  them  with 
others  of  the  fame  fpecies,  which  have  already  learned  the  arts 
we  wifh  to  teach  them.  The  important  ufe  of  imitation  in  ac- 
quiring natural  language  is  mentioned  in  Sedion  XVI.  7.  and 
8.  on  Inftind. 

3.  The  fenfitive  imitations  are  the  immediate  confequences 
of  pleafure  or  pain,  and  thefe  are  often  produced  even  contrary 
to  the  efforts  of  the  will  Thus  many  young  men  on  feeing 
cruel  furgical  operations  become  fick,  and  fome  even  feel  pain 
in  the  parts  of  their  own  bodies,  which  they  fee  tortured  or 
wounded  in  others  ;  that  is,  they  in  fome  meafure  imitate  by  the 
exertions  of  their  own  fibres  the  violent  actions  which  they 
witnefled  in  thofe  of  others.  In  this  cafe  a  double  imitation 
takes  place,  firft  the  obferver  imitates  with  the  extremities  of 
the  optic  nerve  the  mangled  limbs,  which  are  prefent  before  his 
eyes ;  then  by  a  fecond  imitation  he  excites  fo  violent  aclion  of 
the  fibres  of  his  own  limbs  as  to  produce  pain  in  thofe  parts  of 
his  own  body,  which  he  law  wounded  in  another.  In  thefe  pains 
produced  by  imitation  the  effecl  has  fome  fimilarity  to  the  caufe, 
which  diftinguifhes  them  from  thofe  produced  by  affbciation  ; 
as  the  pains  of  the  teeth,  called  tooth-edge,  which  are  produced 
by  aflbciation  with  difagreeable  founds,  as  explained  in  Sec"l. 
XVI.  10. 

The  effect  of  this  powerful  agent,  imitation,  in  the  moral 
world,  is  mentioned  in  Seel.  XVI  7.  as  it  is  the  foundation  of 
all  our  intellectual  fympathies  with  the  pains  and  pleafures  of 
others,  and  is  in  confequence  the  fource  of  all  our  virtues.  For 
in  what  confirls  our  fympathy  with  the  miferies,  or  with  the 
joys,  of  our  fellow  creatures,  but  in  an  involuntary  excitation  of 

ideas 


SECT.  XXII.  3.  3.       AND  IMITATION.  203 

ideas  in  fome  meafure  Cmilar  or  imitative  of  thofe,  which  we 
believe  to  exift  in  the  minds  of  the  perfons,  whom  we  commif- 
erate  or  congratulate  ? 

There  are  certain  concurrent  or  fucceflive  actions  of  fome  of 
the  glands,   or  other  parts  of  the  body,   which  are  poirefTed  of 
fenfation,  which  become  intelligible  from  this  propenfity  to  imU 
tation.     Of  thefe   are  the  production  of  matter  by  the  mem- 
branes of  the  fauces,  or  by  the  fkin,  in  confequence  of  the  vene- 
real difeafe  previoufly  affecting  the  parts  of  generation.     Since 
as  no  fever  is  excited,  and  as  neither  the  blood  of  fuch  patients, 
nor  even  the  matter  from  ulcers  of  the  throat,  or  from  cutane- 
ous ulcers,  will  by  inoculation  produce  the  venereal  difeafe  in 
others,  as  obferved  by  Mr   Hunter,  there  is  reafon  to  conclude, 
that  no  contagious  matter  is  conveyed  thither  by  the  blood-vef- 
fels,  but  that  a  milder  matter  is  formed  by  the  actions  of  the  fine 
veflels  in  thofe  membranes  imitating  each  other.     See  Section 
XXXIII.  2.  9.     In  this  difeafe  the  actions  of  thefe  veflels  pro- 
ducing ulcers,  on  the  throat  and  fkin  are  imperfect  imitations  of 
thofe  producing  chancre,  or  gonorrhoea  j  fince  the  matter  produ- 
ced by  them  is  not  infectious,  while  the  imitative  actions  in  the 
hydrophobia  appear  to  be  perfect  refemblances,  as  they  produce 
a  material  equally  infectious  with  the  original  one,  which  indu- 
ced them. 

The  contagion  from  the  bite  of  a  mad  dog  differs  from  other 
contagious  materials,  from  its  being  communicable  from  other 
animals  to  mankind,  and  from  many  animals  to  each  other  ;  the 
phenomena  attending  the  hydrophobia  are  in  fome  degree  expli- 
cable on  the  foregoing  theory.  The  infectious  matter  does  not 
appear  to  enter  the  circulation,  as  it  cannot  be  traced  along  the 
courfe  of  the  lymphatics  from  the  wound,  nor  is  there  any  fwell- 
ing  of  the  lymphatic  glands,  nor  does  any  fever  attend,  as  oc- 
curs in  the  fmall-pox,  and  in  many  other  contagious  difeafes  ;  yet 
by  fome  unknown  procefs  the  difeafe  is  communicated  from 
the  wound  to  the  throat,  and  that  many  months  after  the  injury, 
fo  as  to  produce  pain  and  hydrophobia,  with  a  fecretion  of  in- 
fectious faliva  of  the  fame  kind,  as  that  of  the  mad  dog,  which 
inflicted  the  wound. 

This  fubject  is  very  intricate. — It  would  appear,  that  by  cer- 
tain morbid  actions  of  the  falivary  glands  of  the  mad  dog,  a  pe- 
culiar kind  of  faliva  is  produced  •,  which  being  inftilled  into  a 
wound  of  another  animal  ftimulates  the  cutaneous  or  mucous 
glands  into  morbid  actions,  but  which  are  ineffectual  in  refpcft 
to  the  production  of  a  fimilar  contagious  material ;  but  the  fali- 
vary glands  by  irritative  fympathy  are  thrown  into  fimilar  action, 

and 


»04  REPETITION          SECT.  XXII.  3.  4. 

and  produce  an  infeftious  faliva   fimilar  to  that  inllilled  into  the 
wound. 

Though  in  many  contagious  fevers  a  material  fimilar  to  that 
which  produced  the  difeafe,  is  thus  generated  by  imitation  ;  yet 
there  are  other  infeftious  materials,  which  do  not  thus  propagate 
themfelves,  but  which  feem  to  a£t  like  flow  poifons.  Of  this 
kind  was  the  contagious  matter,  which  produced  the  jail-fever 
at  the  ailizes  at  Oxford  about  a  century  ago.  Which,  though 
fatal  to  fo  many,  was  not  communicated  to  their  nurtes  or  at- 
tendants. In  thefe  cafes,  the  imitations  of  the  fine  veffels,  as 
above  defcribed,  appear  to  be  imperfea,  and  do  not  therefore 
produce  a  matrer  fimilar  to  that,  which  ftimulates  them  ;  in 
this  circumftance  refembling  the  venereal  matter  in  ulcers  of  the 
throat  or  ikin,  according  to  the  curious  difcovery  of  Mr.  Hun- 
ter above  related,  who  found,  by  repeated  inoculations,  that  it 
would  not  infed.  Hunter  on  Venereal  Difeafe,  Part  vi. 
ch.  i. 

Another  example  of  morbid  imitation  is  in  the  production  of 
a  great  quantity  of  contagious  matter,  as  in  the  inoculated  fmall- 
pox,  from  a  fmall   quantity   of  it  inferted  into  the  arm.     Thefe 
particles  of  contagious  matter  ftimulate  the  extremities  of  the 
fine  arteries  of  the  fkin,  and  caufe  them  to  imitate  the  motions 
by  which  themfelves   were    produced,  and  thus  to  produce  a 
thoufand  fold  of  a  fimilar  material.     As  different  kinds  of  light 
may  be  fuppofed  to  ftimulate  parts  of  the  retina  into  different 
kinds  of  motion,  fo  the  application  of  different  contagious  mat- 
ters may  be   believed  to  ftimulate  the  fine  terminations  of  the 
arterits  into  different  kinds  of  motion,  which  may  form  matters 
fimilar  to  themfelves.     This  is  truly  difficult  to  underftand,  but 
may  be  conceived  to   depend  on  this  circumftance  ;  that  thofe 
matters,  which  ftimulate  other  bodies  into  aclion,  and  the  bod- 
ies thus  ftimulated,  muft   poflefs  fome  common  properties,  as 
fpoken  of  in  Sea.  XIV.  4.     See  Sea.  XXXIII.  2.  6.     Other 
inftances  are  mentioned  in  the  Seaion  on  Generation,  which 
{hew  the  probability,  that  the  extremities  of  the  feminal  glands 
may  imitate  certain  ideas   of  the  mind,  or  aaions  of  the  organs 
of  fenfe,  and  thus  occafion  the  male  or  female  fex  of  the  embry- 
on.     See  Sea.  XXXIX.  6. 

4  We  come  now  to  thofe  imitations,  which  are  not  attended 
with  fenfation.  Of  thefe  are  all  the  irritative  ideas  already  ex- 
plained, as  when  the  retina  of  the  eye  imitates  by  its  aaion  or 
configuration  the  tree  or  the  bench,  which  I  fhun  in  walking  paft 
without  attending  to  them.  Other  examples  of  thefe  irritative 
imitations  are  daily  obfervable  in  common  life  ;  thus  one  yawn-. 
Ifig  perfon  fhall  fet  a  whole  company  a  yawning  j  and  fome  have 

?cquire4 


SECT.  XXII.  3.  5.      AND  IMITATION.  205 


acquired  winking  of  the  eyes  or  impediments  of  fpeech  by  imita-p 
ting  their  companions  without  being  confcious  of  it. 

5.  Befides  the  three  fpecies  of  imitations  above  defcribed  there 
may  be  fome  afTociate  motions,  which  may  imitate  each  other  in 
the  kind  as  well  as  in  the  quantity  of  their  action  ;  but  it  is 
difficult  to  diftinguifh  the  m  from  the  aflbciations  of  motions; 
treated  of  in  Seftion  XXXV.  Where  the  aftions  of  other  per- 
fons  are  imitated  there  can  be  no  doubt,  or  where  we  imitate  a 
preconceived  idea  by  exertion  of  our  locomotive  mufcles,  as 
in  painting  a  dragon  ;  all  thefe  imitations  may  aptly  be  referred 
to  the  fources  above  defcribed  of  the  propensity  to  activity,  and 
the  facility  of  repetition  ;  at  the  fame  time  I  do  not  affirm,  that 
all  rhofe  other  apparent  fenfitive  and  irritative  imitations  may 
not  be  refolvable  into  aflbeiations  of  a  peculiar  kind,  in  which 
certain  diftant  parts  of  fimilar  irritability  qr  fenfibiHty,  and 
which  have  habitually  afted  together,  may  affec"l  each  other  ex- 
aftly  with  the  fame  kinds  of  motion  ;  as  many  parts  are  known 
to  fympathife  in  the  quantity  of  their  motions.  And  that  there- 
fore they  may  be  ultimately  refolvable  into  aflbciations  of  action 
as  defcribed  in  Sett.  XXXV. 


SECT. 


ao6  CIRCULATORY         SECT.  XXIII.  i.  f, 

SECT.      XXIII. 

OF    THE    CIRCULATORY    SYSTEM. 

1.  The  heart  and  arteries  lave  no  antagonijl  mufeles.  Feins  abforb 
the  blood*  propel  it  forwards,  and  diftend  the  heart  ;  contraction  of 
the  heart  diftendt  the  arteries.  Vena  portarum.  II.  Glands  which 
take  their  fluids  from  the  blood  With  long  necks >  andjhort  necks* 
III.  Abforbent  fyftem.  IV.  Heat  given  out  from  glandular  fe~ 
ceetions*  Blood  changes  colour  in  the  lungs  and  in  the  glands  and 
capillaries  V.  Blood  is  ab for  bed  by  veins ,  ar  chyle  by  la&eal  veffe/s9 
othe>  wife  they  could  not  join  their Jlr earns*  IV.  Two  kinds  ofjlim- 
ulu* ,  agreeable  and  difagreeable.  Glandular  appetency.  Glands 
originally  pujjejjed  fenfation* 

I.  i.  We  now  ftep  forwards  to  illuftrate  fome  of  the  phaenom- 
«na  of  difeafes,  and  to  trace  out  their  moft  efficacious  methods 
of  cure  j  and  (hall  commence  the  fubjecl  with  a  ihort  defcrip- 
tion  of  the  circulatory  fyftem. 

As  the  nerves,  whofe  extremities  form  our  various  organs  of 
fenie  and  rnircks,  are  all  joined,  or  communicate,  by  means  of 
the  brain,  for  the  convenience  perhaps  of  the  diftribution  of  a 
fubtile  ethereal  fluui  for  the  purpoie  of  morion  ;  fo  all  thofe 
veflelb  of  the  body,  which  carry  the  grofler  fluids  for  the  purpo- 
fes  of  nutrition,  communicate  with  each  other  by  the  heart. 

The  heart  and  arteries  are  hollow  mufcles,  and  are  therefore 
indued  with  power  of  contraction  in  confequence  of  ftimulust 
like  all  other  mulcular  fibres  ;  but,  as  they  have  no  antagonift 
mufeles,  the  cavities  of  the  vcflels,  which  they  form,  would  re- 
main for  ever  clofed,  after  they  have  contra&ed  themfelves,  un- 
lefs  fome  extraneous  power  be  applied  to  again  diftend  them. 
This  extraneous  power  in  refpecl:  to  the  heart  is  the  current  of 
blood  which  is  perpetually  abibrbed  by  the  veins  from  the  various 
glands  and  capillaries,  and  pufhed  into  the  heart  by  a  power  prob- 
ably very  fimilar  to  that,  which  raifes  the  fap  in  vegetables  in 
the  fpring,  which,  according  to  Dr.  Hale's  experiment  on  the 
ftump  of  a  vine,  exerted  a  force  equal  to  a  column  of  water 
above  twenty  feet  high*  This  force  of  the  current  of  blood  in 
the  veins  is  partly  produced  by  their  abforbent  power,  exert- 
ed at  the  beginning  of  every  fine  ramification  ;  which  may  be 
conceived  to  be  a  mouth  abforbing  blood,  as  the  mouths  of  the 
la&eals  and  lymphatics  abforb  chyle  and  lymph.  And  partly 
by  their  intermitted  compreffion  by  the  pulfations  of  their  gener- 
ally concomitant  arteries  \  by  which  the  blood  is  perpetually  pro- 
pelled 


SECT.  XXIII.  i.  i.  SYSTEM.  207 

pelled  towards  the  heart,  as  the  valves  in  many  veins,  and  the  ab- 
forbent  mouths  in  them  all,  will  not  fufFer  it  to  return. 

The  blood,  thus  forcibly  inje£led  into  the  chambers  of  the 
heart,  diftends  this  combination  of  hollow  mufcles  ;  till  by  the 
ftimuius  of  difbention  they  contract  themfelves  ;  and,  pufhing 
forwards  the  blood  into  the  arteries,  exert  fufficient  force  to 
overcome  in  lefs  than  a  fecond  of  time  the  vis  inertiae,  and  per- 
haps fome  elafticity,  of  the  very  extenfive  ramifications  of  the 
two  great  fyftems  of  the  aortal  and  pulmonary  arteries.  The 
power  neceffary  to  do  this  in  fo  (hort  a  time  muft  be  confidera- 
able,  and  has  been  varioufly  eltimated  by  different  phyfiologifts. 

The  mufcular  coats  of  the  arterial  iyftem  are  then  brought 
into  action  by  the  ftimuius  of  diftention,  and  propel  the  blood 
to'the  mouths,  or  through  the  convolutions,  which  precede  the 
fecretory  apertures  of  the  various  glands  and  capillaries. 

In  the  vefTels  of  the  liver  there  is  no  intervention  of  the  heart ; 
but  the  vena  portaru;n,  which  does  the  office  of  an  artery,  is  dif- 
tended  by  the  blood  poured  into  it  from  the  mefenteric  veins, 
and  is  by  this  diftention  ftimulated  to  contract  itfelf,  and  propel 
the  blood  to  the  mouths  of  the  numerous  glands,  which  com- 
pofe  that  vifcus. 

The  power  of  abforption  in  vegetable  roots  was  (hewn  by  the 
experiments  of  Dr.  Hales  on  vine-ftumps  to  be  equal  to  the  pref- 
fure  of  thirty-eight  inches  of  quickfilver.  Veg.  Staticks,  p.  107. 
and  from  the  experiments  of  Mr.  Cooper,  who  tied  the  thoracic 
dirts  of  living  dogs,  it  appeared,  that  the  abforbent  power  of  the 
lacteals  and  lymphatics  always  burll  the  receptaculum  chyli.  Mr. 
Cooper  adds,  "  The  contractile  powers  of  the  abforbents  are 
proved  by  thefe  experiments  to  be  very  ftrong  ;  for  it  appears, 
that  their  action  is  fufficient  to  occafion  a  rupture  of  their  coats. 
It  is  true,  that  the  receptaculum  chyli,  which  was  the  part  bro- 
ken, is  thinner  and  lefs  capable  of  refiftance  than  the  thoracic 
duwt  ;  yet  it  is  able  to  bear  the  preflure  of  a  column  of  quick- 
(ilver  more  than  two  feet  in  height.  The  force  therefore  exert- 
ed by  the  abforbents  muft  be  acknowledged  to  be  greater  than 
that  of  fuch  a  column  of  mercury  ;  more  efpecially  when  it  is 
remembered,  that  living  parts  will  refift  a  force,  which  will 
readily  tear  them  when  dead."  Medical  Refearches.  Lon- 
don. 1798,  p,  no. 

Dr  Hales  made  experiments  (imilar  to  thofe  on  the  flumps 
of  vines  above  mentioned,  by  opening  the  crural  arteries  of  a 
horfe,  a  dog,  and  a  fallow  deer,  by  applying  mercurial  guages  to 
meaiure  the  projectile  impetus  of  their  blood  ;  and  found  that  of 
the  vine  (lump  to  be  five  times  greater  than  the  force  of  the 
blood  in  the  great  crural  artery  of  a  horfe,  feven  times  greater 

than 


208  CIRCULATORY.        SECT.  XXIII.  2.  i. 

than  that  of  a  dog,  and  eight  times  greater  than  that  of  a  fallow 
doe. 

The  power  of   abforption  in  the  animal  fyftem  exerts  a  force 
fuperior  to  that  of  the  heart,  though  perhaps  with  lefs  velocity  j 
and  thus  removes  all  difficulty  of  accounting  for  the  circulation 
in  the  veins  and  abibrbents  ;  and  confcquently  of  the  circulation 
in  the  aortal   arteries  of   fifh,  and  in  the  vena  portarum,  or  the 
bile-fecreting  artery  of  the  liver  of  quadrupeds 

II.  i.  The  glandular  fyftem  of  vefTels  may  be  divided  into  thofe, 
which  take  fome  fluid  from  the  circulation  •,  and  thofe,  which 
give  fomething  to  it.  Thofe,  which  take  their  fluid  from  the  cir- 
culation, are  the  various  glands,  by  which  the  tears,  bile,  urine, 
perfpirations,  and  many  other  fecretions  are  produced  ;  fhefe 
glands  probably  confift  of  a  mouth  to  feletr,,  a  belly  to  digeft,  and 
an  excretory  aperture  to  emit  their  appropriated  fluids  ;  the 
blood  is  conveyed  by  the  power  of  the  heart  and  arteries  to  the 
mouths  of  thefe  glands,  it  is  there  taken  up  by  the  living  power 
of  the  glands,  and  carried  forwards  to  its  belly,  and  excretory  ap- 
erture, where  a  part  is  feparated,  and  the  remainder  abforbed 
by  the  veins  for  further  purpofes. 

Some  of  thefe  glands  are  f  urniflied  with  long  convoluted  necks 
or  tubes,  as  the  feminal  ones,  which  are  curioufly  feen  when 
injected  with  quickfilver.  Others  feem  to  confiib  of  (horter 
tubes,  as  that  great  congeries  of  glands,  which  conftitute  the  liv- 
er, and  thofe  of  the  kidneys.  Some  have  their  excretory  aper- 
tures opening  into  refervoirs,  as  the  urinary  and  gall-bladders. 
And  others  on  the  external  body,  as  thofe  which  fecrete  the 
tears,  and  perfpirable  matter. 

Another  great  fyftem  of  glands,  which  have  very  (hort  necks, 
are  the  capillary  veflels  ;  by  which  the  infenfible  perforation  is 
fecreted  on  the  fkin  ;  and  the  mucus  of  various  confidences, 
which  lubricates  the  interftices  of  the  cellular  membrane,  of  the 
mufcular  fibres,  and  of  all  the  larger  cavities  of  the  body.  From 
the  want  of  a  long  convolution  of  veflels  fome  have  doubted 
whether  thefe  capillaries  mould  be  confidered  as  glands  and 
have  been  led  to  conclude,  that  the  perfpirable  matter  rather  ex- 
uded than  was  fecreted.  But  the  fluid  of  perfpiration  is  not  fim- 
ple  water,  though  that  part  of  it,  which  exhales  into  the  air  may 
be  fuch  \  for  there  is  another  part  of  it,  which  in  a  ftate  of  health 
is  abforbed  again  ;  but  which,  when  the  abforbents  are  difeaied 
remains  on  the  furface  of  the  fkin,  in  the  form  of  fcurf,  or  indu- 
rated mucus.  Another  thing,  which  (hews  their  fimilitude  to 
other  glands,  is  their  fenfibility  to  certain  affecHons  of  the  mind  ; 
as  is  feen  in  the  deeper  colour  of  the  fkin  in  the  blufh  of  fhame, 
or  the  greater  palenefs  of  it  from  fear. 

Ill,  Another 


SECT.  XXIII.  3.  SYSTEM.  209 

III.  Another  feries  of  glandular  veflels  is  called  the  abforbent 
fyitem  ;  thefe  open  their  mouths  into  all  the  cavities,  and  upon 
all  thofe  furfaces  of  the  body,  where  the  excretory  apertures  of 
the  other  glands  pour  out  their  fluids.  The  mouths  of  the  ab- 
forbent  fyftem  drink  up  a  part  or  the  whole  of  thefe  fluids,  and 
carry  them  forwards  by  their  living  power  to  their  refpeclive 
glands,  which  are  called  conglobate  glands.  There  thefe  fluids 
undergo  fome  change,  before  they  pafs  on  into  the  circulation  ; 
but  if  they  are  very  acrid,  the  conglobate  glands  fwell,  and  fome 
times  fuppurate,  as  in  inoculation  of  the  fmall  pox,  in  the  plague 
and  in  venereal  abforptions  ;  at  other  times  the  fluid  may  per- 
haps continue  there,  till  it  undergoes  fome  chemical  change  that 
renders  it  lefs  noxious ;  or,  what  is  more  likely,  till  it  is  regurgi- 
tated by  the  retrograde  motion  of  the  gland  in  fpontaneous  fweats 
or  diarrhoeas,  as  difagreeing  food  is  vomited  from  the  ftomach. 
The  powers?of  abforption  are  (hewn  in  No.  I.  of  this  Se&ion, 
both  thofe  of  the  blood  and  of  the  chyle  of  animals,  and  of  the 
fap-juice  of  vegetables,  to  be  much  greater  than  has  comonly 
been  conceived.  To  which  may  be  added,  that  the  moving 
force  of  the  chyle  in  the  receptaculum  chyli  and  thoracic  duel: 
mud  be  equal  to  the  moving  force  of  the  blood  in  the  fubclavian 
vein,  as  otherwife  the  chyle  could  not  enter  into  that  vein,  un- 
lefs  it  be  fuppofed  to  poflefs  a  fyftole  and  diaftole  near  the  heart ; 
which  alfo  affords  an  argument  to  (hew,  that  the  progrefs  of  the 
blood  in  the  veins,  and  that  of  the  chyle  in  the  abforbent  fyftem, 
originates  from  a  fimilar  caufe,  that  of  their  abforptive  powers. 
^  IV.  As  all  the  fluids,  that  pafs  through  thefe  glands,  and  ca- 
pillary veflels,  undergo  a  chemical  change,  acquiring  new  com- 
binations, the  matter  of  heat  is  at  the  fame  time  given  out  ;  this 
is  apparent,  fmce  whatever  increafes  infenfible  perfpiration,  in- 
creafes  the  heat  of  the  ikin  ;  and  when  the  a&ion  of  thefe  veflels 
is  much  increafed  but  for  a  moment,  as  in  bluftiing,  a  vivid  heat 
on  the  fkin  is  the  immediate  confequence.  So  when  great  bil- 
ious fecretions,  or  thofe  of  any  other  gland,  are  produced,  heat 
is  generated  in  the  part  in  proportion  to  the  quantity  of  the  fe- 
cretion. 

The  heat  produced  on  the  fkin  by  blufhing  may  be  thought 
by  fome  too  fudden  to  be  pronounced  a  chemical  effect,  as  the 
fermentations  or  new  combinations  taking  place  in  a  fluid  is  in 
general  a  flower  procefs.  Yet  are  there  many  chemical  mixtures 
in  which  heat  is  given  out  as  inftantaneoufly ;  as  in  foJutions  of 
metals  in  acids,  or  in  mixtures  of  eflential  oils  and  acids,  as  of 
oil  of  cloves  and  acid  of  nitre.  So  the  bruifed  parts  of  an  un- 
ripe apple  become  almoft  inftantaneoufly  fweet ;  and  if  the  chem- 
ico-animal  procefs  of  digeftion  be  flopped  for  but  a  moment,  as 

VOL.  T,  D  D  bv 


2io  CIRCULATORY         SECT.  XXIII.  5. 

by  fear,  or  even  by  voluntary  eructation,  a  great  quantity  of  air 
is  generated,  by  the  fermentation,  which  inftantly  fucceeds  the 
flop  of  digeftion.  By  the  experiments  of  Dr.  Hales  it  appears, 
that  an  apple  during  fermentation  gave  up  above  fix  hundred 
times  its  bulk  of  air  ;  and  the  materials  in  the  .  ftomach  are  fuch 
and  in  fuch  fituation,  as  immediately  to  run  into  fermentation, 
when  digeftion  is  impeded. 

As  the  blood  paiTes  through  the  fmall  veflels  of  the  lungs, 
which  connect  the  pulmonary  artery  and  vein,  it  undergoes  a 
change  of  colour  from  a  dark  to  a  light  red  ;  which  may  be  term- 
ed a  chemical  change,  as  it  is  known  to  be  effeiled  by  an  ad- 
mixture of  oxygene,  or  vital  air  ;  which  according  to  a  difcov- 
ery  ofDr  Prieftley,  pafTes  through  the  mg.i(l  membranes,  which 
conftitute  the  fides  of  thefe  veflels.  As  the  blood  pafles  through 
the  capillary  veflels,  and  glands,  which  connect  the  aorta  and 
its  various  branches  with  their  correfpondent  veins  in  the  ex- 
tremities of  the  body,  it  again  lofes  the  bright  red  colour,  and 
undergoes  fome  new  combinations  in  the  glands  or  capillaries, 
in  which  the  matter  of  heat  is  given  out  from  the  fecreted  fluids. 
This  procefs  therefore,  as  well  as  the  procefs  of  refpiration,  has 
fome  analogy  to  combuftion,  as  the  vital  air  or  oxygene  feems 
to  become  united  to  fome  inflammable  bafe,  and  the  matter 
of  heat  efcapes  from  the  new  acid,  which  is  thus  produced. 

V.  After  the  blood  has  pafled  thefe  glands  and  capillaries, 
and  parted  with  whatever  they  chofe  to  take  from  it,  the  re- 
mainder is  received  by  the  veins  which  are  a  fet  of  blood-abforb- 
ing  veflels  in  general  correfponding  with  the  ramifications  of  the 
arterial  fyftem.  At  the  extremity  of  the  fine  convolutions  of  the 
glands  the  arterial  force  ceafes  ;  this  in  refpedl  to  the  capillary 
veflels,  which  unite  the  extremities  of  the  arteries  with  the  com- 
mencement of  the  veins,  is  evident  to  the  eye,  on  viewing  the 
tail  of  a  tadpole  by  means  of  a  folar,  or  even  by  a  common  mi- 
crofcope,  for  globules  of  blood  are  feen  to  endeavour  to  pafs,  and 
to  return  again  and  again,  before  they  become  abforbed  by  the 
mouths  of  the  veins-,  which  returning  of  thefe  globules  evinces, 
that  the  arterial  force  behind  them  has  ceafed.  The  veins  are 
furnifhed  with  valves  like  the  lymphatic  abforbents  ;  and  the 
great  trunks  of  the  veins,  and  of  the  lacleals  and  lymphatics, 
join  together  before  the  ingrefs  of  their  fluids  into  the  left  cham- 
ber of  the  heart  •,  both  which  evince,  that  the  blood  in  the  veins, 
and  the  lymph  and  chyle  in  the  lacleals  and  lymphatics,  are  car- 
ried on  by  a  fimilar  force ;  otherwife  the  dream,  which  was  pro- 
pelled with  a  lefs  power,  could  not  enter  the  veflels,  which  con- 
tained the  ftream  propelled  with  a  greater  power.  From  whence 
it  appears,  that  the  veins  are  a  fyftem  of  veflels  abforbing  blood, 

as 


SECT.  XXIIL  "<5.  SYSTEM.  2 1 1 

as  the  lafteals  and  lymphatics  are  a  fyftem  of  veflels  abforbing 
chyle  and  Jymph.  See  Sea.  XXVII.  i. 

VI.  The  movements  of  their  adapted  fluids  in  the  various 
veflels  of  the  body  are  carried  forwards  by  the  actions  of  thofe 
veflels  in  confequence  of  two  kinds  of  flimulus,  one  of  which  may 
be  compared  to  a  pleafurable  fenfation  or  defire  inducing  the  vef- 
fel  to  ieize,  and,  as  it  were,  to  fwallow  the  particles  thus  felecT:- 
ed  from  the  blood  ;  as  is  done  by  the  mouths  of  the  various 
glands,  veins,  and  other  abforbents,  which  may  be  called  glandu- 
lar appetency.  The  other  kind  of  ftimulus  may  be  compared 
to  disagreeable  fenfation,  or  averfion,  as  when  the  heart  has  re- 
ceived the  blood,  and  is  ftimulated  by  it  to  pufh  it  forwards  into 
the  arteries  j  the  fame  again  ftimulates  the  arteries  to  contraft, 
and  carry  forwards  the  bloo.d  to  their  extremities,  the  glands 
and  capillaries.  Thus  the  mefenteric  veins  abforb  the  blood 
from  the  inteftines  by  glandular  appentency  and  carry  it  for- 
ward to  the  vena  portarum  ;  which  acting  as  an  artery  con- 
tracts itfelf  by  difagreeable  ftimulus,  and  pufhes  it  to  its  ramified 
extremities,  the  various  glands,  which  conftitute  the  liver. 

It  feems  probable  thar  at  the  begining  of  the  formation  of 
thefc  veflels  in  the  embryon,  an  agreeable  fenfation  was  in  real- 
ity felt  by  the  glanJs  during  fecretion,  as  is  now  felt  in  the  act 
of  fwallowing  palatable  food  ;  and  that  a  difagreeable  fenfation 
was  originally  felt  by  the  heart  from  the  detention  occafioned 
by  the  blood,  or  by  its  chemical  ftimulus  ;  but  that  by  habit 
thefe  are  all  become  irritative  motions  ;  that  is,  fuch  motions 
as  do  not  affect  the  whole  fyitem,  except  when  the  veflels  are 
difeafed  by  inflammation. 


SECT 


212  OF  THE  SALIVA          SECT.  XXIV.  i. 


\  SECT-       XXIV. 

OF   THE   SECRETION   OF   SALIVA,   AND   OF   TEARS,   AND   OF   THE 
LACRYMAL     SACK. 

I.  Secretion  of  faliva  increafed  by  mercury  in  the  blood,  i.  By  the 
food  in  the  mouth.  Drynefs  of  the  mouth  not  from  a  deficiency  of 
faliva.  2.  By  fenfitive  ideas.  3.  By  volition.  4.  By  diftafte- 
ful  fubftances .  It  isfecreted  in  a  dilute  and  f aline  Jlate.  It  then 
becomes  msre  vifcid.  5.  By  ideas  of  diftafteful  fubftances.  6. 
By  naufea.  7.  By  aver/ton.  8.  By  catenation  nvith /Simulating 
Jlubftances  in  the  ear.  II.  I .  Secretion  of  tears  lefs  in  Jleep. 
From  J^imulation  of  their  excretory  duel.  2.  Lacrymal  fack  is  a 
gland.  3.  Its  ufes.  4.  Tears  are  fecreted %  when  the  nafal  duel 
is  jlimulated.  5.  Or  <w hen  it  is  excited  by  fenfation.  6.  Or  by 
volition.  7.  The  lacrymal  fack  can  regurgitate  its  contents  into 
the  eye.  8.  More  tears  are  fecreted  by  ajjbciation  'with  the  irri- 
tation of  the  nafal  duel  of  the  lacrymal  fack ,  than  the  puncla  lacry- 
malia  can  imbibe.  Of  the  gout  in  the  liver  andjlomach. 

I.  THE  falival  glands  drink  up  a  certain  fluid  from  the  cir- 
cumfluent blood,  and  pour  it  into  the  mouth.  They  are  fome- 
times  ftimulated  into  aftion  by  the  blood,  that  furrounds  their 
origin,  or  by  fome  part  of  that  heterogeneous  fluid  :  for  when 
mercurial  falts,  or  oxydes,  are  mixed  with  the  blood,  the  ftim- 
ulate  thefe  glands  into  unnatural  exertions  j  and  then  an  unufual 
quantity  of  faliva  is  feparated. 

1.  As  the  faliva  fecreted  by  thefe  glands  is  mod  wanted  during 
the  maftication  of  our  food,  it  happens,  when  the  terminations 
of  their  dudls  in  the  mouth  are  ftimulated  into  aftion,  the   fali- 
val glands  themfelves  are  brought  into  increafed  a£Hon  at  the 
fame  time  by  aflbciation,  and  feparate  a  greater  quantity  of  their 
juices  from  the  blood  j    in  the  fame  manner  as  tears  are  produ- 
ced in  greater  abundance  during  the  ftimulus  of  the  vapour  of 
onions,  or  of  any  other  acrid  material  in  the  eye. 

The  faliva  is  thus  naturally  poured  into  the  mouth  only  du- 
ring the  ftimulus  of  our  food  in  maftication  ;  for  when  there  is 
too  great  an  exhalation  of  the  mucilaginous  fecretion  from  the 
membranes,  which  line  the  mouth,  or  too  great  an  abforption  of 
it,  the  mouth  becomes  dry,  though  there  is  no  deficiency  in  the 
quantity  of  faliva  ;  as  in  thofe  who  fleep  with  their  mouths 
open,  and  in  fome  fevers. 

2.  Though  during  the  maftication  of  our  natural  food  the  fa- 
lival glands  are  excited  into  aftion  by  the  ftimulus  on  their  ex- 
cretory 


SECT.  XXIV.  j.  3.         AND  TEARS.  213 

cretory  dufts,  and  a  due  quantity  of  faliva  is  feparated  from  the 
blood,  and  poured  into  the  mouth  ;  yet  as  this  maftication  of  our 
food  is  always  attended  with  a  degree  of  pleafure ;  and  that 
pleafurable  fenfation  is  alfo  connected  with  our  ideas  of  certain 
kinds  of  aliment ;  it  follows,  that  when  thefe  ideas  are  repro- 
duced, the  pleafurable  fenfation  arifes  along  with  them,  and  the 
falival  glands  are  excited  into  adion,  and  fill  the  mouth  with  fa- 
liva from  this  fenfitive  aflbciation,  as  is  frequently  feen  in  dogs, 
who  flaver  at  the  fight  of  food. 

3.  We  have  alfo  a  voluntary  power  over  the  a£Uon  of   thefe 
falival  glands,  for  we  can  at  any  time  produce  a  flow  of  faliva 
into  our  mouth,  and  fpit  out,  or  fwallow  it  at  will. 

4.  If  any  very  acid  material  be  held  in  the  mouth,  as  the 
root  of  pyrethrum,  or  the  leaves  of  tobacco,  the  falival  glands  are 
ftimulated  into  flronger  action  than  is  natural,  and  thence  fe- 
crete  a  much  larger  quantity  of  faliva  ;  which  is  at  the  fame 
time  more  vifcid  than  in  its  natural  Rate  ;  becaufe  the  lymphat- 
ics, that  open  their  mouths  into  the  dufts  of  the  falival  glands, 
and  on  the  membranes,  which  line  the  mouth,  are  likewife  ftim- 
ulated into  ftronger  adlion,  and  abforb  the  more  liquid  parts  of 
the  faliva  with  greater  avidity  ;  and  the  remainder  is  left  both  in 
greater  quantity  and  more  vifcid. 

The  increafed  abforption  in  the  mouth  by  fome  ftimulanng 
fubftances,  which  are  called  aftringents,  as  crab-juice,  is  evident 
from  the  inftant  drynefs  produced  in  the  mouth  by  a  fmall 
quantity  of  them. 

As  the  extremities  of  the  glands  are  of  exquifite  tenuity,  as 
appears  by  their  difficulty  of  injedlion,  it  was  neceflary  foi  them 
to  fecrete  their  fluids  in  a  very  dilute  (late  ;  and,  probably  lor  the 
purpofe  of  ftimulating  them  into  adion,  a  quantity  of  neutral 
fait  is  likewife  fecreted  or  formed  by  the  gland.  This  aqueous 
and  faline  part  of  all  fecreted  fluids  is  again  reabforbed  into  the 
habit.  More  than  half  of  fome  fecreted  fluids  is  thus  imbibed 
from  the  refervoirs,  into  which  they  are  poured  ;  as  in  the  urin- 
ary bladder  much  more  than  half  of  what  is  fecreted  by  the  kid- 
neys becomes  reabforbed  by  the  lymphatics,  which  are  thickly 
difperfed  around  the  neck  of  the  bladder.  This  feems  to  be  the 
purpofe  of  the  urinary  bladders  of  fifh,  as  otherwife  fuch  a  re- 
ceptacle for  the  urine  could  have  been  of  no  ufe  to  an  animal 
immerfed  in  water. 

5.  The  idea  of  fubftances  difagreeably  acrid  will  alfo  produce 
a  quantity  of  faliva  in  the  mouth ;  as  when  we  fmell  very  putrid 
vapours,  we  are  induced  to  fpit  out  our  faliva,  as  if  fomething 
difagreeable  was  a&ually  upon  our  palates. 

6.  When  difagreeable  food  in  the  ftomach  produces  naufea, 

a  flow 


2i4  OF  THE  SALIVA       SECT.  XXIV.  i.  7. 

a  flow  of  faliva  is  excited  in  the  mouth  by  aflbciation  ;  as  efforts 
to  vomit  are  frequently  produced  by  difagreeable  drugs  in  the 
mouth  by  the  fame  kind  of  afTociation. 

7.  A  preternatural  flow  of  faliva  is  likewife  fometimes  occa- 
fioned  by  a  difeafe  of  the  voluntary  power  ;  for  if  we  think  about 
our  faliva,  and  determine  not  to  fwallow  it,  or  not  to  fpit  it  out, 
an  exertion  is  produced  by  the  will,  and  more  faliva  is  fecreted 
againft  our  wi(h  ;  that  is,  by  our  averfion,  which  bears  the  fame 
analogy  to  defire,    as   pain  does  to  pleafure  ;  as  they  are  only 
modifications    of  the    fame  difpofition  of  the  fenforium.     See 
ClafsIV.  3.  2.  i. 

8.  The  quantity  of  faliva  may  alfo  be  increafed  beyond  what 
is  natural,  by  the  catenation  of  the  motions  of  thefe  glands  with 
other  motions,   or   fenfations,  as  by  an  extraneous  body  in  the 
ear  ;  of  which  I  have  known  an  inftance  ;   or  by  the  application 
of  ftizolobium,  filiqua  hirfuta,  cowhage,  to  the  feat  of  the  paro- 
tis,  as  ibmc  writers  have  affirmed. 

II.  i.  The  lacrymal  gland  drinks  up  a  certain  fluid  from  the 
circumfluent  blood,  and  pours  it  on  the  ball  of  the  eye,  on  the 
upper  part  of  the  external  corner  of  the  eyelids.  Though  it  may 
perhaps  be  ftimulated  into  the  performance  of  its  natural  action 
by  the  blood,  which  furrounds  its  origin,  or  by  fome  part  of  that 
heterogeneous  fluid  ;  yet  as  the  tears  fecreted  by  this  gland  are 
more  wanted  at  fome  times  than  at  others,  its  fecretion  is  varia- 
ble, like  that  of  the  faliva  above  mentioned,  and  is  chiefly  pro- 
duced when  its  excretory  du6l  is  ftimulated  ;  for  in  our  common 
fleep  there  feems  to  be  little  or  no  fecretion  of  tears •,  though 
they  are  occafionally  produced  by  our  fenfations  in  dreams. 

Thus  when  any  extraneous  material  on  the  eye-ball,  or  the 
drynefs  of  the  external  covering  of  it,  or  the  coldnefs  of  the  air, 
or  the  acrimony  of  fome  vapours,  as  of  onions,  flimulates  the 
excretory  duct  of  the  lacrymal  gland,  it  difcharges  its  contents 
upon  the  ball ;  a  quicker  fecretion  takes  place  in  the  gland,  and 
abundant  tears  fucceed,  to  moiften,  clean,  and  lubricate  the  eye, 

Thefe  by  frequent  nictitation  are  diffufed  over  the  whole  ball, 
and  as  the  external  angle  of  the  eye  in  winking  is  clofed  fooner 
than  the  internal  angle,  the  tears  are  gradually  driven  forwards, 
and  downwards  from  the  lacrymal  gland  to  the  punclalacryma- 
lia. 

2.  The  lacrymal  feck,  with  its  punfta  lacrymalia,  and  its  nafal 
duel,  is  a  complete  gland  ;  and  is  (angular  in  this  refpecl,  that  it 
neither  derives  its  fluid  from,  nor  difgorges  it  into  the  circulation. 
The  fimplicity  of  the  ftrufture  of  this  gland,  and  both  the  ex- 
tremities of  it  being  on  the  furface  of  the  body,  makes  it  well 
worthy  our  minuter  obfervation;  as  the  actions  of  more  intricate 

and 


SECT.  XXIV.  2. 3.          AND  TEARS.  215 

and  concealed  glands  may  be  better  underftood  from  their  anal- 
ogy to  this. 

3.  This  (imple  gland  confifts  of  two  abforbing  mouths,  a  bel- 
ly, and  an  excretory  duct.     As  the  tears  are  brought  to  the  in- 
ternal angle  of  the  eye,  thofe  two  mouths  drink  them  up,  being 
itimulated  into  a£hon  by  this  fluid,   which  they  abiorb.     The 
belly  of  the  gland,  or  lacrymal  fack,  is  thus  filled,  in  which  the 
faline  part  of  the  tears  is  abforbed,  and  when  the  other  end  of 
the  gland  or  nafal  dud,  is  ftimulated  by  the  drynefs,  or  pained 
by  the  coldnefs  of  the  air,  or  affecled  by  any  acrimonious  dull 
or  vapour  in  the  noftrils,  it  is  excited  into  a£lion  together  with 
the  fack,  and  the  tears  are  difgorged  upon  the  membrane,  which 
lines  the  noftrils  \  where  they  ferve  a  fecond  purpofe  to  moiften, 
clean,  and  lubricate,  the  organ  of  fmell. 

4.  This  giand,  when  its  nafal,  du6l,  is  ftimulated  by  any  very 
acrid  material,  as  the  powder  of  tobacco,  or  volatile  fpirits,  not  on- 
ly difgorges  the  contents  of  its  belly  or  receptacle  (the  lacrymal 
fack),  and  abforbs  haftily  all  the  fluid,  that  is  ready  for  it  in  the 
corner  of  the  eye  ;   but  by  the  aflbciation  of  its  motions  with 
thofe  of  the  lacrymal  gland,  excites  that  alfo  into  increafed  ac- 
tion, and  a  large  flow  of  tears  is  poured  into  the  eye. 

5.  This  nafal  duft   is  like  wife  excited  into  ftrong  action  by 
fenfitive  ideas,  as  in  grief,  or  joy,  and  then  aifo  by  its  ailbciations 
with  the  lacrymal  gland  it  produces  a  great  flow  of  tears  with- 
out any  external   ftimulus ;  as  is  more  fully  explained  in  Sedl, 
XVI.  8.  on  Inftind. 

6.  There  are  fome,  famous  in  the  arts  of  exciting  compaflion, 
who  are  faid  to  have  acquired  a  voluntary  power  of  producing  a 
flow  of  tears  in  the  eye  ;  which  from  what  has  been  faid  in  the 
fection  on  Inftindl  above  mentioned,  I  ftiould  fufpedt,  is  perfom- 
ed  by  acquiring  a  voluntary  power  over  the  adtion  of  this  nafal 
duct. 

7.  There  is  another  circumftance  well  worthy  our  attention, 
that  when  by  any  accident  this  nafal  dudl  is  obftru&ed,  the  lac- 
rymal fack,   which  is  the  belly  or  receptacle  of  this  gland,  by 
flight  prdlure  of  the  finger  is  enabled  to  difgorge  its  contents 
again  into  the  eye  ;  perhaps  the  bile  in  the  fame  manner,  when 
the  biliary  duds  are  obftrudted,  is  returned  into  the  blood  by 
veflels  which  fecrete  it  ? 

8.  A  very  important  though  minute  occurrence  muft  here  be 
obferved,  that  though  the  lacrymal  gland  is  only  excited  into  ac- 
tion, when  we  weep  at  a  diftrefsful  tale,  by  its  affociation  with 
this  naial  duct,  as  is  more  fully  explained  in  Sett.  XVI.  8  ,  yet  the 
quantity  of  tears  fecreted  at  once  is  more  than  the  puncla  lacry- 
malia  can  readily  abiorb  5  which  {hews  that  the  motions  occafwned 

h 


2i6  OF  THE  SALIVA,  &c.    SECT.  XXIV.  2.  8. 

by  ajficiations  are  frequently  more  energetic  than  the  original  motions^ 
by  which  they  were  occaftoned.  Which  we  fhall  have  occafion  to 
mention  hereafter,  to  illuftrate,  why  pains  frequently  exift  in  a 
part  diftant  from  the  caufe  of  them,  as  in  the  other  end  of  the 
urethra,  when  a  (tone  ftimulates  the  neck  of  the  bladder.  And 
why  inflamations  frequently  arife  in  parts  diftant  from  their 
caufe,  as  the  gutta  rofea  of  drinking  people,  from  an  inflamed 
liver. 

The  inflammation  of  a  part  is  generally  preceded  by  a  torpor 
or  quiefcence  of  it ;  if  this  exifts  in  any  larger  congeries  of  glands, 
as  in  the  liver,  or  any  membranous  part,  as  the  ftomach,  pain 
is  produced  and  chillinefs  in  confequence  of  the  torpor  of  the 
vefiels.  In  this  fituation  fometimes  an  inflammation  of  the  parts 
fucceeds  the  torpor ;  at  other  times  a  diftant  more  fenfible  part  be- 
comes inflamed  ;  whofe  actions  have  previoufly  been  affbciated 
with  it :  and  the  torpor  of  the  firft  part  ceafes.  This  I  appre- 
hend happens,  when  the  gout  of  the  foot  fucceeds  a  pain  of  the 
biliary  duel:,  or  of  the  ftomach.  Laftly,  it  fometimes  happens, 
that  the  pain  of  torpor  exifts  without  any  confequent  inflamma- 
tion of  the  affected  part,  or  of  any  diftant  part  aflbciated  with  it, 
as  in  the  membranes  about  the  temple  and  eye-brows  in  hemi- 
crania,  and  in  thofe  pains  which  occafion  convulfions  \  if  this 
happens  to  gouty  people,  when  it  affects  the  liver,  I  fuppofe  epi- 
leptic fits  are  produced ;  and,  when  it  affects  the  ftomach,  death 
is  the  confequence.  In  thefe  cafes  the  pulfe  is  weak,  and  the 
extremities  cold,  and  fuch  medicines  as  ftimulate  the  quiefcent 
parts  into  action,  or  which  induce  inflammation  in  them,  or  in 
any  diftant  part,  which  is  aflbciated  with  them,  cures  the  pref- 
cnt  pain  of  torpor,  and  faves  the  patient. 

I  have  twice  feen  a  gouty  inflammation  of  the  liver,  attended 
with  jaundice  ;  the  patients  after  a  few  days  were  both  of  them 
affected  with  cold  fits,  like  ague  fits,  and  their  feet  became  af- 
fected with  gout,  and  the  inflammation  of  their  livers  ceafed. 
It  is  probable,  that  the  uneafy  fenfations  about  the  ftomach,  and 
indigeftion,  which  precedes  gouty  paroxyfms,  are  generally  ow- 
ing to  torpor  or  flight  inflammation  of  the  liver,  and  biliary 
ducts  ;  but  where  great  pain  with  continued  ficknefs,  with  feeble 
pulfe,  and  fenfation  of  cold,  affect  the  ftomach  in  patients  debil- 
itated by  the  gout,  that  it  is  a  torpor  of  the  ftomach  itfelf,  and 
deftroys  the  patient  from  the  great  connexion  of  that  vifcus  with 
the  vital  organs.  See  Sect.  XXV.  17. 


SECT. 


SECT.  XXV.  i,       OF  THE  STOMACH,  &c.  217 

SECT-      XXV. 

OF    THE    STOMACH    AND    INTESTINES. 

(.  Of  f wallowing  our  food.  Ruminating  animals.  2.  Aclion  of 
thejlomach  3.  Aftion  of  the  inteftines.  irritative  motions  con- 
necled  with  thefe.  4.  Effects  of  repletion.  5.  Stronger  aclion 
of  the  ftomach  and  inteftines  from  more  ftimulating  food.  6. 
Their  aclion  inverted  by  ftill  greater  ftimuli.  Or  by  difguflful 
ideas.  Or  by  volition.  7.  Other  glands  ftrengthen  or  invert 
their  motions  by  fympathy.  8.  Vomiting  performed  by  intervals. 
9.  Inverjion  of  the  cutaneous  abforbents.  10.  Increafed  fecretion 
of  bile  and  pancreatic  juice.  II.  Inverfton  of  the  lacleals.  12. 
And  of  the  bile-duels.  1 3 .  Cafe  of  a  cholera.  1 4  Farther  ac- 
count of  the  invtrfion  of  lacJeal.  I J ,  Iliac  pajfion.  Valve  of 
the  colon.  16.  Cure  of  the  iliac  pajffion.  17  Pain  of  gall- 
ft  one  diftinguijhed  from  pain  of  the  ftomach.  Gout  of  the  ftomacb 
from  torpor •,  from  inflammation.  Intermitting  pulfe  owing  to  in- 
digejlion.  To  overdofe  of  foxglove.  Weak  pulfe  from  emetics. 
Death  from  a  blow  on  thejlomach.  From  gout  of 'the  Jiomach. 

1.  THE  throat,  ftomach,  and  inteftines,  may  be  confidered  as 
one  great  gland  ;  which  like  the  lachrymal  fack  above  mentioned, 
neither  begins  nor  ends  in  the  circulation.     Though  the  adl  of 
mafticating  our  aliment  belongs  to  the  fenfitive  clafs  of  motions, 
for  the  pleafure  of  its  tafte  induces  the  mufcles  of  the  jaw  into 
a6Uon  ;  yet  the  deglutition  of  it  when  mafticated  is  generally, 
if  not  always,  an  irritative  motion,  occafioned  by  the  application 
of  the  food  already  mafticated  to  the  origin  of  the  pharinx  ;  in 
the  fame  manner  as  we  often  fwallow  our  fpittle  without  attendi- 
ing  to  it. 

The  ruminating  clafs  of  animals  have  the  power  to  invert  the 
motion  of  their  gullet,  and  of  their  firft  ftomach,  from  the  ftim- 
ulus  of  this  aliment,  when  it  is  a  little  further  prepared  ;  as  is 
their  daily  practice  in  chewing  the  cud  :  and  appears  to  the  eye 
of  any  one,  who  attends  to  them,  whilft  they  are  employed  iu 
this  fecond  maftication  of  their  food. 

2.  When  our  natural  aliment  arrives  into  the  ftomach,  this  or- 
gan is  ftimulated  into  its  proper  vermicular  action ;    which  be- 
ginning at  the  upper  orifice  of  it,  and  terminating  at  the  lower 
one,  gradually  mixes  together  and  pufhes  forwards  the  digefting 
materials  into  the  inteftine  beneath  it. 

At  the  fame  time  the  glands,  that  fupply  the  gaftric  juices, 
which  are  neceflary  to  promote  the  chemical  part  of  the  procefs 
VOL,  I.  E  E  '    of 


ai8  OF  THE  STOMACH          SECT.  XXV.  3. 

of  digeftion,  are  ftimulated  to  difcharge  their  continued  fluids, 
and  to  feparate  a  further  fupply  from  the  blood-veflels :  and  the 
la&eals  or  lymphatics,  which  open  their  mouths  into  the  ftomach, 
are  Simulated  into  action,  and  take  up  fome  part  of  the  digefting 
materials. 

3.  The  remainder  of  thefe  digefting  materials  is  carried  for- 
wards into  the  upper  inteftines,  and  ftimulates  them  into  their 
periftaltic  motion  tlmilar  to  that  of  the  ftomach  \  which  contin- 
ues gradually  to  mix  the  changing  materials,  and  pafs  them  along 
through  the  valve  of  the  colon  to  the  excretory  end  of  this  great 
gland,  the  fphincter  ani. 

The  digefting  materials  produce  a  flow  of  bile,  and  of  pancre- 
atic juice,  as  they  pafs  along  the  duodenum,  by  ftimulating  the 
excrerory  du<5ls  of  the  liver  and  pancreas,  which  terminate  in 
that  inteftine  :  and  other  branches  of  the  abforbent  or  lymphatic 
fyitem,  called  lacleals,  are  excited  to  drink  up,  as  it  pafles,  thofe 
parts  of  the  digefting  materials,  that  are  proper  for  iheir  purpofe, 
by  its  ftimulus  on  their  mouths. 

4.  When  the  ftomach  and  inteftines  are  thus  filled  with  their 
proper  food,  not  only  the  motions  of  the  gaftric  glands,  the  pan- 
creas, liver,  and  lafteal  vefTels,  are  excited  into  action  ;    but  at 
the  fame  time  the  whole  tribe  of  irritative  motions  are  exerted 
with  greater  energy,  a  greater  degree  of  warmth,  colour,  plump- 
nefs,  and  moifture,  is  given  to  the  {kin  from  the  increafed  adlion 
of  thofe  glands  called  capillary  veffels  ;  pleafurable  fenfation  is 
excited,  the  voluntary  motions  are  lefs  eafily  exerted,  and    at 
length  fufpended  ;  and  fleep  fucceeds,  unlefs  it  be  prevented  by 
the  ftimulus  of  iurrounding  objects,  or  by  voluntary  exertion,  or 
by  an  acquired  habit,  which  was  originally  produced  by  one  or 
other  of  thefe  circumftances,   as  is  explained  in  Se6t  XXI.  on 
Drunkennefs. 

At  this  time  alfo,  as  the  blood- veiTels  become  replete  with 
chyle,  more  urine  is  feparated  into  the  bladder,  and  lefs  of  it  is 
reabforbed  ;  more  mucus  poured  into  the  cellular  membranes, 
and  lefs  of  it  reabforbed  :  the  pulfe  becomes  fuller,  and  fofter, 
and  in  general  quicker.  The  reafon  why  lefs  urine  and  cellular 
mucus  is  abforbed  after  a  full  meal  with  fufficient  drink  is  owing 
to  the  blood-veflels  being  fuller  :  hence  one  means  to  promote  ab- 
forption  is  to  decreafe  the  refiftance  by  emptying  the  vefTels  by 
venefedlion.  From  this  decreafed  abforption,  the  urine  becomes 
pale  as  well  as  copious,  and  the  (kin  appears  plump  as  well  as 
florid. 

By  daily  repetition  of  thefe  movements  they  all  become  con- 
nedted  together,  and  make  a  diurnal  circle  of  irritative  ad  ion, 

and 


SECT.  XXV.  5.        AND  INTESTINES.  -219 

and  if  one  of  this  chain  be  difturbed,  the  whole  is  liable  to  be 
put  into  diforder.     See  Sect.  XX.  on  Vertigo. 

5.  When  the  ftomach  and  inteflines  receive  a  quantity  of  food, 
whofe  ftimulus  is  greater  than  ufual,  all  their  motions,  and  thofe 
of  the  glands  and  lymphatics,  are  ftimuhted  into  (Ironger  aclion 
than  ufual,  and  perform  their  offices  with  greater  vigour  and  in 
lefs  time  :  fuch  are  the  effects  of  certain  quantities  of  fpice  or  of 
vinous  fpirit. 

6.  But  if  the  quantity  or  duration   of  thefe  ftimuli  are  ftili 
further  increafed,  the  ftomach  and  throat  are  ftimulated  into  a 
motidt*.  whofe  direction  is  contrary  to  the  natural  one  above  de- 
fcribed  ;  and  they  regurgitate  the  materials,  which  they  contain, 
inftead  of  carrying  them  forwards.  This  retrograde  motion  of  the 
ftomach  may  be  compared  to  the  itretchings  of  wearied  limbs  the 
contrary  way,  and  is  well  elucidated  by  the  following  experiment. 
Look  earneflly  for  a  minute  or  two  on  an  area  an  inch  fquare  of 
pink  filk,  placed  in  a  ftrong  light,  the  eye  becomes  fatigued,  the 
colour  becomes  faint,   and  at  length  vanifhes,   for  the  fatigued 
eye  can  no  longer  be  ftimulated  into  direct  motions ;  then  on 
clofing  the  eye  a  green  fpedrum  will  appear  in  if,    which  is  a 
colour  direftly  contrary  to  pink,  and  which  will  appear  and  dif- 
appear  repeatedly,  like   the   efforts   in  vomiting.     See  Seclion. 
XXIX.  ii. 

Hence  all  thofe  drugs,  which  by  their  bitter  or  aftringent  ftim- 
ulus increafe  the  action  of  the  ftomach,  as  camomile  and  white 
vitriol,  if  their  quantity  is  increafed  above  a  certain  dofe  become 
emetics. 

Thefe  inverted  motions  of  the  ftomach  and  throat  are  gener- 
ally produced  from  the  ftimulusof  unnatural  food,  and  are  attend- 
ed with  the  fenfation  of  naufea  or  ficknefs  :  but  as  this  fenfation 
is  again  connected  with  an  idea  of  the  diftafteful  food,  which 
induced  it ;  fo  an  idea  of  naufeous  food  will  alfo  fometimes  ex- 
cite the  action  of  naufea  ;  and  that  give  rife  by  aflbciation  to  the 
inverfion  of  the  motions  of  the  ftomach  and  throat.  As  fome, 
who  have  .had  horfe-flefh  or  dogs-flefh  given  them  for  beef  or 
mutton,  are  faid  to  have  vomited  many  hours  afterwards,  when 
thev  have  been  told  of  the  impofition. 

I  have  been  told  of  a  perfon,  who  had  gained  a  voluntary  com- 
mand over  thefe  inverted  motions  of  the  (tomach  and  throat,  and 
Supported  himfelf  by  exhibiting  this  cufiofity  to  the  public.  At 
thefe  exhibitions  he  fwallowed  a  pint  of  red  rough  goofeberries, 
and  a  pint  of  white  fmooth  ones,  brought  them  up  in  fmall  par- 
cels into  his  mouth,  and  reftored  them  feparately  to  the  fpecta- 
tors,  who  called  for  red  or  white  as  they  pleafed,  till  the  whole 
were  redelivered. 

7.  At 


220  OF  T&£  STOMACH          SECT.  XXV.  7. 

7.  At  the  fame  time  that  thefe  motions  ol  the  ftomach  and 
throat  are  ftimulated  into  inverfion,  fome  of  the  other  irritative 
motions  that  had  acquired  more  immediate  connexions  with  the 
ftomach,  as  thofe  of  the  gaftric  glands,  are  excited  into  ftronger 
aftion  by  this  affociation  ;   and  fome  other  of  thefe   motions, 
which  are  more  eafily  excited,  as  thofe  of  the  gaftric  lymphatics, 
are  inverted  by  their  aflbciation  with  the  retrograde  motions  of 
the  ftomach,  and  regurgitate  their  contents,   and  thus  a  greater 
quantity  of  mucus,  and  of  lymph,  or  chyle,  is  poured  into  the 
ftomach,  and  thrown  up  along  with  its  contents. 

8.  Thefe  inverfions  of  the  motion  of  the  ftomach  in  vomiting 
are  performed  by  intervals,  for  the  fame  reafon  that  many  otner 
motions  are  reciprocally  exerted  and  relaxed  ;  for   during  the 
time  of  exertion  the  ftimulus,  or  fenfation,  which  caufed  this  ex- 
ertion is  not  perceived  ;  but  begins  to  be  perceived  again,  as 
foon  as  the  exertion  ceafes,  and  is  fome  time  in  again  producing 
its  effect.     As  explained  in  Sect.  XXXIV.  on  Volition,  where 
it  is  thewn,  that  the  contractions  of  the  fibres,  and  the  fenfation 
of  pain,  which  occafioned  that  exertion,  cannot  exift  at  the  fame 
time.     The  exertion  ceafes  from  another  caufe  aifo,  which  is  the 
exhauftion  of  the  fenforial  power  of  the  part  and  thefe  two  cauf- 
es  frequently  operate  together. 

9.  At  the  times  of  thefe  inverted  efforts  of  the  ftomach  not  on- 
ly the  lymphatics,  which  open  their  mouths  into  the  ftomach, 
but  thofe  of  the  ikin  alfo,  are  for  a  time  inverted  :  for  iweats  are 
fometimes  pufhed  out  during  the  efforts  of  vomiting  without  an 
increafe  of  h6at. 

10.  But  if  by  a  greater  ftimulus  the  motions  of  the  ftomach 
are  inverted  ftill  more  violently  or  more  permanently,  the  duod- 
enum has  its  periftaltic    motions  inverted  at  the  lame  time  by 
their  affociation  with  thofe  of  the  ftomach  ;  and  the  bile  and  pan- 
creatic juice,  which  it  contains,  are  by  the  inverted  motions 
brought  up  into  the  ftomach,  and  difcharged  along  with  its  eon^ 
tents ;  while  a  great  quantity  of  bile  and  pancreatic  juice  is  pour- 
ed into  this  inteftine  ;  as  the  glands  that  fecrete  them,  are  by 
their  affociation  with  the  motions  of  the  inteftine  excited  into 
ftronger  acUon  than  ufual. 

11.  The  other  inteftines  are  by  affociation  excited  into  more; 
powerful  action,  while  the  lymphatics,  that  open  their  mouths 
into  them  fuffer  an  inverfion  of  their  motions  correfponding  with 
the  lymphatics  of  the  ftomach  and  duodenum  ;  which  with  a 
part  of  the  abundant  fecretion  of  bile  is  carried  downwards,  and 
contributes  both  to  ftimulate  the  bowels,  and  to  increafe  the  quan- 
tity of  the  evacuations.    This  inverfion  of  the  motion  of  the  lym- 
phatic* appears  from  the  quantity  of  chyle,  which  comes  away 


SECT.  XXV.  12.      AND  INTESTINES.  221 

by  ftools  ;  which  is  otherwife  abforbed  as  foon  as  produced, 
and  by  the  immenfe  quantity  of  thin  fluid,  which  is  evacuated 
along  with  it. 

1 2.  But  if  the  ftimulus,  which  inverts  the  ftomach,  be  (till 
more  powerful,  or  more  permanent,  it  fometimes  happens,  that 
the  motions  of  the  biliary  glands,  and  of  their  excretory  dudls, 
are  at  the  fame  time  inverted,  and  regurgitate  their  contained 
bile  into  the  blood-veflels,  as  appears  by  the  yellow  colour  of  the 
ikin,  and  of  the  urine  ;  and  it  is  probable  the  pancreatic  fecretion 
may  fuffer  an  inverfion  at  the  fame  time,  though  we  have  yet  no 
mark  by  which  this  can  be  afcertained. 

1 3  Mr.  . ate  two  putrid  pigeons  out  of  a  cold  pigeon- 

pye,  arid  drank  about  a  pint  of  beer  and  ale  along  with  them, 
and  immediately  rode  about  five  miles.  He  was  then  feized 
with  vomiting,  which  was  after  a  few  periods  fucceededby  purg- 
ing ;  theie  continued  alternately  for  two  hours  ;  and  the  purg- 
ing continued  by  intervals  for  fix  or  eight  hours  longer.  Dur- 
ing this  time  he  could  not  force  himfelf  to  drink  more  than  one 
pint  in  the  whole  ;  this  great  inability  to  drink  was  owing  to  the 
naufea,  or  inverted  motions  of  the  ftomach,  which  the  voluntary 
exertion  of  fwallowing  could  feldom  and  with  difficulty  over- 
come; yet  he  difcharged  in  the  whole  at  lead  fix  quarts;  whence 
came  this  quantity  of  liquid  ?  Firft,  the  contents  of  the  ftomach 
were  emitted,  then  of  the  duodenum,  gall-bladder,  and  pancreas, 
by  vomiting.  After  this  the  contents  of  the  lower  bowels  ;  then 
the  chyle,  that  was  in  the  lafteal  veflels,  and  in  the  receptacle 
of  chyle,  was  regurgitated  into  the  inteftines  by  a  retrograde  mo- 
tion of  thefe  veflels.  And  afterwards  the  mucus  depofited  in  the 
cellular  membrane,  and  on  the  furface  of  all  the  other  mem- 
branes, feems  to  have  been  abforbed  ;  and  with  the  fluid  abforb- 
ed from  the  air  to  have  been  carried  by  their  refpeftive  lymphat- 
ic branches  by  the  increafed  energy  of  their  natural  motions, 
and  down  the  vifceral  lymphatics,  of  lafteals,  by  the  inverfion  of 
their  motions. 

14.  It  may  be  difficult  to  invent  experiments  to  demonftrate 
the  truth  of  this  inverfion  of  fome  branches  of  the  abforbent  fyf- 
tem,  and  increafed  abforption  of  others  ;  but  the  analogy  of  thefe 
veflels  to  the  inteftinal  canal,  and  the  fymptoms  of  many  difeaf- 
es,  render  this  opinion  more  probable  than  many  other  received 
opinions  of  the  animal  economy. 

In  the  above  inftance,  after  the  yellow  excrement  was  voided, 
the  fluid  ceafed  to  have  any  frriell,  and  appeared  like  curdled 
milk,  and  then  thinner  fluid,  and  fome  mucus,  were  evacuated  : 
did  not  thefe  feem  to  partake  of  the  chyle,  of  the  mucous  fluid 
from  all  the  cells  of  the  body,  and  laftly,  of  the  atmofpheric  moif- 

ture  ? 


220  OF  T&£  STOMACH          SECT.  XXV.  j. 

7.  At  the  fame  time  that  thefe  motions  of  the  ftomach  and 
throat  are  ftimulated  into  inverfion,  fome  of  the  other  irritative 
motions  that  had  acquired  more  immediate  connexions  with  the 
ftomach,  as  thofe  of  the  gaftric  glands,  are  excited  into  ftronger 
action  by  this  affociation  ;   and  fome  other  of  thefe   motions, 
which  are  more  eafily  excited,  as  thofe  of  the  gaftric  lymphatics, 
are  inverted  by  their  aflbciation  with  the  retrograde  motions  of 
the  ftomach,  and  regurgitate  their  contents,   and  thus  a  greater 
quantity  of  mucus,  and  of  lymph,  or  chyle,  is  poured  into  the 
ftomach,  and  thrown  up  along  with  its  contents. 

8.  Thefe  inverfions  of  the  motion  of  the  ftomach  in  vomiting 
are  performed  by  intervals,  for  the  fame  reafon  that  many  other 
motions  are  reciprocally  exerted  and  relaxed  ;  for   during  the 
time  of  exertion  the  ftimulus,  or  fenfation,  which  caufed  this  ex- 
ertion is   not  perceived  ;  but   begins  to  be  perceived  again,  as 
foon  as  the  exertion  ceafes,  and  is  fome  time  in  again  producing 
its  effect.     As  explained  in  Se£l.  XXXIV.  on  Volition,  where 
it  is  {hewn,  that  the  contractions  of  the  fibres,  and  the  fenfation 
of  pain,  which  occafioned  that  exertion,  cannot  exift  at  the  fame 
time.     The  exertion  ceafes  from  another  caufe  aifo,  which  is  the 
exhauftion  of  the  fenforial  power  of  the  part  and  thefe  two  cauf- 
es  frequently  operate  together* 

9.  At  the  times  of  thefe  inverted  efforts  of  the  ftomach  not  on- 
ly the  lymphatics,  which  open  their  mouths  into  the  ftomach, 
but  thofe  of  the  fkin  alfo,  are  for  a  time  inverted  :  for  Iweats  are 
fometimes  pufhed  out  during  the  efforts  of  vomiting  without  an 
increafe  of  heat. 

TO.  But  if  by  a  greater  ftimulus  the  motions  of  the  ftomach 
are  inverted  ftill  more  violently  or  more  permanently,  the  duod- 
enum has  its  periftaltic  motions  inverted  at  the  lame  time  by 
their  aflbciation  with  thofe  of  the  ftomach  ;  and  the  bile  and  pan- 
creatic juice,  which  it  contains,  are  by  the  inverted  motions 
brought  up  into  the  ftomach,  and  difcharged  along  with  its  eon*, 
tents ;  while  a  great  quantity  of  bile  and  pancreatic  juice  is  pour- 
ed into  this  inteftine  ;  as  the  glands  that  fecrete  them,  are  by 
their  aflbciation  with  the  motions  of  the  inteftine  excited  into 
ftronger  ad  ion  than  ufual. 

ii.  The  other  inteftines  are  by  aflbciation  excited  into  more; 
powerful  action,  while  the  lymphatics,  that  open  their  mouths 
into  them  fuffer  an  inverfion  of  their  motions  correfponding  with 
the  lymphatics  of  the  ftomach  and  duodenum  ;  which  with  a 
part  of  the  abundant  fecretion  of  bile  is  carried  downwards,  and 
contributes  both  to  ftimulate  the  bowels,  and  to  increafe  the  quan- 
tity of  the  evacuations.  This  inverfion  of  the  motion  of  the  lym- 
phatic* appears  from  the  quantity  of  chyle,  which  comes  away 


SECT.  XXV.  12.      AND  INTESTINES.  221 

by  ftools  ;  which  is  otherwife  abforbed  as  foon  as  produced, 
and  by  the  immenfe  quantity  of  thin  fluid,  which  is  evacuated 
along  with  it. 

1 2.  But  if  the  flimulus,  which  inverts  the  ftomach,  be  (till 
more  powerful,  or  more  permanent,  it  fometimes  happens,  that 
the  motions  of  the  biliary  glands,  and  of  their  excretory  duels, 
are  at  the  fame  time  inverted,  and  regurgitate  their  contained 
bile  into  the  blood-veiTels,  as  appears  by  the  yellow  colour  of  the 
ikin,  and  of  the  urine  ;  and  it  is  probable  the  pancreatic  fecretion 
may  fuffer  an  inverfion  at  the  fame  time,  though  we  have  yet  no 
mark  by  which  this  can  be  afcertained. 

1 3  Mr.  . ate  two  putrid  pigeons  out  of  a  cold  pigeon- 

pye,  and  drank  about  a  pint  of  beer  and  ale  along  with  them, 
and  immediately  rode  about  five  miles.  He  was  then  feized 
with  vomiting,  which  was  after  a  few  periods  fucceededby  purg- 
ing ;  theie  continued  alternately  for  two  hours ;  and  the  purg- 
ing continued  by  intervals  for  fix  or  eight  hours  longer.  Dur- 
ing this  time  he  could  not  force  himfelf  to  drink  more  than  one 
pint  in  the  whole  ;  this  great  inability  to  drink  was  owing  to  the 
naufca,  or  inverted  motions  of  the  ftomach,  which  the  voluntary 
exertion  of  fwallowing  could  feldom  and  with  difficulty  over- 
come; yet  he  difcharged  in  the  whole  at  lead  fix  quarts;  whence 
came  this  quantity  of  liquid  ?  Firft,  the  contents  of  the  ftomach 
were  emitted,  then  of  the  duodenum,  gall-bladder,  and  pancreas, 
by  vomiting.  After  this  the  contents  of  the  lower  bowels  ;  then 
the  chyle,  that  was  in  the  lacleal  vefTels,  and  in  the  receptacle 
of  chyle,  was  regurgitated  into  the  inteftines  by  a  retrograde  mo- 
tion of  thefe  veflels.  And  afterwards  the  mucus  depofited  in  the 
cellular  membrane,  and  on  the  furface  of  all  the  other  mem- 
branes, feems  to  have  been  abforbed  ;  and  with  the  fluid  abforb* 
ed  from  the  air  to  have  been  carried  by  their  refpeclive  lymphat- 
ic branches  by  the  increafed  energy  of  their  natural  motions, 
and  down  the  vifceral  lymphatics,  of  lacleals,  by  the  inverfion  of 
their  motions. 

14.  It  may  be  difficult  to  invent  experiments  to  demonftrate 
the  truth  of  this  inverfion  of  fome  branches  of  the  abforbent  fyf- 
tem,  and  increafed  abforption  of  others  ;  but  the  analogy  of  thefe 
veflels  to  the  inteftinal  canal,  and  the  fymptoms  of  many  difeaf- 
es,  render  this  opinion  more  probable  than  many  other  received 
opinions  of  the  animal  economy. 

In  the  above  inftance,  after  the  yellow  excrement  was  voided, 
the  fluid  ceafed  to  have  any  frriell,  and  appeared  like  curdled 
milk,  and  then  thinner  fluid,  and  fome  mucus,  were  evacuated  : 
did  not  thefe  feem  to  partake  of  the  chyle,  of  the  mucous  fluid 
from  ail  the  cells  of  the  body,  and  laftly,  of  the  atmofpheric  moif- 

ture  ? 


222  OF  THE  STOMACH         SECT.  XXV.  15, 

ture  ?  All  thefe  fads  may  be  eafily  obferved  by  any  one,  who 
takes  a  brifk  purge. 

1 5  Where  the  (limulus  on  the  ftomach,  or  on  fome  other 
part  of  the  inteftinal  canal,  is  dill  more  permanent,  not  only  the 
lacteal  veiTels,  but  the  whole  canal  itfelf,  becomes  inverted  from 
its  aiTociations  ;  this  is  the  iliac  pafTion,  in  which  all  the  fluids 
mentioned  above  are  thrown  up  by  the  mouth.  At  this  time 
the  valve  in  the  colon,  from  the  inverted  motions  of  that  bowel, 
and  the  inverted  adtion  of  this  living  valve,  does  not  prevent  the 
regurgitation  of  its  contents. 

The  (trudture  of  this  valve  may  be  reprefented  by  a  flexile 
leathern  pipe  itanding  up  from  the  bottom  of  a  veflel  of  water  : 
its  fides  coliapfe  by  the  preiTure  of  the  ambient  fluid,  as  a  fmall 
part  of  that  fluid  paffes  through  it;  but  if  it  has  a  living  power, 
and  by  its  inverted  action  keeps  itfelf  open,  it  becomes  like  a 
rigid  pipe,  and  will  admit  the  whole  liquid  to  pafs.  See  Se£t. 
XXXIX.  2.  5. 

In  this  cafe  the  patient  is  averfe  to  drink,  from  the  conflant 
inverfion  of  the  motions  of  the  llomach,  and  yet  many  quarts 
are  daily  eje&ed  from  the  ftomach,  which  at  length  fmell  of  ex- 
crement, and  at  lad  feem  to  be  only  a  thin  mucilaginous  or  aque- 
ous liquor. 

From  whence  is  it  pofSble,  that  this  great  quantity  of  fluid  for 
many  fueceflive  days  can  be  fupplied,  after  the  cells  of  the  body 
have  given  up  their  fluids,  but  from  the  atmofphere  ?  When 
the  cutaneous  branch  of  abforbents  acts  with  unnatural  (Irength, 
it  is  probable  the  inteltinal  branch  has  its  motions  inverted,  and 
thus  a  fluid  is  fupplied  without  entering  the  arterial  fyftem. 
Could  oiling  or  painting  the  fjcin  give  a  check  to  this  difeafe  ? 

So  when  the  ftomach  has  its  morions  inverted,  the  lymphatics 
of  the  ftomach,  which  are  molt  ftridtly  aflbciated  with  it,  invert 
their  motions  at  the  fame  time.  Bu;  the  mere  diftant  branches 
of  lymphatics,  which  are  lefs  ftriftiy  aflbciared  with  it,  act  with 
increased  energy  ;  as  the  cutaneous  lymphatics  in  the  cholera, 
or  iliac  paflion,  above  defcribed.  And  other  irritative  motions 
become  decreafed,  as  the  pulfations  of  the  arteries,  from  the  ex- 
traderivat'oii  or  exhauftion  of  the  fenforial  power. 

Sometimes  when  ftronger  vomiting  takes  place  the  more  dif- 
tant branches  of  the  lymphatic  fyftem  invert  their  motions  with 
thofe  of  the  ftomach,  and  loofe  ftpols  are  produced,  and  cold 
fweats. 

So  when  the  lafteals  have  their  motions  inverted,  as  during 
the  operation  of  ftrong  purges,  the  urinary  and  cutaneous  ab- 
forbents have  their  motions  increafed  to  iupply  the  want  of  flu- 
icjin  the  blood,  as  in  great  thirft  ;  but  after  a  meal  with  fuffi- 

cient 


SECT.  £XV.  1 6.        AND  INTESTINES.  23 

cient  potation  the  urine  is  pale,  that  is,  the  urinary  abforbents 
a£t  weakly,  no  fupply  of  water  being  wanted  for  the  blood. 
And  when  the  inteftinal  abforbents  acl  too  violently,  as  when 
too  great  quantities  of  fluid  have  been  drunk,  the  urinary  abforb- 
ents invert  their  motions  to  carry  off  the  fuperfluity,  which  is 
a  new  circumftance  of  affociation,  and  a  temporary  diabetes  fu- 
pervenes. 

1 6.  I  have  had  the  opportunity  of  feeing  four  patients  in  the 
iliac  paflion,  where  the  ejected  material  fmelled  and  looked  like 
excrement.     Two  of  thefe  were  fo  exhauited  at  the  time  I  faw 
them,  that    more  blood   could   not  be  taken  from  them,  and  as 
their  pain  had    ceafed,  and  they  continued  to  vomit  up  every 
thing  which  they  drank,  I  fufpected  that  a  mortification  of  the 
bowel  had  already  taken   place,  and  as  they  were  both  women 
advanced  in  life,  and  a  mortification  is  produced  with  lefs  pre- 
ceding pain   in    old  and    weak   people,  thefe  both  died.     The 
other  two,  who  were  both  young  men,  had  dill  pain  and  ftrength 
fufficient  for  further  venefeclion,  and  they  neither  of  them  had 
any  appearance  of  hernia,  both  recovered  by  repeated  bleeding, 
and  a  fcruple  of  calomel  given  to  one,  and  half  a  dram  to  the 
other,  in    very   fmall    pills  :  the  ufual   means  of  clyfters,  and 
purges  joined  with  opiates,  had  been  in  vain  attempted.     I  have 
thought  an  ounce  or  two  of  crude  mercury  in  lefs  violent  difeaf- 
es  of  this  kind  has  been  of  ufe,  by    contributing  to  reftore  its 
natural  motion  of  fome  part  of  the  inteftinal  canal,  either  by  its 
weight  or  ftimulus  ;  and  that  hence  the  whole  tube  recovered  its 
ufual  affociations  of    progreflive  periftaitic  motion.     I  have  in 
three  cafes  fecn   crude  mercury  given  in  fmall  dofes,  as  one  or 
two  ounces    twice  a   day,  have  great  effect  in  flopping  pertina- 
cious vomitings. 

17.  Bcfides  the  affections  above  defcribed,  the  ftomach  is  lia- 
ble, like  many  other  membranes  of  the  body,  to  torpor  without 
confequent   inflammation  :  as  happens  to  the  membranes  about 
the  head  in  fome  cafes  of  hemicrania,  or  in  general  head-ach. 
This  torpor  of  the  ftomach  is  attended  with  indigeftion,  and 
consequent  flatulency,  and  with  pain,  which  is  ufually  called  the 
cramp  of  the    ftomach,  and  is  relievable  by  aromatics,  effential 
oils,  alcohol,  or  opium. 

The  intrufion  of  a  gall-ftone  into  the  common  bile-duel  from 
the  gall  bladder  is  fometimes  miftaken  for  a  pain  of  the  ftomach, 
as  neither  of  them  is  attended  with  fever  ;  but  in  the  paffage  of 
a  gali-itone,  the  pain  is  confined  to  a  lei's  fpace,  which  is  exadt- 
ly  where  the  common  bile-duel  enters  the  duodenum,  as  ex- 
plained in  Seel  ion  XXX  3.  Whereas  in  this  gaftrodynia  the 
pain  is  diffufed  over  the  whole  ftomach  5  and,  like  other  difeafes 

from 


224  OF  THE  STOMACH         SECT.  XXV.  17, 

from  torpor,  the  pulfe  is  weaker,  and  the  extremities  colder,  and 
the  general  debility  greater,  than  in  the  paflage  of  a  gall-  ftone  j 
for  in  the  former  the  debility  is  the  confequence  of  the  pain,  in 
the  latter  it  is  the  caufe  of  it, 

.  Though  the  firft  fits  of  the  gout,  I  believe,  commence  with 
a  torpor  of  the  liver  •,  and  the  ball  of  the  toe  becomes  inflamed 
inftead  of  the  membranes  of  the  liver  in  confequence  of  this  tor- 
por, as  a  coryza  or  catarrh  frequently  fucce^:ds  a  long  expofure 
of  the  feet  to  cold,  as  in  fnow,  or  on  a  moift  brick-floor ;  yet  in 
old  or  exhaufted  conftitutions,  which  have  been  long  habituated 
to  its  attacks,  itfometimes  commences  with  a  torpor  of  the  ftom- 
ach, and  is  transferable  to  every  membrane  of  the  body.  When 
the  gout  begins  with  torpor  of  the  ftomach,  a  painful  fenfation 
of  cold  occurs,  which  the  patient  compares  to  ice,  with  weak 
puife,  cold  extremities,  and  ficknefs ;  this  in  its  flighter  degree  is 
relievable  by  fpice,  wine,  or  opium  5  in  its  greater  degree  it  is 
fucceeded  by  fudden  death,  which  is  owing  to  the  fympathy  of 
the  ftomach  with  the  heart,  as  explained  below. 

If  the  ftomach  becomes  inflamed  in  confequence  of  this  gouty 
torpor  of  it,  or  in  confequence  of  its  fympathy  with  fome  oth- 
er part,  the  danger  is  lefs.  A  (icknefs  and  vomiting  continues 
many  days,  or  even  weeks,  the  ftomach  rejecting  every  thing 
ftimulant,  even  opium  or  alcohol,  together  with  much  vifcid 
mucus  ;  till  the  inflammation  at  length  ceafes,  as  happens  when 
other  membranes,  as  thofe  of  the  joinrs,  are  the  ieat  of  gouty 
inflammation  ;  as  obferved  in  Sect.  XXIV.  2.  8, 

The  fympathy,  or  afibciation  of  motions,  between  thofe  of 
the  ftomach  and  thofe  of  the  heart,  is  evinced  in  many  difeaies. 
Firft,  many  people  are  occafionally  affected  with  an  inter  rniffionof 
their  pulfe  for  a  few  days,  which  then  ceafes  again.  In  this  cafe 
there  is  a  ftop  of  the  motion  of  the  heart,  and  at  the  fame  time  a 
tendency  to  eructation  from  the  ftomach.  As  foon  as  the  patient 
feels  a  tendency  to  the  intermiflion  of  the  motion  of  his  heart,  if 
he  voluntarily  brings  up  wind  from  his  ftomach,  the  ftop  of  the 
heart  does  not  occur.  From  hence  I  conclude  that  the  ftop  of  di- 
geftion  is  the  primary  difeaie  ;  and  that  air  is  inftantly  generated 
from  the  aliment,  which  begins  to  ferment,  if  the  digeftive  pro- 
cefs  is  impeded  fora  moment,  (feeSeft.  XXIII.  4  )•,  and  that  the 
ftop  of  the  heart  is  in  confequence  of  the  aflbdatien  of  the  motions 
of  thefe  vifcera,  as  explained  in  Seft.  XXXV.  i.  4.  i  but  if  the 
little  air,  which  is  inftantly  generated  (during  the  temporary  tor- 
por of  the  ftomach,  be  evacuated,  the digeftion  recommences,  and 
the  temporary  torpor  of  the  heart  does  not  follow-  One  patient, 
whom  I  lately  faw,  and  who  had  been  five  or  fix  days  much 
troubled  with  this  intermiflion  of  a  puliation  of  his  heart,  and 

who 


SECT.  XXV.  17.        AND  INTESTINES.  225 

who  had  hemicrania  with  fome  fever,  was  immediately  relieved 
from  them  all  by  lodng  ten  ounces  of  blood,  which  had  what  is 
termed  an  inflammatory  cruft  on  it. 

Another  inftance  of  this  aflbciation  between  the  motions  of 
the  flamach  and  heart  is  evinced  by  the  exhibition  of  an  over 
dofe  of  foxglove,  which  induces  an  inceflant  vomiting,  which  is 
attended  with  very  flow,  and  fometimes  intermitting  pulfe. — 
Which  continues  in  fpite  of  the  exhibition  of  wine  and  opium 
for  two  or  three  days.  To  the  fame  aflbciation  mud  be  afcri- 
bed  the  weak  pulfe,  which  conftantly  attends  the  exhibition  of 
emetics  during  their  operation.  And  alfo  the  fudden  deaths, 
which  have  been  occafioned  in  boxing  by  a  blow  on  the  (torn- 
ach  ;  and  laftly,  the  fudden  death  of  thole,  who  have  been  long 
debilitated  by  the  gout,  from  the  torpor  of  the  ftom ach.  See 
Scft.  XXV.  r.  4. 


VOL.  I.  F  F  SECT. 


22<S  OF  GLANDS.        SECT.  XXVI.  i.  i. 

SEC  T.       XXVI. 

01-     THE    CAPILLARY  GLANDS  AND   MEMBRANES. 

I.  i ,  The  capillary  vejjels  are  glands.  2.  Their  excretory  duels. 
Experiments  on  the  mucus  of  the  intejlines^  abdomen ,  cellular  mem- 
brajiey  and  on  the  humours  of  the  eye.  3.  Scurf  on  the  head,  cough, 
catarrh^  diarrhoea^  gonorrhoea.  4.  Rheumatifm.  Gout.  JLep~ 
rofy.  II.  i.  The  moft  minute  membranes  are  unorganized.  2. 
Large  membranes  are  compofed  of  the  duffs  of  the  capillaries^  and 
the  mouths  of  the  abfor bents.  3,  Mucilaginous  fluid  is  fecreted 
on  their  furf ace.  III.  Three  kinds  of  rheumatifm. 

1.  r.  THE  capillary  vefTels  are  like  all  the"other  glands  except 
the  abforbent  fyflern,  inafmuch  as  they  receive  blood  from  the 
arteries,  feparate  a   fluid  from  it,  and  return  the  remainder  by 
the  veins. 

2.  This  feries  of  glands  is  of  the  mod  extenfive  ufe,  as  their 
excretory  dufts  open  on  the  whole  external  fkin  forming  its  per- 
fpirative  pores,   and  on  the  internal  furfaces  of  every  cavity  of 
the  body.     Their  fecretionon  the  fkin  is  termed  infenfible  per- 
fpiration,  which   in  health  is  in  part  reabforbed  by  the  mouths 
of  the   lymphatics,  and  in  part  evaporated  in  the  air  ;  the  fecre- 
tion  on  the  membranes,    which  line  the  larger  cavities  of  the 
body,  which  have  external  openings,  as  the  mouth  and  inteftinai 
canal,  is  termed  mucus,  but  is  not  however  coagulable  by  heat ; 
and  the  fecretion  on  the  membranes  of  thofe  cavities  of  the  body, 
which  have  no  external    openings,  is  called  lymph  or  water,  as 
in  the  cavities  of  the  cellular  membrane,  and  of  the  abdomen  ; 
this  lymph  however  is  coagulable  by  the  heat  of  boiling  water. 
Some  mucus  nearly  as  vifcid  as  the  white  of  egg,  which  was  dif- 
charged  by  (tool,  did  not  coagulate,  though  I  evaporated  it  to  one 
fourth  of  the  quantity,  nor  did  the  aqueous  and  vitreous  humours 
of  a  (heep's  eye   coagulate  by  the  like  experiment  j  but  the  fe- 
rofity  from  an  anafarcous  leg,    and  that  from   the  abdomen  of  a 
dropfical  perfon,   and  the  cryftaliine  humour  of  a  Iheep's  eye, 
coagulated  in  the  fame  heat. 

3.  When  any  of  thefe  capillary  glands  are  ftimulated  into 
greater  irritative  actions,  than  is  natural,  they  lecrete  a  more 
copious  material  ;  and  as  the  'mouths  of  the  abforbent  fyftem, 
which  open  in  their  vicinity,  are  at  the  fame  time  ftimulated  in- 
to greater  action,  the  thinner  and  more  faline  part  of  the  fecre- 
ted fluidf  is  taken  up  again  :  and  the  remainder  is  not  only  mere 
copious  but  alfo  more  vifcid  than  natural.  This  is  more  or  lefs 

troublefome 


SECT.  XXVI.  i.  4.         OF  GLANDS.  227 

troublefome  or  noxious  according  to  the  importance  of  the  func- 
tions of  the  part  affected  :  on  the  fkin  and  bronchise,  where.^this 
fecretion  ought  naturally  to  evaporate,  it  becomes  fo  vifcid  as  to 
adhere  to  the  membrane  ;  on  the  tongue  it  forms  a  pellicle, 
which  can  with  difficulty  be  fcraped  off  j  produces  the  fcurf  on 
the  heads  of  many  people  ;  and  the  mucus,  which  is  fpit  up  by 
others  in  coughing.  On  the  noftrils  and  fauces,  when  the  fe- 
rretion  of  thefe  capillary  glands  is  increafed,it  is  termed  fimple 
catarrh  •,  when  in  the  intedines,  a  mucous  diarrhoea ;  and  in  the 
urethra,  or  vagina,  it  has  the  name  of  gonorrhoea,  or  fluor  albus. 

4.  When  thefe  capillary  glands  become  inflamed,  a  dill  more 
vifcid  or  even  cretaceous  humour  is  produced  upon  the  furfaccs 
of  die  membranes,  which  is  the  caufe  or  the  effect  of  rheumat- 
ifm,  gout,  leprofy,  and  of  hard  tumours  of  the  legs,  which  are 
generally  termed  fcorbutic  ;  all  which  will  be  treated  of  here- 
after. 

II.  i.  The  whole  furface  of  the  body,  with  all  its  cavities  and 
contents,  are  covered  with  membrane.  It  lines  every  veflel, 
forms  every  cell,  and  binds  together  all  the  mufcular  and  per- 
haps the  offcous  fibres  of  the  body  ;  and  is  itfelf  therefore  prob- 
ably a  fimpler  fubftance  than  thofe  fibres.  And  as  the  contain- 
ing veflels  of  the  body  from  the  largeft  to  the  lead  are  thus  lined 
and  connected  with  membranes,  it  follows  that  thefe  membranes 
themfelves  confid  of.  unorganized  materials. 

For  however  fmall  we  may  conceive  the  diameters  of  the 
minuted  veflels  of  the  body,  which  efcape  our  eyes  and  glafles, 
yet  thefe  veflels  mud  confid  of  coats  or  fides,  which  are  made 
up  of  an  unorganized  material,  and  which  are  probably  produ- 
ced from  a  gluten,  which  hardens  after  its  production,  like  the 
filk  or  web  of  caterpillars  and  fpiders.  Of  this  material  confid 
the  membranes,  which  line  the  (hells  of  eggs,  and  the  (hell  itfelf, 
both  which  are  unorganized,  and  are  formed  from  mucus,  which 
hardens  after  it  is  formed,  either  by  the  abforption  of  its  more 
fluid  part,  or  by  its  uniting  with  fome  part  of  the  atmofphere. 
Such  is  alfo  the  production  of  the  (hells  of  fnails,  and  of  (hell- 
fifh,  and  I  fuppofe  of  the  enamel  of  the  teeth. 

2.  But  though  the  membranes,  that  compofe  the  fides  of  the 
mod  minute  veflels,  are  in  truth  unorganized  materials,  yet  the 
larger  membranes,  which  are  perceptible  to  the  eye,  feem  to  be 
compofed  of  an  intertexture  of  the  mouths  of  the  abforbent  fyf- 
tem,  and  of  the  excretory  ducts  of  the  capillaries,  with  their  con- 
comitant arteries,  veins  and  nerves  :  and  from  this  condruction 
it  is  evident,  that  thefe  membranes  mud  poflcfs  great  irritability 
to  peculiar  dimuli,  though  they  are  incapable  of  any  motions, 
that  are  vifible  to  the  naked  eye  :  and  daily  experience  (hews  us, 

that 


22$  OF  GLANDS.         SECT.  XXVI.  2.  3. 

that  in  their  inflamed  ftate  they  have  the^  greatefl  fenfibility  to 
pain,  as  in  the  pleurify  and  paronychia. 

3  On  all  thefe  membranes  a  mucilaginous  or  aqueous  fluid  is 
fecreted,  which  moiftens  and  lubricates  their  furfaces,  as  was 
explained  in  Section  XXIII.  2.  Some  have  doubted,  whether 
this  mucus  is  feparated  from  the  blood  by  an  appropriated  fet  of 
glands,  or  exudes  through  the  membranes,  or  is  an  abraiion  or 
deftruclion  of  the  furface  of  the  membrane  itfelf,  which  is  con- 
tinually repaired  on  the  other  fide  of  it,  but  the  great  analogy 
between  the  capillary  veflels,  and  the  other  glands,  countenances 
the  former  opinion  ;  and  evinces,  that  thefe  capillaries  are  the 
glands,  that  fecrete  it ;  to  which  we  muft  add,  that  the  blood  iri 
paffing  thefe  capillary  veflels  undergoes  a  change  in  its  colour 
from  florid  to  purple,  and  gives  out  a  quantity  of  heat ;  from 
whence,  as  in  other  glands,  we  muft  conclude  that  fomething 
is  fecreted  from  it. 

III.  The  feat  of  rheumatifm  is  in  the  membranes,  or  upon 
them  ;  but  there  are  three  very  diftinfl:  difeafes,  which  com- 
monly are  confounded  under  this  name.  Firft,  when  a  mem- 
brane becomes  affefted  with  torpor  or  inactivity  of  the  veflels 
which  compofe  it,  pain  and  coldnefs  fucceed,  as  in  the  hemicra- 
nia,  and  other  head-achs,  which  are  generally  termed  nervous 
rheumatifm  ;  they  exift  whether  the  part  be  at  reft  or  in  motion, 
and  are  generally  attended  with  other  marks  of  debility. 

Another  rheumatifm  is  faid  to  exift,  when  inflammation  and 
fwelling,  as  well  as  pain,  afTecl  fome  of  the  membranes  of  the 
joints,  as  of  the  ancles,  wrifts,  knees,  elbows,  and  fometimes  of 
the  ribs.  This  is  accompanied  with  fever,  is  analogous  to  pleu- 
rify and  other  inflammations,  and*  is  termed  the  acute  rheu- 
matifm. 

A  third  difeafe  is  called  chronic  rheumatifm,  which  is  diftin- 
guifhed  from  that  firft  mentioned,  as  in  this  the  pain  only  af- 
fefts  the  patient  during  the  motion  of  the  part,  and  from  the 
fecond  kind  of  rheumatifm  above  defcribed,  as  it  is  not  attend- 
ed with  quick  pulfe  or  inflammation.  It  is  generally  believed 
to  fucceed  the  acute  rheum  at  iim  of  the  fame  part,  and  that  fome 
coagulable  lymph,  or  cretaceous,  or  calculous  material,  has 
been  left  on  the  membrane  ;  which  gives  pain,  when  the  muf- 
cles  move  over  it,  as  fome  extraneous  body  would  do,  which  was 
too  infoluble  to  be  abforbed.  Hence  there  is  an  analogy  be- 
tween this  chronic  rheumatifm  and  the  difeafes  which  produce 
gravel  or  gout>  ftones  ;  and  it  may  perhaps  receive  relief  from 
the  fame  remedies,  fuch  as  aerated  fal  foda. 


SECT, 


SECT.  XXVII.  i.  i.  OF  HAEMORRHAGES.  229 

SECT.       XXVII. 

OF    HAEMORRHAGES. 

I.  The  veins  are  abforbent  vejfels.  I.  Hemorrhages  from  inflam- 
mation. Cafe  oj  hemorrhage  from  the  kidney  cured  by  cold  bathing. 
Cafe  of  hemorrhage  from  the  nofe  cured  by  cold  immerjion.  II. 
Hemorrhage  from  venous  paralyfis.  Of  Piles.  Black  fools. 
Petechie  Confumption.  Scurvy  of  the  lungs.  Blacknefs  of  the 
face  and  eyes  in  epileptic  Jits.  Cure  of  hemorrhages  from  venous 
Inability. 

I.  As  the  imbibing  mouths  of  the  abforbent  fyftem  already 
defcribed  open  on  the  furface,  and  into  the  larger  cavities  of  the 
body,  fo  there  is  another  fyftem  of  abforbent  veflels,  which  arc 
not  commonly  efteemed  fuch,  I  mean  the  veins,  which  take  up 
the  blood  from  the  various  glands  and  capillaries,  after  their  prop- 
er fluids  or  fecretions  have  been  feparated  from  it. 

The  veins  refemble  the  other  abforbent  veflels  ;  as  the  progref- 
fion  of  their  contents  is  carried  on  in  the  fame  manner  in  both, 
they  alike  abforb  their  appropriated  fluids,  and  have  valves  to 
prevent  its  regurgitation  by  the  accidents  of  mechanical  vio- 
lence. This  appears  firft,  becaufe  there  is  no  pulfation  in  the 
very  beginnings  of  the  veins,  as  is  feen  by  microfcopes  ;  which 
mull  happen,  if  the  blood  was  carried  into  them  by  the  actions 
of  the  arteries.  For  though  the  concurrence  of  various  venous 
flreams  of  blood  from  different  diftances  muft  prevent  any  pul- 
fation in  the  larger  branches,  yet  in  the  very  beginnings  of  all 
thefe  branches  aFpulfation  muft  unavoidably  exift,  if  the  circula- 
tion in  them  was  owing  to  the  intermitted  force  of  the  arteries, 
Secondly,  the  venous  abforption  of  blood  from  the  penis,  and 
from  the  teats  of  female  animals  after  their  erection,  is  ftill  more 
fimilar  to  the  lymphatic  abforption,  as  it  is  previoufly  poured  in- 
to cells,  where  all  arterial  impulfe  muft  ceafe, 

There  is  an  experiment,  which  feems  to  evince  this  venous 
abforption,  which  confifts  in  the  external  application  of  a  ftimu- 
lus  to  the  lips,  as  of  vinegar,  by  which  they  become  inftantly 
pale  ;  that  is,  the  bibulous  mouths  of  the  veins  by  this  ftimulus 
are  excited  to  abforb  the  blood  fafter,  than  it  can  be  fupplied  by 
the  ufual  arterial  exertion.  See  Seel.  XXIII.  5. 

i.  There  are  two  kinds  of  haemorrhages  frequent  in  difeafes, 
one  is  where  the  glandular  or  capillary  action  is  too  powerfully  ex- 
erted, and  propels  the  blood  forwards  more  haftily,  than  the 
veins  can  abforb  it ;  and  the  other  is,  where  the  abforbent  pow- 
er 


OF  HAEMORRHAGES.    SECT.  XXVII.  i.  i, 

of  the  veins  is  diminifiied,  or  a  branch  of  them  is  become  to* 
tally  paralytic. 

The  former  of  thefe  cafes  is  known  by  the  heat  of  the  part, 
and  the  general  fever  or  inflammation  that  accompanies  the  haem- 
orrhage A  haemorrhage  from  the  nofe  or  from  the  lungs  is 
fometimes  a  crifis  of  inflammatory  difeafes,  as  of  the  hepatitis 
and  gout,  and  generally  ceafes  fpontaneoufly,  when  the  vefiels 
are  confidently  emptied.  Sometijp.es  the  haemorrhage  recurs 
by  daily  periods  accompanying  the  hot  fits  of  fever,  and  ceafing 
m  the  ccld  fits,  or  in  the  intei  mi/lions  ;  this  is  to  be  cured  by  re- 
moving the  febrile  paroxyfms,  which  will  be  treated  of  in  their 
place.  Otherwife  it  is  cured  by  venesection,  by  the  internal  or 
external  preparations  of  lead,  or  by  the  application  of  cold,  with 
an  abftemious  diet,  and  diluting  liquids,  likeotht'r  inflammations. 
Which  by  inducing  a  quiefcence  on  thole  glandular  parts,  that 
are  affefted,  prevents  a  greater  quantity  of  blood  from  being 
protruded  forwards,  than  the  veins  are  capable  of  abforbing. 

Mr.  B had  a  haemorrhage  from  his  kidney,  and  parted 

with  not  lefs  than  a  pint  of  blood  a  day  (by  conjecture)  along 
with  his  urine  for  above  a  fortnight :  venefe&ions,  mucilages, 
balfams,  preparations  of  lead,  the  bark,  alum,  and  dragon's 
blood,  opiates,  with  a  large  biiftcr  on  his  loins,  were  feparaiely 
tried,  in  large  dofes,  to  mo  purpofe.  He  was  then  dire&ed  to 
bathe  in  a  cold  fpring  up  to  the  middle  of  his  body  only,  the  up- 
per part  being  covered,  and  the  haemorrhage  diminifhed  at  the 
firft,  and  ceafcd  at  the  fecond  immerfion. 

In  this  cafe  the  external  capillaries  were  rendered  quiefcent  by 
the  coldneis  of  the  water,  and  thence  a  lefs  quantity  of  blood 
was  circulated  through  them  ;  and  the  internal  capillaries,  or 
other  glands,  became  quiefcent  from  their  irritative  aflbciations 
with  the  external  ones  ;  and  the  haemorrhage  was  flopped  a 
fufEcient  time  for  the  ruptured  vefiels  to  contract  their  aper- 
tures, or  for  the  blood  in  thofe  apertures  to  coagulate. 

Mrs.  K had  a  continued  haemorrhage  from  her  nofe 

for  fomedays  ;  the  ruptured  vefTel  was  not  to  be  reached  by 
plugs  up  the  noftrils,  and  the  fenfibility  of  her  fauces  was  fuch 
that  nothing  could  be  borne  behind  the  uvula.  After  repeated 
venefeftion,  and  other  common  applications,  fhe  was  directed 
to  immerfe  her  whole  head  into  a  pail  of  water,  which  was 
made  colder  by  the  addition  of  feveral  handfuls  of  fait,  and  the 
haemorrhage  immediately  ceafed,  and  returned  no  more  ;  but 
her  pulfe  continued  hard,  and  fhe  was  neceflitated  to  lofe  blood 
from  the  arm  on  the  fucceeding  day. 

Query,  might  not  the  cold  bath  inftantly  (lop  haemorrhages 
from  the  lungs  in  inflammatory  cafes  ? — for  the  fhortnefs  of 

breath 


SECT.  XXVII.  2.  i.     OF  HEMORRHAGES.  231 

breath  of  thofe,  who  go  fuddenly  into  cold  water,  is  not  owing 
to  the  accumulation  of  blood  in  the  lungs,  but  to  the  quiefcence 
of  the  pulmonary  capillaries  from  aflbciation,  as  explained  in 
Sedion  XXXII.  3.  2. 

II.  The  other  kind  of  haemorrhage  is  known  from  its  being  at- 
tended with  a  weak  pulfe,and  other  fymptoms  of  general  debil- 
ity, and  very  frequently  occurs  in  thofe,  who  have  difeafecl  livers, 
owing  to  intemperance  in  the  ufe  of  fermented  liquors.  Thefe 
conftitutions  are  (hewn  to  be  liable  to  paralyiis  of  the  lymphatic 
abforbents,  producing  the  various  kinds  of  dropfies  in  Sedtion 
XXIX.  5.  Now  if  any  branch  of  the  venous  fyftem  lofes  its 
power  of  abforption,  the  part  fvvells,  and  at  length  burfts  and 
difcharges  the  blood,  which  the  capillaries  or  other  glands  cir- 
culate through  them. 

It  fometirnes  happens  that  the  large  external  veins  of  the  legs 
burft,  and  eftufe  their  blood  ;  but  this  occurs  molt  frequently  in 
the  veins  of  the  inteflines,  as  the  vena  portarum  is  liable  to  fuf- 
fer  from  a  fchirrus  of  the  liver  oppofing  the  progreflion  of  the 
blood,  which  is  abforbed  from  the  interlines.  Hence  the  piles 
are  a  fymptom  of  hepatic  obltruclion,  and  hence  the  copious 
difcharges  downwards  or  upwards  of  a  black  material,  which 
has  been  called  melancholia,  or  black  bile  ;  but  is  no  oi  her  than 
the  blood,  which  is  probably  difcharged  from  the  veins  of  the 
inte  (lines. 

J.F.Msckel,  in  his  Experiments  deFinibus  Vaforum,publiflied 
at  Berlin,  1772,  mentions  his  difcovery  of  a  communication  of 
a  lymphatic  veflel  with  the  gaftric  branch  of  the  vena  portarum. 
It  is  poflible,  that  when  the  motion  of  the  lymphatic  becomes 
retrograde  in  jfome  difeafes,  blood  may  obtain  a  paflage  into  it, 
where  it  anaftomofes  with  the  vein,  and  thus  be  poured  into  the 
inteitines.  A  difcharge  of  blood  with  the  urine  fometirnes  at- 
tends diabetes,  and  may  have  its  fource  in  the  fame  manner. 

Mr.  A ,  who  had  been  a  hard  drinker,  and  had  the 

gutta  rofacea  on  his  face  and  bread,  after  a  (broke  of  the  palfy 
voided  near  a  quart  of  a  black  vifcid  material  by  ftool  :  on  di- 
luting it  with  water  it  did  not  become  yellow,  as  it  muft  have 
done  if  it  had  been  infpiflated  bile,  but  continued  black  like  the 
grounds  of  coffee. 

But  any  other  part  of  the  venous  fyftem  may  become  quiefcent 
or  totally  paralytic  as  well  as  the  veins  of  the  inteftines:  all  which 
occur  more  frequently  in  thofe  who  have  difeafed  livers,  than  in 
any  others.  Hence  troublefome  bleedings  of  the  nofe,  or  from  the 
lungs  with  a  weak  pulfejhsnce  haemorrhages  from  the  kidneys, 
too  great  menftruation  ;  and  hence  the  oozing  of  blood  from 
every  part  of  the  body,  and  the  petechiae  in  thofe  fevers,  which 

are 


23.2  OF  HEMORRHAGES.    SECT.  XXVII.  2.  i. 

are  termed  putrid,  and  which  is  erroneouflv  afcribed  to  the  thin- 
nefs  of  the  blood  :  for  the  blood  in  inflammatory  difeafes  is 
equally  fluid  before  it  coagulates  in  the  cold  air. 

Is  not  that  hereditary  confumption,  which  occurs  chiefly  in 
darkeyed  people  about  the  age  of  twenty,  and  commences 
with  flight  pulmonary  haemorrhages  without  fever,  a  difeafe  of 
this  kind  ? — Thefe  hasmorrages  frequently  begin  during  fleep, 
when  the  irritability  of  the  lungs  is  not  fufficient  in  thefe  patients 
to  carry  on  the  circulation  without  the  affiftance  of  volition  ;  for 
in  our  waking  hours,  the  motions  of  the  lungs  are  in  part  volun- 
tary, efpecially  if  any  difficulty  of  breathing  renders  the  efforts 
of  volition  neceflary.  See  Clafs  I.  2.  I.  3  and  Clafs  III.  2.  i. 
j-2.  Another  fpecies  of  pulmonary  confumption  which  feems 
more  certainly  of  icrofulous  origin  is  defcribed  in  the  next  Sec- 
tion, No  2. 

I  have  feen  two  cafes  of  women,  of  about  forty  years  of  age, 
both  of  whom  were  feized  with  quick  weak  pulfe,  with  difficult 
refpiration,  and  who  fpit    up  by  coughing  much  vifcid  mucus 
mixed  with  dark  coloured  blood.     They  had  both  large  vibices 
on  their  limbs,  and  petechiae  ;  in  one  the  feet  were  in  danger  of 
mortification,  in  the  other  the  legs  were  cedematous.    To  relieve 
the  difficult  refpiration,   about  fix  ounces  of  blood  were  taken 
from  one  of  them,  which  to  my  furpife  was  fizy,  like  inflamed 
blood  :   they  had  both  palpitations  or  unequal  pulfations  of  the 
heart.     They  continued  four  or  five  weeks  with  pale  and  bloat- 
ed countenances,  and  did  pot  ceafe  fpitting  phlegm  mixed  with 
black  blood,  and  the  pulfe  feldom  flower  than  130  or  135  in  a 
minute.     This  blood,  from  its  dark  colour,  and  from  the  many 
vibices  and   petechise,  feems  to  have  been  venous  blood  ;  the 
quicknefs  of  the  pulfe,  and  the  irregularity  of  the  motion  of  the 
heart,  are  to   be  afcribed  to  debility  of  that  part  of  the  fyftem  ; 
as  the  extravafation  of  blood  originated  from  the  defect  of  ven- 
ous abforption.     The  approximation  of  thefe  two  cafes  to  fea- 
fcurvy  is  peculiar,  and    may   allow  them  to  be  called  fcorbutus 
pulmonalis.     Had  thefe  been  younger  fubjecls,  and  the  paraly- 
fis  of  the  veins  had  only  affected  the  lungs,  it  is  probable  the 
difeafe  would  have  been  a  pulmonary  confumption. 

Laft  week  I  faw  a  gentleman  of  Birmingham,  who  had  for 
ten  days  laboured  under  great  palpitation  of  his  heart,  which 
was  fo  diftindtly  felt  by  the  hand,  as  to  difcountenance  the  idea 
of  there  being  a  fluid  in  the  pericardium.  He  frequently  fpit 
up  mucus  ftained  with  dark  coloured  blood,  his  pulfe  very  un- 
equal and  very  weak,  with  cold  hands  and  noife.  He  could  not 
lie  down  at  all,  and  for  about  ten  days  pad  could  not  fleep  a  min- 
ute together,  but  waked  perpetually  with  great  uneafmefs* 

Could 


SECT.  XXVII.  2.  i.    OF  HAEMORRHAGES.  233 

Could  thofe  fymptoms  be  owing  to  very  extenflve  adhefions  of 
the  lungs  ?  or  is  this  a  fcorbutus  pulmonalis  ?  After  a  few  days 
he  fuddenly  got  fo  much  better  as  to  be  able  to  fleep  many  hours 
at  a  time  by  the  ufe  of  one  grain  of  powder  of  foxglove  twice  a 
day,  and  a  grain  of  opium  at  night.  After  a  few  days  longer,  the 
bark  was  exhibited,  and  the  opium  continued  with  fome  wine  ; 
and  the  palpitations  of  his  heart  became  much  relieved,  and  he 
recovered  his  ufual  degree  of  health,  but  died  fuddenly  fome 
months  afterwards. 

In  epileptic  fitsthe  patients  frequently  become  blackin  the  face, 
from  the  temporary  paralyfis  of  the  venous  fyftem  of  this  part. 
I  have  known  two  inltances  where  the  blacknels  has  continued 

many  days.  M.  P ,  who  had  drank  intemperately,  was 

feized  with  the  epilepiy  when  he  was  in  his  fortieth  year  ;  in 
one  of  theie  fits  the  white  part  of  his  eyes  was  left  totally  black 
with  efFufed  blood  ;  which  was  attended  with  no  pain  or  heat, 
and  was  in  a  few  weeks  gradually  abforbed,  changing  colour  as 
is  ufual  with  vibices  from  bruifes. 

The  haemorrhages  produced  from  the  inability  of  the  veins  to 
abforb  the  refluent  blood,  are  cured  by  opium,  the  preparations 
of  fteel,  lead,  the  bark,  vitriolic  acid,  and  bliiters;  but  thefe  have 
the  effect  with  much  more  certainty,  if  a  venefedlion  to  a  few 
ounces,  and  a  moderate  cathartic  with  four  or  fix  grains  of  cal- 
omel be  premifed,  where  the  patient  ib  not  already  too  much 
debilitated  ;  as  one  great  means  of  promoting  the  abforption  of 
any  fluid  confifts  in.  previoufly  emptying  the  veffels,  which  are 
to  receive  it. 


VOL,  t  .(,'  r:  SEC'l 


234  PARALYSIS  OF        SECT.  XXVIII.  i. 

SECT.      XXVIII. 

OF    THE    PARALYSIS    OF    THE    ABSORBENT    SYSTEM. 

I.  Paralyfts  of  the  laEleals^  atrophy.  Diftajle  to  animal  food.     II. 

Caufe  of  dropfy.      Caufe  of  herpes.  Scrofula.      Mefenteric  con- 

fumption.     Pulmonary  confumption.  Why  ulcers  in  the  lungs  are 
fo  difficult  to  heal. 

THE  term  paralyfishas  generally  been  ufed  to  exprefs  the  lofs 
of  voluntary  motion,  as  in  the  hemiplegia,  but  may  with  equal 
propriety  be  applied  to  exprefs  the  difobediency  of  the  mufcu- 
lar  fibres  to  the  other  kinds  of  ftimulus  ;  as  to  thofe  of  irritation 
or  fenfation. 

I.  There  is  a  fpecies  of  atrophy,  which  has  not  been  well  un- 
derftood  ;  when  the  abforbent  veiTels  of  the  ftomach  and  intef- 
tines  have  been  long  inured  to  the  ftimulus  of  too  much  fpirit- 
uous  liquor,  they  at  length,  either  by  the  too  fudden  omiffion  of 
fermented  or  fpirituous  potation,  or  from  the  gradual  decay  of 
nature,  become  in  a  certain  degree  paralytic  ;  now  it  is  obferv- 
ed  in  the  larger  mufcles  of  the  body,  when  one  fide  is  paralytic, 
the  other  is  more  frequently  in  motion,  owing  to  the  lefs  expen- 
diture of  fenforial  power  in  the  paralytic  limbs  \  fo  in  this  cafe 
the  other  part  of  the  abforbent  fyftem  afts  with  greater  force, 
or  with  greater  perfeverance,  in  confequence  of  the  paralyfis  of 
the  la&eals  ;  and  the  body  becomes  greatly  emaciated  in  a  fmall 
time. 

I  have  feen  feveral  patients  in  this  difeafe,  of  which  the  fol- 
lowing are  the  circum fiances.  I.  They  were  men  about  fifty 
years  of  age,  and  had  lived  freely  in  refpecl  to  fermented  liquors. 
2.  They  loft  their  appetite  to  animal  food,  3.  They  became 
fuddenly  emaciated  to  a  great  degree.  4.  Their  fkins  were  dry 
and  rough.  5.  They  coughed  and  expectorated  with  difficulty 
a  vifcid  phlegm.  6.  The  membrane  of  the  tongue  was  dry 
and  red,  and  liable  to  become  ulcerous. 

The  inability  to  digeft  animal  food,  and  the  confequent  dif- 
tafte  to  it,  generally  precede  the  dropfy,  and  other  difeafes, 
which  originate  from  fpirituous  potation.  I  fuppofe  when  the 
ftomach  becomes  inirritable,  that  there  is  at  the  fame  time  a  de- 
ficiency of  gaftric  acid  ;  hence  milk  feldom  agrees  with  thefe 
patients,  unlefs  it  be  previoufly  curdled,  as  they  have  not  fuffi- 
cient  gaftric  acid  to  curdle  it ;  and  hence  vegetable  food,  which 
is  itfelf  acefcent,  .will  agree  with  their  ftomachs  longer  than  an- 
imalfood,  which  requires  more  of  the  gaftric  acid  forits  digeftion. 

In 


SECT.  XXVIII.  2.          ABSORBENTS.  235 

In  this  difeafe  the  fkin  is  dry  from  the  increafed  abrorption  of 
the  cutaneous  lymphatics,  the  fat  is  abforbed  from  the  increafed 
abforption  of  the  cellular  lymphatics,  the  mucus  of  the  lungs 
is  too  vifcid  to  be  eafily  fpit  up  by  the  increafed  abforption  of 
the  thinner  parts  of  it,  the  membrana  fneideriana  becomes  dry, 
covered  with  hardened  mucus,  and  at  length  becomes  inflamed 
and  full  of  apthx,  and  either  thefe  floughs,  or  pulmonary  ulcers, 
terminate  the  fcene. 

II.  The  immediate  caufe  of  dropfy  is  the  paralyfiS  of  fome 
other  branches  of  the  abforbent  fyftem,  which  are  called  lym- 
phatics, and  which  open  into  the  larger  cavities  of  the  body,  or 
into  the  cells  of  the  cellular  membrane ;  whence  thofe  cavities 
or  cells  become  diftended  with  the  fluid,  which  is  hourly  fecre- 
ted  into  them  for  the  purpofe  of  lubricating  their  furfaccs.  As 
is  more  fully  explained  in  No.  5.  of  the  next  Se6tion. 

As  thofe  lymphatic  veflels  confift  generally  of  a  long  neck  or 
mouth,  which  drinks  up  its  appropriated  fluid,  and  of  a  conglob- 
ate gland,  in  which  this  fluid  undergoes  fome  change,  it  hap- 
pens, that  fometimesthe  mouth  of  the  lymphatic,  and  fometimes 
the  belly  or  glandular  part  of  it,  becomes  totally  or  partially  par- 
alytic. In  the  former  cafe,  where  the  mouths  of  the  cutaneous 
lymphatics  become  torpid  or  quiefcent,  the  fluid  fecreted  on  the 
fkin  ceafes  to  be  abforbed,  and  erodes  the  fkin  by  its  faline  acri- 
mony, and  produces  eruptions  termed  herpes,  the  difcharge  from 
which  is  as  fait,  as  the  tears,  which  are  fecreted  too  faft  to  be  reab- 
forbed,  as  in  grief,  or  when  the  punfta  lacrymalia  are  obftrudted, 
and  which  running  down  the  cheek  redden  and  inflame  the  fkin. 

When  the  mouths  of  the  lymphatics,  which  open  on  the  mu- 
cous membrane  of  the  noftrils,  become  torpid,  as  on  walking 
into  the  air  in  a  frofty  morning  ;  the  mucus,  which  continues 
to  be  fecreted,  has  not  its  aqueous  and  faline  part  reabforbed 
which  running  over  the  upper  lip  inflames  it,  and  has  a  fait 
tafte,  if  it  falls  on  the  tongue 

When  the  belly,  or  glandular  part  of  one  of  thefe  lymphatics, 
becomes  torpid,  the  fluid  abforbed  by  its  mouth  flagnates,  and 
forms  a  tumour  in  the  gland.  This  difeafe  is  called  the  fcrofula. 
If  thefe  glands  fuppurate  externally,  they  gradually  heal,  as  thofe 
of  the  neck  ;  if  they  fuppurate  without  an  opening  on  the  ex- 
ternal habit,  as  the  mefenteric  glands,  a  heftic  fever  enfues, 
which  deftroys  the  patient;  if  they  fuppurate  in  the  lungs,  a 
pulmonary  confumption  enfues,  which  is  believed  thus  to  differ 
from  that  defcribed  in  the  preceding  Seftion,  in  refpett  to  its 
feat  or  proximate  caufe. 

It  is  remarkable,  that  matter  produced  by  fuppuration  will  lie 
concealed  in  the  body  many  weeks>  or  even  months,  without  pro- 
ducing 


236  PARALYSIS   OF          SECT.  XXVIIl.  2. 

ducing  he&ic  fever  ;  but  as  focn  as  the  wound  is  opened,  fo  as 
to  admit  air  to  the  furface  of  the  ulcer,  a  hedlic  fever  fupervenes, 
even  in  very  few  hours,  which  I  formerly  conceived  to  be  owing 
to  the  azotic  part  of  the  atmofphere  rather  than  to  the  oxy- 
gene  ;  becaufe  thofe  medicines,  which  contain  much  oxygene, 
as  the  calces  or  oxydes  of  metals,  externally  applied*  greatly 
contribute  to  heal  ulcers  ;  as  thefe  are  the  folutions  of  lead,  and 
mercury,  and  copper  in  acids,  or  their  precipitates  ;  but  have 
fince  believed  it  owing  to  the  oxygene.  See  Clafs  II.  i.  6.  7. 
in  Vol.  II.  of  this  work. 

Hence  when  wounds  are  to  be  healed  by  the  firft  intention, 
as  it  is  called,  it  is  neceflary  carefully  to  exclude  the  air  from 
them.  Hence  we  have  one  caufe,  which  prevents  pulmonary 
ulcers  from  healing,  which  is  their  being  perpetually  expofcd  to 
the  air. 

Another  caufe  of  the  difficulty  of  healing  pulmonary  ulcers 
may  arife  from  the  inactivity  of  the  veflelsof  the  air-cells,  which 
are  covered  with  a  membrane  differing  both  from  that  of  the  mu- 
cous membranes  of  other  cavities  of  the  body,  and  from  the  ex- 
ternal (kin.  For  it  is  probable,  that  the  air-cells  alone  of  the 
lungs  conftitutethe  organ  of  refpiration,  and  not  the  internal  fur- 
faces  of  the  branching  vefTels  of  the  trachea  which  lead  to  the 
air-cells.  And  from  a  vegetable  analogy  mentioned  below  they 
probably  exhale  or  perfpire  either  nothing  or  much  lefs  than  the 
Surfaces  of  the  pulmonary  veffels,  which  lead  to  them  Hence 
the  mucus,  which  in  common  coughs  or  fuperficial  peripneumo- 
ny  is  fecreted  on  the  furface  of  the  branching  vefTels  of  the  lungs, 
is  forced  up  in  coughing  ^by  the  air  behind  it,  which  ishaftily 
excluded  from  the  air-cells,  and  flowly  inhaled  into  them.  But 
if  there  was  any  mucus  or  matter  formed  in  thefe  air-cells,  it  is 
not  eafy  to  underftand  how  it  could  be  brought  up  by  coughing, 
as  no  air  could  get  admittance  behind  it  ;  which  may  be  one 
caufe  of  the  difficulty  of  healing  pulmonary  ulcers  if  they  exift 
on  the  furface  of  the  air-cells  ;  but  not  fo,  if  they  exift  in  the 
veflels  leading  to  the  air-cells,  as  after  a  wound  with  a  fword, 
or  when  a  vomica  has  burft  after  a  peripneumony. 

In  the  vegetable  fyftem,  I  think,  there  can  be  no  doubt,  but 
that  the  upper  furface  of  the  leaves  conftitutes  the  organ  of  ref- 
piration, and  M.  Bonnet  in  his  Ufage  des  Feuilles  (hows  by  a 
curious  experiment,  that  the  upper  furfaces  of  leaves  do  not  ex- 
hale half  fo  much  as  their  under  furfaces.  He  placed  the  ftalks 
of  many  leaves  frem  collected  into  glafs-tubes  filled  with  water, 
of  many  of  thefe  the  upper  furfaces  were  fmeared  with  oil,  and 
the  under  furfaces  of  many  others  of  them  -9  and  he  uniformly 

founci 


SECT.  XXVIII.  2.  ABSORBENTS.  237 

found  by  the  finking  of  the  water  in  the  tubes,  that  the  upper 
furfaces  exhaled  lefs  by  half  than  the  under  furfaces. 

Both  the  dark- eyed  patients,  which  are  affefted  with  pulmo- 
nary ulcers  from  deficient  venous  abforption,  asdefcribed  in  Sec- 
tion XXVII.  2.  and  the  light-eyed  patients  from  deficient  lym- 
phatic abforption,  which  we  are  now  treating  of,  have  generally 
large  apertures  of  the  iris  ;  thefe  large  pupils  of  the  eyes  are  a 
common  mark  of  want  of  irritability  ;  and  it  generally  happens, 
that  an  increaie  of  fenfibility,  that  is,  of  motion?  in  confequence 
of  fenfation.  attends  thefe  conftitutions.  See  Sect.  XXXI.  2. 
Whence  inflammations  may  occur  in  thefe  from  ftagnated  fluids 
more  frequently  than  in  thofe  conftitutions,  which  poflefs  more 
irritability  and  lefs  ienfibility. 

Great  expectations  in  refpeft  to  the  cure  of  confumptions, 
as  well  as  of  many  other  difeafes,  are  produced  by  the  very  in- 
genious exertions  of  Dr.  Beddoes  ;  who  has  eftabiiftied  an  ap- 
paratus for  breathing  various  mixtures  of  airsorgafes,  at  the 
hot- wells  near  Briftol,  which  well  deferves  the  attention  of  the 
public. 

Dr  Beddoes  very  ingenioufly  concludes,  from  the  florid  col- 
our of  the  blood  of  confumptive  patients,  that  it  abounds  in  ox- 
ygene  ;  and  that  the  rednefs  of  their  tongues,  and  lips,  and  the 
fine  blufh  of  their  cheeks,  (hew  the  prefence  of  the  fame  prin- 
ciple, like  flefh  reddened  by  nitre.  And  adds,  that  the  circum- 
fiance  of  the  confumptions  of  pregnant  women  being  flopped 
in  their  progrefs  during  pregnancy,  at  which  time  their  blood 
may  be  fuppofed  to  be  in  part  deprived  of  its  oxygene,  by  ox- 
ygenating the  blood  of  the  foetus,  is  a  forcible  argument  in  fa- 
vour of  this  theory  ;  which  mud  foon  be  confirmed  or  con- 
futed by  his  experiments.  See  Efiay  on  Scurvy,  Confumption, 
&c  by  Dr  Beddoes.  Murry.  London.  Alfo  Letter  to  Dr0 
Darwin  by  the  fame.  Murry.  London. 


SFCT, 


238  RETROGRADE          SECT.  XXIX.  i.  i. 

SECT.      XXIX. 

ON   THE   RETROGRADE   MOTIONS   OF    THE   ABSORBENT  SYSTEM. 

I.  Account  of  the  abforbent  fyft em.  II.  The  valves  of  the  abforbent 
vejjels  may  fujfer  their  fluids  to  regurgitate  in  feme  difeafes.  III. 
Communication,  from  the  alimentary  canal  to  the  bladder  by  means 
of  the  abforbent  vejjels.  IV  The  phenomena  of  diabetes  explained. 
V.  i.  The  phenomena  oj  dropftes  explained.  2,  Cafes  of the  ufe 
of  foxglove.  VI,  Ofcoldfweats.  VII.  Tranjlations  of  matter  > 
of  chyle,  of  milky  of  urine ',  operation  of  purging  drugs  applied  ex- 
ternally. VIII.  Circumftances  by  which  the  fluids ,  that  are  ef- 
fufed  by  the  retrograde  motions  of  the  abforbent  veffels,  are  dijlin- 
guijhed.  IX.  Retrograde  motions  of  vegetable  juices.  X.  03- 
jeclions  anfwered.  XL  The  caufes9  which  induce  the  retrograde 
motions  of  animal  vejfils,  and  the  medicines  by  which  the  natural 
motions  are  rejlored. 

N*  B.  The  following  SecJion  is  a  tranflaticn  of  apart  of  a  Latin  the- 
Jis  written  by  the  late  Mr.  Charles  Darwin,  which  was  printed 
with  his  prize- differtation  on  a  criterion  between  matter  and  mu- 
cus in  178®.  Sold  by  Cadelly  London. 

I.  Account  of  the  Abforbent  Syjtem. 

i.  THE  abforbent  fyftem  of  veflels  in  animal  bodies  confifts 
of  feveral  branches,  differing  in  refpedl  to  their  fituations,  and 
to  the  fluids,  which  they  abforb. 

The  inteftinal  abforbents  open  their  mouths  on  the  internal 
furfaces  of  the  imeftines  ;  their  office  is  to  drink  up  the  chyle 
and  the  other  fluids  from  the  alimentary  canal ;  and  they  are 
termed  la&eals,  to  diftinguim  them  from  the  other  abforbent  vef- 
fels, which  have  been  termed  lymphatics. 

Thofe,  whofe  mouths  are  difperfed  on  the  external  fkin,  im- 
bibe a  great  quantity  of  water  from  the  atmofphere,  and  a  part 
of  the  perfpirable  matter,  which  does  not  evaporate,  and  are 
termed  cutaneous  abforbents. 

Thofe,  which  arife  from  the  internal  furface  of  the  bronchia, 
and  which  imbibe  moifture  from  the  atmofphere,  and  a  part  of 
the  bronchial  mucus,  are  called  pulmonary  abforbents. 

Thole,  which  open  their  innumerable  mouths  into  the  cells 
of  the  whole  cellular  membrane  ;  and  whofe  ufe  is  to  take  up 
the  fluid,  which  is  poured  into  thofe  cells,  after  it  has  done  its 
office  there  ;  may  be  called  cellular  abforbents. 

Thofe,  which  arife  from  the  internal  furfaces  of  the  mem- 
branes, 


SECT.  XXIX.  i.  2.  ABSORBENTS.  239 

branes,  which  line  the  larger  cavities  of  the  body,  as  the  thorax, 
abdomen,  fcrotum,  pericardium,  take  up  the  mucus  poured  in- 
to thofe  cavities  ;  and  are  diftinguifhed  by  the  names  of  their  re- 
fpe£tive  cavities. 

Whilft  thofe,  which  arife  from  the  internal  furfaces  of  the 
urinary  bladder,  gall-bladder,  falivary  du&s,  or  other  receptacles 
of  fecreted  fluids,  may  take  their  names  from  thofe  fluids  ;  the 
thinner  parts  of  which  it  is  their  office  to  abforb  :  as  urinary, 
bilious,  or  falivary  abforbents. 

2.  Many  of  thefe  abforbent  veflels,  both  la&eals  and  lymphat- 
ics, like  fome  of  the  veins,  are  replete  with  valves  :  which  feem 
defigned  to  aflift  the  progrefs  of  their  fluids,  or  at  lead  to  pre- 
vent their  regurgitation  •,  where  they  are  fubjected  to  the  inter- 
mitted  preflure  of  the   mufcular,    or  arterial  adtions  in  their 
neighbourhood. 

Thefe  valves  do  not  however  appear  to  be  neceffary  to  all  the 
abforbents,  any  more  than  to  all  the  veins  ;  fince  they  are  not 
found  to  exift  in  the  abforbent  fyftem  of  fi(h  ;  according  to  the 
difcoveries  of  the  ingenious,  and  much  lamented  Mr.  Hewfon* 
Philof.  Tranf.  v.  59,  Enquiries  into  the  Lymph.  Syft.  p.  94. 

3.  Thefe   abforbent   veflels   are  alfo  furnifhed  with  glands^ 
which  are  called  conglobate  glands  ;  whofe  ufe  is  not  at  prefent 
fufficiently  inveftigated  ;  but  it   is  probable  that  they  referable 
the  conglomerate  glands  both  in  ftru&ure  and  in  ufe,  except  that 
their  abforbent  mouths  are  for  the  conveniency  of  (ituation  plac- 
ed at  a  greater  di (lance  from  the  body  of  the  gland.     The  con- 
glomerate glands  open  their  mouths  immediately  into  the  fan- 
guiferous  veflels,  which  bring  the  blood,  from  whence  they  ab- 
forb their  refpe£tive   fluids,    quite    up  to  the  gland  ;  but  thefe 
conglobate  glands  colle£l  their  adapted  fluids  from  very  diftant 
membranes,  or   cylts,  by  means  of  mouths  furnilhed  with  long 
necks  for  this  purpofe  ;  and  which  are  called  lafteals,  or  lym- 
phatics. 

4.  The  fluids,  thus  collefted  from  various  parts  of  the  body, 
pafs  by  means  of  the  thoracic  duft  into  the  left  fubclavian  near 
the  jugular  vein  ;  except  indeed  that  thofe  collected  from  the 
right  fide  of  the  head  and  neck,  and  from  the  right  arm,  are  car- 
ried into  the   right   fubclavian  vein  :  and  fometimes  even  the 
lymphatics  from  the  right  fide  of  the    lungs  are  inferted  into 
the  right  fubclavian  vein  :     whilft  thofe  of  the  left  fide  of  the 
head  open  but  juft  into  the  fummit  of  the  thoracic  dudt. 

5.  In  the  abforbent  fyftcva  there  are  many  anaftomofes  of  the 
veiTds,  which   feem  of  great  confequence  to  the  prefervation  of 
health.     Thefe   anaitomofes  are  difcovered  by  difleftion  to  be 

very 


240  RETROGRADE          SECT.  XXIX.  i.  6. 

very  frequent  between  the  inteftinal  and  urinary  lymphatics,  as 
mentioned  by  Mr.  Hewfon,  (Phil  Tranf.  v.  58.) 

6.  Nor  do  all  the  inteftinal  abforbeflts  feem  to  terminate  in 
the  thoracic  duel,  as  appears  from  fome  curious  experiments  of 
D.  Munro,  who  gave  madder  to  fome  animals,  having  pre- 
vioufly  put  a  ligature  on  the  thoracic  duel:,  and  found  their 
bones  and  the  ferurn  of  their  blood  coloured  red. 

II.   The  Vafoes  of  tie  Abforbent  Syjtem  may  fitffer  their  Fluids  to  re- 
gurgitate in  fome  Difeajes. 

1.  THE  many  valves,  which  occur  in  the  progrefs  of  the  lym* 
phatic  and   lacteal  veflels,   would  feem  infuperable  obflacles  to 
the  regurgitation   of  their    contents.       But  as  thefe  valves  are 
placed  in  veflels,  which  are  indued  with  life,  and  are  thernfelves 
indued  with  life  alfo  ;    and  are  very  irritable  into  thofe  natural 
motions,  which  abforb,  or  propel  the  fluids  they  contain  -,  it  is 
poflible,  in  fome  difeafes,  where  thefe  valves  or  vefleis  are  ftimu- 
lated  into  unnatural  exertions,  or  are  become  paralytic,  that  dur- 
ing the  diaflole  of  the  part  of  the  veflel  to  which  the  valve  is  at- 
tached, the  valve  may  not  fo  completely  clofe,  as  to  prevent  the 
relapfe  of  the  lymph  or  chyle.     This  is  rendered  more  probable 
by  the  experiments  of  injecling  mercury,  or  water,  or  fuet,  or  by 
blowing  air  down  thefe  veflels  :    all  which  pafs  the  valves  very 
eafily,  contrary  to  the    natural  courfe  of  their  fluids,  when  the 
veflels  are  thus  a  little  forcibly  dilated,  as  mentioned  by  Dr  Hal* 
ler,  Elem.  Phyfiol.  t.  iii.  f.  4. 

"  The  valves  of  the  thoracic  duel  are  few,  fome  aflert  they 
are  not  more  than  twelve,  and  that  they  do  not  very  acurately 
perform  their  office,  as  they  do  not  clofe  the  whole  area  of  the 
duel,  and  thence  may  permit  chyle  to  repafs  them  downwards. 
In  living  animals,  however,  though  not  always,  yet  more  fre- 
quently than  in  the  dead,  they  prevent  the  chyle  from  returning. 
The  principal  of  thefe  valves  is  that,  which  prefides  over  the  in- 
fertion  of  the  thoracic  duel:,  into  the  fubclavian  vein  *,  many  have 
believed  this  alfo  to  perform  the  office  of  a  valve,  both  to  admit 
the  chyle  into  the  vein,  and  to  preclude  the  blood  from  entering 
the  duel:  •,  but  in  my  opinion  it  is  fcarcely  fufficient  for  this  pur- 
pofe."  Haller,  Elem.  Phyf.  t.  vii.  p.  226. 

2.  The  mouths  of  the  lymphatics  feem  to  admit  water  to  paf» 
through  them  after  death,  the  inverted  way,  eafier  than  the  nat- 
ural one  ;  (ince  an   inverted  bladder   readily  lets  out  the  water 
with  which  it  is  filled  ;  whence  it  may  be  inferred,  that  there  1*3 
no  obftacle  at  the  mouths  of  thefe  veflels  to  prevent  the  regurgi- 
tation of  their  contained  fluids, 

I 


SECT.  XXIX.  2.  3.       ABSORBENTS.  241 

I  was  induced  to  repeat  this  experiment,  and  having  accurate- 
ly tied  the  ureters  and  neck  of  a  frefh  ox's  bladder,  I  made  an 
opening  at  the  fundus  of  it ;  and  then,  having  turned  it  infide 
outwards,  rilled  it  half  full  with  water,  and  was  furprifed  to  fee 
it  empty  itielf  fo  haftily.  I  thought  the  experiment  more  ap- 
pofite  to  my  pur,pofe  bv  fufpending  the  bladder  with  its  neck 
downwards,  as  the  lymphatics  are  chiefly  fpread  upon  this  part 
of  it,  as  fhewn  by  Dr.  Watfon,  Philof.  Tranf  v  59  p.  392. 

3.  In  fome  difeafes,  as  in  the  diabetes,  and  fcrofuia,  it  is  prob- 
able the  valves  themfelves  are  difeafed,  and  are  thence  incapahle 
of  preventing  a  return  of  the  fluids  they  fliould  fupporr.     Thus 
the  valves  of  the  aoru  itfelf  have  frequently  i^een  found  fcirrhous, 
according  to  the  difiec~lions  of  Monf.   Lieutaud,  and  have  given 
rife  to  an  interrupted  pulfe,  and  laborious  palpitations,  by  fuffer- 
ing  a  return  of  part  of  the  blood  into  the  heart.     Nor  are  any 
parrs  of  the  body  fo  liable  to  fcirrhofity  as  the  lymphatic  glands 
and  veflels,  infomuch  that  their  fcirrhofities  have  acquired  a  dif- 
tincl:  name,  and  been  termed  fcrofuia. 

4.  There  are  valves  in  other  parts  of  the  body,  analagous  to 
thofe  of  the  abforbent  fyftem,  and  which  are  liable,  when  difeaf- 
ed,  to  regurgitate  their  contents  :  thus  the  upper  and  lower  orifi- 
ces of  the  flomach  are  clofed  by  valves,   which,  when  too  great 
quantities  of  warm  water  have  been  drunk  with  a  defign  to  pro- 
mote vomiting,  have  fometimes  re-filled  the  utmoft  efforts  of  the 
aldommal  mufcles,  and  diaphragm  ;  yet,  at  other  times,  the  up- 
per valve,  or  cardia,  eafily  permits  the  evacuation  of  the  contents 
of  the  ftomach  ;   whiHt  the  inferiour  valve,  or  pylorus,  permits 
the  bile  and  other  contents  of  the  duodenum,  to  regurgitate  into 
the  ftomach 

5.  The  valve  of  the  colon  is  well  adapted  to  prevent  the  re- 
trograde motion  of  the  excrements ;  yet,  as  this  valve  is  pofleffi. 
ed  of  a  living  power,  in  thf  iliac  paflion,  either  from  fpafm,  or 
other  unnatural  exertions,  it  keeps  itfelf  open,  and  either  fuffers 
or  promotes  the  retrograde  movements  of  the  contents  of  the 
intefUnes  below  ;  as  in  ruminating   animals  the  mouth  of  the 
firft  ftomach  feems  to  be  fo  conftrucled,  as  to  facilitate  or  aflift 
the  regurgitation  of  the  food  ;  the  rings  of  the  cefophagus  after- 
wards contrachng  themfelves  in  inverted  order      De  Haen,  by 
means  of  a  fyringe,  forced  fo  much  water  into  the  reclum  intef- 
tinum  of  a  dog,  that  he  vomited  it   in   a  full  ftream  from   his 
mouth :  and  in  the  iliac   paflion  above   mentioned,  excrements 
and   clyfter  are  often  evacuated  by  the   mouth-     See  Section 
XXV.  15. 

6    The  punc~la  lacrymalia,  with   the  lacrymal  fark  and  nafai 
duel:,  compote  a  complete  gland,  and  much  refemble  the  intek 
VOL.  I.  H  H  tinai 


242  RETROGRADE        SECT.  XXIX.  2.  7. 

tinal  canal :  the  punfta  lacrymalia  are  abforbent  mouths,  that 
take  up  the  tears  from  the  eye,  when  they  have  done  their  of- 
fice there,  and  convey  them  into  the  noftriJs  •,  but  when  the  naf- 
al  duct  is  obitru&ed,  and  the  hcrymal  fack  diftended  with  its 
fluid,  on  preflure  with  the  finger  the  mouths  of  this  gland 
(punfta  lacrymaiia)  will  readily  difgorge  the  fluid  they  had  pre- 
vioufly  abforbed,  back  into  the  eye. 

7.  As  the  capillary  velTels  receive  blood  from  the  arteries, 
and  feparating  the  mucus,  or  perfpirable  matter  from  it,  convey 
the  remainder  back  by  the  veins ;  thefe  capillary  vefTels  are  a  fet 
of  glands,  in  every  refpedl  (imilar  to  the  fecretory  vefTels  of  the 
liver,  or  other  large  congeries  of  glands.     The  beginnings    of 
thefe  capillary  veflels  have  frequent  anaftomofis  into  each  other, 
in  which  circumltance  they  are  refernbled  by  the  lafteals  :  and 
like  the  mouths  or  beginnings  of  other  glands,  they  are   a  fet 
of  abforbent  veflels,  which  drink  up  the  blood  which  is  brought 
to  them  by  the  arteries,  as  the  chyle  is  drunk  up  by  the  lacleals  : 
for  the  circulation  of  the  blood  through  the  capillaries  is  proved 
to  be  independent  of  arterial  impulfe  ;    fince  in  the  blufh   of 
fhame,  and  in  partial  inflammations,  their  a£lion  is  increafed, 
without  any  increafe  of  the  motion  of  the  heart, 

8.  Yet  not  only  the  mouths,  or  beginnings  of  thefe  anaftomo- 
fing  capillaries  are  frequently  feen  by  microfcopes,  to  regurgitate 
fome  particles  of  blood,  during  the  ftruggles  of  the  animal ;  but 
retrograde  motion  of  the  blood,  in  the  veins  of  thofe  animals, 
from  the  very  heart  to  the  extremity  of  the  limbs,  is  obfervable, 
by  intervals,  during  the  diftrefies  of  the  dying  creature.     Haller, 
Elem.  Phyfiol.  t.  i.  p.  216.     Now,    as  the  veins  have  perhaps 
all  of  them  a  valve  fomewhere  between  their  extremities  and 
the  heart,  here  is  ocular  demonftration  of  the  fluids  in  this  difeaf- 
ed  condition  of  the  animal,  repafling  through  venous  valves : 
and  it  is  hence  highly  probable,  from  the  ftrideft  analogy,  that 
if  the  courfe  of  the  fluids,  in  the  lymphatic  veflels,  could  be  fub- 
jefled  to  microfcopic  obfervation,  they  would  alfo  in  the  difeaf- 
ed  ftate  of  the  animal,  be  feen    to  repafs  the  valves,  and  the 
mouths  of  thofe  veflels,  which  had  previoufly  abforbed  them,  or 
promoted  their  progrefllon, 

Mr.  Cooper  relates  fome  curious  inftances  of  difeafed  valves 
of  the  abforbent  fyftem,  and  found  on  difleding  dogs,  who  had 
died  fome  hours  after  he  had  put  a  ligature  on  the  receptaculum 
chyli,  that  in  the  cellular  membrane  of  thofe  dogs,  which  had 
their  ftomachs  full  previous  to  the  application  of  the  ligature, 
much  chyle  was  efFufed  on  many  of  the  vifcera,  and  into  the 
cellular  membrane  connecting  the  laminae  of  the  mefentery, 
and  on  the  anterior  furfaces  of  the  pancreas,  and  of  the  kidneys  \ 

part 


SECT.  XXIX.  3.  i.         ABSORBENTS.     .  243 

part  of  which  might  have  efcaped  from  a  rupture  of  the  recep- 
taculum  chyli ;  yet  other  parts  of  this  general  erFufion  of  chyle 
mull  feem  to  have  been  occafioned  by  their  retrograde  action 
in  the  dying  date  of  the  animals.  Medical  Refearches,  p.  106. 
There  is  a  curious  cafe  of  ifchuria  related  by  Dr,  J,  Senter, 
in  the  Tranfaaions  of  the  College  of  Philadelphia,  Vol.  I.  1793* 
which  continued  more  than  three  years,  during  which  time,  if 
the  urine  was  not  drawn  off  by  a  catheter,  it  was  frequently  void- 
ed by  vomiting,  and  fometimes  by  the  (kin;  which  could  not 
be  accounted  for,  as  Dr.  Senter  jultly  obferves,  but  by  toppof- 
ing  the  exigence  of  the  retrograde  adion  of  fome  parts  of  the 
lymphatic  fyftem. 

III.    Communication  from  the  Alimentary   Canal  to  the  Bladder,  by 
means  of  the  Abforbent  Veffels. 

MANY  medical  philofophers,both  ancient  and  modern,have  fuf- 
pecled  that  there  was  a  nearer  communication  between  the  flom- 
ach  and  the  urinary  bladder,  than  that  of  the  circulation  :  they 
were  led  into  this  opinion  from  the  great  expedition  with  which 
cold  water,  when  drunk  to  excefs,  pafies  off  by  the  bladder  \ 
and  from  the  fimilarity  of  the  urine,  when  produced  in  this  haft  y 
manner,  with  the  material  that  was  drunk. 

The  :ormer  of  thefe  circumftances  happens  perpetually  to 
thofe  who  drink  abundance  of  cold  water,  when  they  are  much 
headed  by  exercife,  and  to  many  at  the  beginning  of  intoxication. 

Of  the  latter,  many  inftances  are  recorded  by  Etmuller,  t.  xi. 
p.  716.  where  firnple  water,  wine,  and  wine  with  fugar,  and 
emulfions,  were  returned  by  urine  unchanged. 

There  are  other  experiments,  that  feem  to  demonflate  the 
exiftence  of  another  pafTage  to  the  bladder,  befides  that  through 
the  kidneys.  Thus  Dr.  Kratzenftein  put  ligatures  on  the  ure- 
ters of  a  dog  and  then  emptied  the  bladder  by  a  catheter  ;  yet 
in  a  little  time  the  dog  drank  greedily,  and  made  a  quantity  of 
water,  (Difputat.  Morbor.  Halleri.  t.  iv.  p.  63.)  A  fimilar  ex- 
periment is  related  in  the  Philofophical  Tranfadlions,  with  the 
lame  event,  (No.  65,  67,  for  the  year  1670.) 

Add  to  this,  that  in  fome  morbid  cafes  the  urine  has  continu- 
ed to  pafs,  after  the  fuppuration  or  total  definition  of  the  kid- 
neys;  of  which  many  inftances  are  referred  to  in  the  Elem. 
Phyfiol.  t.  vii.  p.  379.  of  Dr.  Haller. 

From  all  which  it  muft  be  concluded,  that  fome  fluids  Lav* 
pafled  from  the  ftomach  or  abdomen,  without  having  gone 
through  the  fanguiferous  circulation  :  and  as  the  bladder  is  top- 
plied  with  many  lymphatics,  as  defcribed  by  Dr.  Watfon,  in  the 

Philof. 


244  RETROGRADE         SECT.  XXIX.  3.  i. 

Philof.  Tranf.  v.  59.  p.  392.  and  as  no  other  veflels  open  into  it  be^ 
fides  thefc  and  the  ureters,  it  feems  evident,  that  the  unnatural 
urine,  produced  as  above  defcribed,  when  the  ureters  were  tied,or 
the  kidneys  obliterated,  was  carried  into  the  bladder  by  the  retro- 
grade motions  of  the  urinary  branch  of  the  lymphatic  fyftem. 

The  more  certainly  jroafcertam  the  exiftenceof  another  commu- 
nication between  the  ftomach  and  bladder  befides  that  of  the  cir- 
culation,the  following  experiment  was  made,  to  which  I  mud  beg 
your  patient  attention  : — A  friend  of  mine  (June  14,  1772)  on 
drinking  repeatedly  of  cold  fmall  punch,  till  he  began  to  be  intox- 
icated, made  a  quantity  of  colourlefs  urine.  He  then  drank  about 
two  drams  of  nitre  difTolved  in  fome  of  the  punch,  and  ate  about 
twenty  ilalks  of  boiled  afparagus  ;  on  continuing  to  drink  more 
of  the  punch,  the  next  urine  that  he  made  was  quite  clear,  and 
without  fmell  :  but  in  a  little  time  another  quantity  was  made, 
which  was  not  quite  fo  colourlefs,  and  had  a  ftrong  fmell  of  the 
afparagus  :  he  then  loft  about  four  ounces  of  blood  from  the  arm. 

The  fmell  of  afparagus  was  not  at  all  perceptible  in  the  blood, 
neither  when  frefh  taken,  nor  the  next  morning,  as  myfelf  and 
two  others  accurately  attended  to  ;  yet  this  fmell  was  itrongly 
perceived  in  the  urine,  which  was  made  juft  before  the  blood 
was  taken  from  his  arm. 

Some  bibulous  paper,  moiftened  in  the  ferum  of  this  blood, 
and  differed  to  dry,  (hewed  no  figns  of  nitre  by  its  manner  of 
burning.  But  fome  of  the  fame  paper  moiftened  in  the  urine, 
and  dried,  on  being  ignited,  evidently  (hewed  the  prefence  of  ni- 
tre. This  blood  and  the  urine  flood  fome  days  expofed  to  the 
fun  in  the  open  air,  till  they  were  evaporated  to  about  a  fourth  of 
their  original  quantity,  and  began  to  (link  :  the  paper,  which 
was  then  moiftened  with  the  concentrated  urine,  (hewed  the 
prefence  of  much  nitre  by  its  manner  of  burning  ;  whilft  that 
moiftened  with  the  blood  (hewed  no  fuch  appearance  at  all. 

Hence  it  appears  that  certain  fluids  at  the  beginning  of  in- 
toxication, find  another  paflage  to  the  bladder  befides  the  long 
courfe  of  the  arterial  circulation  ;  and  as  the  inteftinal  abforb- 
ents  are  joined  with  the  urinary  lymphatics  by  frequent  anafto- 
mofes,  as  Hewfon  has  demonftrated  ;  and  as  there  is  no  other 
road,  we  may  juftly  conclude,  that  thefe  fluids  pafs  into  the  blad- 
der by  the  urinary  branch  of  the  lymphatics  which  has  its  mo- 
tions inverted  during  the  difeafed  (late  of  the  animal. 

A  gentleman  who  had  been  fome  weeks  affecled  with  jaun- 
dice, and  whofe  urine  was  in  confequence  of  a  very  deep  yellow, 
took  fome  cold  fmall  punch,  in  which  was  diffblved  about  a 
dram  of  nitre  ;  he  then  took  repeated  draughts  of  the  punch, 
and  kept  himfelf  in  a  cool  room,  till  on  the  approach  of  flight 

intoxication 


SECT.  XXIX.  4.  i.         .  ABSORBENTS-  245 

Intoxication  he  made  a  large  quantity  of  water  5  this  water  had  a. 
flight  yellow  tinge,  as  might  be  expected  iron  a  fm  all  admix- 
ture of  bile  fecreted  from  the  kidneys  ;  but  if  the  whole  of  it 
had  pafled  through  the  fanguiferous  veflels,  which  were  now  re- 
plete with  bile  (his  whole  (kin  being  as  yellow  as  gold)  would 
not  this  urine  alfo,  as  well  as  that  he  had  made  for  weeks  be- 
fore, have  been  of  a  deep  yellow  ?  Paper  dipped  in  this  water, 
and  dried,  and  ignited,  {hewed  evident  marks  of  the  prefence  of 
nitre,  when  the  flame  was  blown  out. 

IV.   The  Phenomena  of  the  Diabetes  explained,  and  of  feme  Diar- 
rhoeas. 

THE  phenomena  of  many  difeafes  are  only  explicable  from 
the  retrograde  motions  of  fome  of  the  branches  of  the  lymphat- 
ic fyftem;  as  the  great  and  immediatte  flow  of  pale  urine  in  the 
beginning  of  drunkennefs  ;  in  hyfteric  paroxyfms ;  from  being 
cxpofed  to  cold  air  ;  or  to  the  influence  of  fear  or  anxiety. 

Before  we  endeavour  to  illuftrate  this  do6lrine,  by  defcribing 
the  phenomena  of  thefe  difeafes,  we  muft  premife  one  circum- 
flance  ;  that  all  the  branches  of  the  lymphatic  fyftem  have  a  cer- 
tain fympathy  with  each  other,  inibmuch  that  when  one  branch 
is  ftimulated  into  unufual  kinds  or  quantities  of  motion,  fome 
other  branch  has  its  motions  either  increafed,  or  decreafed,  or 
inverted  at  the  fame  time.  This  kind  of  fympathy  can  only  be 
proved  by  the  concurrent  teftimony  of  numerous  facts,  which 
will  be  related  in  the  courfe  of  the  work.  I  (hall  only  add  here, 
that  it  is  probable,  that  this  fympathy  does  not  depend  on  any 
communication  of  nervous  filaments,  but  on  habit  j  owing  to 
the  various  branches  of  this  fyftem  having  frequently  been  ftim- 
ulated  into  action  at  the  fame  time, 

There  are  a  thoufand  inftances  of  involuntary  motions  aflbci- 
ated  in  this  manner  ;  as  in  the  aft  of  vomiting,  while  the  mo- 
tions of  the  ftomach  and  cefopha^-us  are  inverted,  the  pulfations 
of  the  arterial  fyftem  by  a  certain  fympathy  become  weaker ;  and 
when  the  bowels  or  kidneys  are  ftimulated  by  poifon,  a  ftone,  or 
inflammation,  into  more  violent  action  ;  the  ftomach  and  cefoph- 
agus  by  fympathy  invert  their  motions. 

i .  When  any  one  drinks  a  moderate  quantity  of  vinous  fpir- 
it,  the  whole  fyftem  acts  with  more  energy  by  confent  with  the 
ftomach  and  inteftines,  as  is  feen  from  the  glow  on  the  (kin,  and 
the  increafe  of  ftrength  and  activity  ;  but  when  a  greater  quan- 
tity of  this  inebriating  material  is  drunkj  at  the  fame  time  that 
the  ladleals  are  excited  into  greater  action  to  abforb  it  ;  it  fre- 
quently happens,  that  the  urinary  branch  of  abforbents,  which  is 

connected 


246  RETROGRADE          SECT.  XXIX.  4.  2. 

conne£led  with  the  ladleals  by  many  anaftomofes,  inverts  its  mo- 
tions, and  a  great  quantity  of  pale  unanimalized  urine  is  dif- 
charged.  By  this  wife  contrivance  too  much  of  an  unneceflary 
fluid  is  prevented  from  entering  the  circulation — This  may  be 
called  the  drunken  diabetes,  to  diftinguifh  it  from  the  other  tem- 
porary diabetes,  which  occur  in  hyfleric  difeafes,  and  from  con- 
tinued fear  or  anxiety. 

2,  If  this  idle  ingurgitation  of  too  much  vinous  fpirit  be  dai- 
ly praftifed,  the  urinary  branch  of  abforbents  at  length  gains  a 
habit  of  inverting  its  motions,  whenever  the  la&eals  are  much 
flimulated  ;  and  the  whole  or  a  great  part  of  the  chyle  is  thus 
daily  carried  to  the  bladder  without  entering  the  circulation,  and 
the  body  becomes  emaciated.  This  is  one  kind  of  chronic  dia- 
betes, and  may  be  diftinguifhed  from  the  others  by  the  tafte  and 
appearance  of  the  urine  ;  which  is  fweet,  and  of  the  colour  of 
whey,  and  may  be  termed  the  chyliferous  diabetes. 

5.  Many  children  have  a  fimilar  depofition  of  chyle  in  their 
urine,  from  the  irritation  of  worms  in  their  inteftines,  which 
ftimulating  the  mouths  of  the  la&eals  into  unnatural  a£Uon,the 
urinary  branch  of  the  abforbents  becomes  inverted,  and  carries 
part  of  the  chyle  to  the  bladder:  part  of  tbe  chyle  alfo  has  been 
carried  to  the  iliac  and  lumber  glands,  of  which  inftances  are 
recorded  by  Halleiyt.  vii,  225.  and  which  can  be  explained  on 
no  other  theory,:  but  the  difTe£lions  of  the  lymphatic  fyftem  of 
the  human  body,  which  have  yet  been  publifhed,  are  not  fuffi- 
ciently  extenfive  for  our  purpofe  ;  yet  if  we  may  reafon  from 
comparative  anatomy,  this  tranilation  of  chyle  to  the  bladder  is 
much  illuftrated  by  the  account  given  of  this  fyftem  of  veflels  in 
a  turtle,  by  Mr.  Hewfon,  who  obferved,  "  That  the  lafteals  near 
the  root  of  the  mefentery  anaftomofe,  fo  as  to  form  a  net- work, 
from  which  feveral  large  branches  go  into  fome  confiderable 
lymphatics  lying  near  the  fpine  ;  and  which  can  be  traced  al- 
moft  to  the  anus,  and  particularly  to  the  kidneys.  Philof. 
Tranf.  v.  59.  p.  199 — Enquiries,  p.  74. 

4.  At  the  fame  time  that  the  urinary  branch  of  abforbents,  in 
the  beginning  of  diabetes,  is  excited  into  inverted  adion,  the 
cellular  branch  is  excited  by  the  fympathy  above  mentioned,  in- 
to more  energetic  atHon  ;  and  the  fat,  that  was  before  depofited, 
is  reabforbed  and  thrown  into  the  blood  veflels;  where  it  floats  5 
and  was  miftaken  for  chyle,  till  the  late  experiments  of  the  inge- 
nious Mr.  Hewfon  demonftrated  it  to  be  fat. 

This  appearance  of  what  was  miftaken  for  chyle  in  the  blood, 
which  was  drawn  from  thefe  patients,  and  the  obftrudled  liver, 
which  very  frequently  accompanies  this  difeafe,  feems  to  have 
led  Dr.  Mead  to  fufpeft  the  diabetes  was  owing  to  a  defeft  of 

fanguification  » 


SECT.  XXIX.  4- 5-       ABSORBENTS.  247 

fanguification  ;  and  that  the  fcirrhofity  of  the  liver  was  the  orig- 
inal caufe  of  it  :  but  as  the  icirrhus  of  the  liver  is  mod  frequent- 
ly owing  to  the  fame  caufes,  that  produce  the  diabetes  and  drop- 
(ies  ;  namely,  the  great  ufe  of  fermented  liquors  ;  there  is  no 
wonder  they  fhould  exift  together,  without  being  the  confe- 
quence  of  each  other. 

5.  If  the  cutaneous  branch  of  abforbents  gains  a  habit  of  being 
excited  into  ftronger  adtion,  and  imbibes  greater  quantities  of 
moifture  from  the  atmofphere,  at  the  fame  time  that  the  urina- 
ry branch  has  its  motions  inverted,  another  kind  of  diabetes  is 
formed,  which  may  be  termed  the  aqueous  diabetes.  In  this 
diabetes  the  cutaneous  abforbents  frequently  imbibe  an  amazing 
quantity  of  atmofpheric  moifture  ;  infomuch  that  there  are  au- 
thentic hiftories,  where  many  gallon*  a  day,  for  many  weeks  to- 
gether, above  the  quantity  that  has  been  drunk,  have  been  dif- 
charged  by  urine. 

Dr.  Keil,  in  his  Medicina  Statica,  found  that  he  gained  eigh- 
teen ounces  from  the  moid  air  of  one  night ;  and  Dr.  Percivai 
affirms,  that  one  of  his  hands  imbibed,  after  being  well  chafed, 
near  an  ounce  and  half  of  water,  in  a  quarter  of  an  hour. 
(Tranfaft.  of  the  College,  London,  vol.  ii.  p.  102.)  Home's 
Medic.  Faas,p.  2.  feel.  3. 

Dr.  Rollo  in  his  work  on  Diabetes  has  fhewn,  that  one  patient, 
whom  he  weighed  after  being  ten  minutes  in  the  warm  bath, 
did  not  weigh  heavier  on  his  leaving  it.  Dr.  Currie,  I  think, 
mentions  a  fimilar  faft.  I  fufpedl,  that  if  the  bath  be  made  very 
hot,  perhaps  much  above  animal  heat,  the  bather  may  perfpire 
more  than  he  abforbs,  and  become  in  reality  lighter.  And  that 
in  a  more  moderate  heat,  if  the  patient  has  been  previoufly  ex- 
haufted  by  abilinenceor  fatigue,  that  he  will  abforb  much;  but 
that  if  his  fyftem  be  already  full  of  fluids,  from  the  food  and  flu- 
ids, which  he  has  previoufly  eaten  and  drunk,  he  may  not  abforb 
any  thing.  See  Clafs  I.  3.  2.  6. 

The  pale  urine  in  hyfterical  women,  or  which  is  produced  by 
fear  or  Anxiety,  is  a  temporary  complaint  of  this  kind  ;  and  it 
would  in  reality  be  the  fame  difeafe,  if  it  was  confirmed  by  habit. 

6.  The  purging  {tools,  and  pale  urine,  occafioned  by  expofing 
the  naked  body  to  cold  air,  or  fprinkling  it  with  cold  water,  orig- 
inate from  a  flmilar  caufe  ;  for  the  mouths  of  the  cutaneous 
lymphatics  being  fuddenly  expofed  to  cold  become  torpid,  and 
ceafe,  or  nearly  ceafe,  to  ad:  ;  whilft,  by  the  fympathy  above  de- 
fcribed,  not  only  the  lymphatics  of  the  bladder  and  inteftines 
ceafe  alfo  to  abforb  the  more  aqueous  and  faline  part  of  the  flu- 
ids fecreted  into  them  ;  but  it  is  probable  that  thefe  lymphatics 
invert  their  motions,  and  return  the  fluids,  which  were  previ- 

ouflv 


348  RETROGRADE     SECT.  XXIX.  4.  7, 

oufly  abforbed,  into  the  inteftines  and  bladder.  At  the  very 
inftant  that  the  body  is  expofed  naked  to  the  cold  air,  an  unu- 
fual  movement  is  felt  in  the  bowels  ;  as  is  experienced  by  boys 
going  into  the  cold  bath  :  this  could  not  occur  from  an  obftruc- 
tion  of  the  perfpirable  matter,  fince  there  is  not  time  for  that 
to  be  returned  to  the  bowels  by  the  courfe  of  the  circulation. 

There  is  alfo  a  chronic  aqueous  diarrhoea,  in  which  the  atmof- 
pheric  moifture,  drunk  up  by  the  cutaneous  and  pulmonary  lym- 
phatics, is  poured  into  the  inteftines,  by  the  retrograde  motions 
of  the  lafteals.  This  difeafe  is  moft  fimilar  to  the  aqueous  di- 
abetes, and  is  frequently  exchanged  for  it  :  a  diftincl  inftance 
of  this  is  recorded  by  Benningerus,  Cent,  v  Obf  98.  in  which 
an  aqueous  diarrhoea  fucceeded  an  aqueous  diabetes,  and  deftroy- 
ed  the  patient.  There  is  a  curious  example  of  this,  defcribed  by 
Sympfon  (De  Re  Medica) — "  A  young  man  (fays  he)  wasfeiz- 
ed  with  a  fever,  upon  which  a  diarrhoea  came  on,  with  great 
ftupor  ;  and  he  refufed  to  drink  any  thing,  though  he  was 
parched  up  with  exceffive  heat  :  the  better  to  fupply  him 
with  moifture,  I  dire&ed  his  feet  to  be  immerfed  in  cold  warer ; 
immediately  I  obferved  a  wonderful  decreafe  of  water  in  the  vef- 
fel,  and  then  an  impetuous  ftream  of  a  fluid,  fcarcely  coloured, 
was  difchargecl  by  ftool,  like  a  cataraft." 

7.  There  is  another  kind  of  diarrhoea,  which  has  been   called 
cseliaca  ;  in  this  difeafe  the  chyle,  drunk  up    by  the   laftealsof 
the  fmall  inteftines,  is  probably  poured  into  the  large  inteftines 
by  the  retrograde  motions  of  their  lafteals  :  as  in  the  chyliferous 
diabetes,  the  chyle  is  poured  into  the  bladder,  by  the  retrograde 
motions  of  the  urinary  branch  of  abforbents. 

The  chyliferous  diabetes,  like  this  chyliferous  diarrhoea,  pro- 
duces fudden  atrophy  ;  fince  the  nourUhment,  which  ought  to 
fupply  the  hourly  wafte  of  the  body,  is  expelled  by  the  bladder, 
or  redlum  :  whilft  the  aqueous  diabetes,  and  the  aqueous  diar- 
rhoea produce  exceffive  thirft  ,  becaufe  the  moifture,  which  is 
obtained  from  the  atmofphere,  is  not  conveyed  to  the  thoracic 
receptable,  as  it  ought  to  be,  but  to  the  bladder,  or  lower  intef- 
tines ;  whence  the  chyle,  blood,  and  whole  fyftem  of  glands,  are 
robbed  of  their  proportion  of  humidity. 

8.  There  is  a  third  fpecies  of  diabetes,  in  which  the  urine  is 
mucilaginous,   and  appears  ropy   in  pouring  it  from  one  veflel 
into  another  •,   and  will  fometimes  coagulate  over  the  fire.      This 
difeafe  appears  by  intervals,  and  ceafes  again,  and  feems  to  be 
occafioned  by  a    previous   dropfy  in  fome  part   of   the    body, 
When  fuch  a  collection   is  reabforbed,  it  is  not  always  returned 
into  the  circulation  ;  but  the  fame  irritation  that  ftimulates  one 
lymphatic  branch  to  reabforb  the  depofited    fluid,  inverts  the 

urinarv 


SECT.  XXIX.  4. 9.        ABSORBENTS.  249 

urinary  branch,  and  pours  it  into  the  bladder.  Hence  this  mu- 
cilaginous diabetes  is  a  cure,  or  the  confequence  of  a  cure,  of  a 
worfe  difeafe,  rather  than  a  difeafe  itfelf. 

Dr.  Cotunnius  gave  half  an  ounce  of  cream  of  tartar,  every 
morning,  to  a  patient,  who  had  the  anafarca  ;  and  he  voided  a 
great  quantity  of  urine  ;  a  part  of  which,  put  over  the  fire,  co- 
agulated, on  the  evaporation  of  half  of  it,  fo  as  to  look  like  the 
white  of  an  egg-  De  Ifchiade  Nervos. 

This  kind  of  diabetes  frequently  precedes  a  dropfy,  and  has 
this  remarkable  circumflance  attending  it,  that  it  generally  hap- 
pens in  the  night;  as  during  the  recumbent  (late  of  the  body, 
the  fluid,  thar  was  accumulated  in  the  cellular  membrane,  or  in 
the  lungs,  is  more  readily  abforbed,  as  it  is  lefs  impeded  by  its 
gravity.  I  have  feen  more  than  one  inftance  of  this  difeafe. 
Mr.  D.  a  man  in  the  decline  of  life,  who  had  long  accuftomed 
himfelf  to  fpirituous  liquor,  had  fwelled  legs,  and  other  fymp- 
toms  of  approaching  anafarca  ;  about  once  in  a  week  or  ten  days, 
for  tevcral  months,  he  was  feized,  on  going  to  bed,  with  great 
general  uneaHnefs,  which  his  attendants  refembled  to  an  hyfteric 
fit  ;  and  which  terminated  in  a  great  difcharge  of  vifcid  urine  5 
his  legs  became  lefs  fwelled,  and  he  continued  in  better  health 
for  fome  days  afterwards.  I  had  not  the  opportunity  to  try  if 
this  urine  would  coagulate  over  the  fire,  when  part  of  it  was 
evaporated,  which  I  imagine  would  be  the  criterion  of  this  kind 
of  diabetes  ;  as  the  mucilaginous  fluid  depofited  in  the  cells  and 
cyds  of  the  body,  which  h  tve  no  communication  with  the  exter- 
nal air,  feems  to  acquire,  by  ilagnation,  this  property  of  coagula- 
tion by  heat,  which  the  fecreted  mucus  of  the  inteltines  and  blad- 
der do  not  appear  to  poffrfs ;  as  I  have  found  by  experiment : 
and  if  any  one  fhou'd  fuppofe  this  coaguiable  urine  was  fepa- 
rated  from  the  blood  by  the  kidneys,  he  may  recollecT;  that  in  the 
mod  inflammatory  diieafes,  in  which  the  blood  is  moil  replete 
or  moil  ready  to  part  with  the  coaguiable  lymph,  none  of  this 
appears  in  the  urine. 

9.  Different  kinds  of  diabetes  require  different  methods  of 
cure.  For  the  firft  kind,  chyliferous  diabetes,  after  clearing 
the  ftomach  and  inteftines,  by  ipecacuanha  and  rhubarb,  to 
evacu-ite  any  acid  material,  which  may  too  powerfully  ftimulate 
the  mouths  of  the  lacleals,  repeated  and  large  dofes  of  tincture 
of  cantharides  have  been  much  recommended.  The  fpecific 
flimulus  of  this  medicine,  on  the  neck  of  the  bladder,  is  likely 
to  excite  the  numerous  abiorbent  veilels,  which  are  fpread  on 
that  part,  into  flronger  natural  adlioiis,  and  by  that  means  pre- 
vent their  retrograde  ones;  till,  by  perfiiting  in  the  ufe  of  the 
medicine,  their  natural  habits  of  motions  might  again  be.  eftab- 
VOL,  I.  I  i  lifted. 


250  RETROGRADE        SECT.  XXIX.  4. 9. 

lifted.  Another  indication  of  cure,  requires  fuch  medicines,  as  by 
lining  the  inteftines  with  mucilaginous  fubftances  or  with  fuch  as 
coniift  of  ihiooth  particles,  or  which  chemically  deftroy  the  acri- 
mony of  their  contents,  may  prevent  the  too  great  action  of  the 
inteilinal  abforbents.  For  this  purpofe  I  have  found  the  earth 
precipitated  from  a  folutioi>of  alum,  by  means  of  fixed  alkali,  giv- 
en in  the  dofe  of  half  a  dram  every  fix  hours,  of  great  advantage, 
with  a  few  grains  of  rhubarb,  fo  as  to  produce  a  daily  evacuation. 

The  food  mould  confiil  of  materials  that  have  the  lead  ftim- 
ulus,  with  calcareous  water,  as  of  Briftol  and  Matlock  ;  that  the 
mouths  of  the  lacleals  may  be  as  little  ftimulated  as  is  neceflary 
for  their  proper  abforption  ;  left  with  their  greater  exertions, 
ihould  be  connected  by  fympathy,  the  inverted  motions  of  the 
urinary  lymphatics. 

The  fame  method  may  be  employed  with  equal  advantage  in 
the  aqueous  diabetes,  fo  great  is  the  fympathy  between  the  (kin 
and  the  (tomach.  To  which,  however,  fome  application  to  the 
ikin  might  be  ufefully  added  ;  as  rubbing  the  patient  all  over 
with  oil,  to  prevent  the  too  great  action  of  the  cutaneous  abforb- 
ents. I  knew  an  experiment  of  this  kind  made  upon  one  pa- 
tient with  apparent  advantage. 

The  mucilaginous  diabetes  will  require  the  fame  treatment, 
which  is  moil  efficacious  in  the  dropfy,  and  will  be  defcribed  be- 
low. I  mult  add,  that  the  diet  and  medicines  above  mentioned, 
are  ilrongly  recommended  by  various  authors,  as  by  Morgan, 
Willis,  Harris,  and  Etmuller  •,  but  more  hiftories  of  the  fuccefs- 
ful  treatment  of  thefe  difeafes  are  wanting  to  fully  afcertain  the 
mod  efficacious  methods  of  cure. 

In  a  letter  from  Mr.  Charles  Darwin,  dated  April  24,  1778, 
Edinburgh,  is  the  fubfequent  paffage  : — "  A  man  who  had  long 
laboured  under  a  diabetes,  died  yefterday  in  the  clinical  ward. 
He  had  for  fome  time  drunk  four,  and  pafled  twelve  pounds  of 
fluid  daily  j  each  pound  of  urine  contained  an  ounce  of  fugar. 
He  took,  without  confiderable  relief,  gum  kino,  fanguis  draconis 
melted  wifh  alum,  tincture  of  cantharides,  ifinglafs,  gum  arabic, 
crab's  eyes,  fpirit  of  hartflhorn,  and  eat  ten  or  fifteen  oyfters 
thrice  a  day.  Dr.  Home,  having  read  my  thefis,  bled  him,  and 
found  that  neither  the  frefh  blood  nor  the  ferum  tailed  fweet. 
His  body  was  opened  this  morning — every  vifcus  appeared  in  a 
found  and  natural  (late,  except  that  the  left  kidney  had  a  very 
fmall  pelvis,  and  that  there  was  a  confiderable  enlargement  of 
mod  of  the  mefenteric  lymphatic  glands.  I  intend  to  infert  this 
in  my  thefis,  as  it  coincides  with  the  experiment,  where  fome 
afparagus  was  eaten  at  the  beginning  of  intoxication,  and  its 
fmell  perceived  in  the  urine,  though  not  in  the  blood." 

The 


SECT.  XXIX.  4.  9.      ABSORBENTS.  25 1 

The  following  cafe  of  chyliferous  diabetes  is  extracted  from 
fome  letters  of  Mr.  Hughes,  to  whofe  unremitted  care  the  in- 
firmary at  Stafford  for  many  years  was  much  indebted.  Dated 
O&ober  10,  1778. 

Richard  Davis,  aged  33,  a  whitefmith  by  trade,  had  drunk 
hard  by  intervals  j  was  much  troubled  with  fweating  of  his  hands, 
which  incommoded  him  in  his  occupation,  but  which  ceafed  on 
his  frequently  dipping  them  in  lime.  About  ieven  months  ago 
he  began  to  make  large  quantities  of  water ;  his  legs  are  oedein- 
atous,  his  belly  tenfe,  and  he  complains  of  a  rifing  in  his  throat, 
like  the  globus  hyftericus  ;  he  eats  twice  as  much  as  other  peo- 
ple, drinks  about  fourteen  pints  of  fmall  beer  a  day,  be  fides  a 
pint  of  ale,  fome  milk-porridge,  and  a  bafon  of  broth,  and  he 
makes  about  eighteen  pints  of  water  a  day. 

He  tried  alum,  dragon's  blood,  fteel,  blue  vitriol,  and  canthar- 
ides  in  large  quantities,  and  duly  repeated,  under  the  care  of 
Dr.  Underbill,  but  without  any  effect  ;  except  that  on  the  day 
after  he  omitted  the  cantharides,  he  made  but  twelve  pints  of 
water,  but  on  the  next  day  this  good  effecT:  ceafed  again. 

November  21. — He  made  eighteen  pints  of  water,  and  he 
now,  at  Dr.  Darwin's  requeft,  tooJc  a  grain  of  opium  every  four 
hours,  and  five  grains  of  aloes  at  night ;  and  had  a  flannel  fhirt 
given  him. 

22. — Made  fixteen  pints.     23. — Thirteen  pints:  drinks  lefs. 

24. — Increafed  the  opium  to  a  grain  and  a  quarter  every  four 
hours  :  he  made  twelve  pints. 

25. — Increafed  the  opium  to  a  grain  and  half:  he  now  makes 
ten  pints,  and  drinks  eight  pints  in  a  day. 

The  opium  was  gradually  increafed  during  the  next  fortnight, 
till  he  took  three  grains  ever  four  hours,  but  without  any  fur- 
ther dimunition  of  his  water.  During  the  ufe  of  the  opium  he 
fvveat  much  in  the  nights,  fo  as  to  have  large  drops  (land  on  his 
face  and  all  over  him.  The  quantity  of  opium  was  then  gradu*- 
ally  decreated,  but  not  totally  omitted,  as  he  continued  to  take 
about  a  grain  morning  and  evening. 

January  17. — He  makes  fourteen  pints  of  water  a  day.  Dr. 
Underhill  now  dire&ed  him  two  fcruples  of  common  re  fin  tritu- 
rated with  as  much  fugar,  every  fix  hours ;  and  three  grains  of 
opium  every  night. 

19. — Makes  fifteen  pints  of  water;  fweats  at  night. 

2i. — Makes  feventeen  pints  of  water  ;  has  twitchings  of  his 
limbs  in  a  morning,  and  pains  of  his  legs  :  he  now  takes  a  dram 
of  refm  for  a  dofe  and  continues  the  opium. 

23. — Water  more  coloured,  and  reduced  to  fixteen  pints,  and 
he  thinks  has  a  brackiih  tafle. 

26. — Water 


252  RETROGRADE         SECT.  XXIX.  4.  9. 

26. — Water  reduced  to  fourteen  pints. 

28. — Water  thirteen  pints  :  he  continues  the  opium,,  and 
takes  four  fcruples  of  the  refin  for  a  dofe. 

February  i. — Water  twelve  pints. 

4. — Water  eleven  pints  :  twitchings  lefs  ;  takes  five  fcruples 
for  a  dofe. 

8. — Water  ten  pints  :  has  had  many  (lools. 

12- — Appetite  lefs:  purges  very  much. 

After  this  the  refin  either  purged  him,  or  would  not  flay  on 
his  fiomach :  and  he  gradually  relapfed  nearly  to  his  former 
condition,  and  in  a  few  months  funk  under  the  diieafe. 

Odober  3,  Mr.  Hughes  evaporated  two  quarts  of  the  water, 
and  obtained  from  it  four  ounces  and  half  of  hard  and  brittle 
faccharine  mafs,  like  treacle  which  had  been  fometime  boiled. 
Four  ounces  of  blood  which  he  took  from  his  arm  with  defign  to 
examine  it,  had  the  common  appearances,  except  that  the  fe- 
rum  refembled  cheefe-whey  ;  and  that  on  the  evidence  of  four 
perfons,  two  of  whom  did  not  know  what  it  was  they  tafted,  the 

ferum  had  a  faltifb  tfifte. 
j  j     j      */ 

From  hence  it  appears,  that  the  faccharine  matter,  with  which 
the  urine  of  thefe  patients  fo  much  abounds  does  not  enter  the 
blood-veflels  like  the  nitre  and  afparagus  mentioned  above  ;  but 
that  the  procefs  of  digeftion  refembles  the  procefs  of  the  ger- 
mination of  vegetables,  or  of  making  barley  into  malt  ;  as  the 
valt  quantity  of  fugar  found  in  the  urine  muft  be  made  from 
the  food  which  he  took  (which  was  double  that  taken  by  others), 
and  from  the  fourteen  pints  of  fmall  beer  which  he  drank.  And, 
fecondly,  as  the  ferum  of  the  blood  was  not  fweet,  the  chyle  ap- 
pears to  have  been  conveyed  to  the  bladder  without  entering  the 
circulation  of  the  blood,  fince  fo  large  a  quantity  of  fugar,  as 
was  found  in  the  urine,  namely  twenty  ounces  a  day,  could  not 
have  previoufly  exifled  in  the  blood  without  being  perceptible  to 
the  taite. 

November  i — Mr.  Hughes  difTblved  two  drams  of  nitre  in  a 
pint  of  a*!eco£lion  of  the  roots  of  afparagus,  and  added  to  it  two 
ounces  of  tindlure  of  rhubarb:  the  patient  took  a  fourth  part 
of  this  mixture  every  five  minutes,  till  he  had  taken  the  whole. 
— In  about  half  an  hour  he  made  eighteen  ounces  of  water, 
•which  was  very  manifeflly  tinged  with  the  rhubarb  •,  the  fmell 
of  afparagus  was  doubtful. 

He  then  loft  four  ounces  of  blood,  the  ferum  of  which  was 
not  fo  opaque  as  that  drawn  before,  but  of  a  yellowifh  caft,  as 
the  ferum  of  the  blood  ufually  appears. 

Paper  dipped  three  or  four  times  in  the  tinged  urine  and  dri- 
ed again,  did  not  fcintillate  when  is  was  fet  en  fire  :  but  when 

the 


SECT.  XXIX.  5.  1.  ABSORBENTS.  253 

the  flame  was  blown  out,  the  fire  ran  along  the  paper  for  half  an 
inch  ;  which,  when  the  fame  paper  was  unimpregnated,  it 
would  not  do  ;  nor  when  the  fame  paper  was  dipped  in  urine 
made  before  he  took  the  nitre,  and  dried  in  the  fame  manner. 

Paper,  dipped  in  the  ferum  of  the  blood  and  dried  in  the  fame 
manner  as  in  the  urine,  did  not  fcintillate  when  the  flame  was 
blown  out,  but  burnt  exactly  in  the  fame  manner  as  the  fame 
paper  dipped  in  the  ferum  of  blood  drawn  from  another  perfon. 

This  experiment,  which  is  copied  from  a  letter  of  Mr  .Hughes, 
as  well  as  the  former,  feems  to  evince  the  exiftence  of  another 
paflage  from  the  inteftines  to  the  bladder,  in  this  difeafe,  befides 
that  of  the  fanguiferous  fyliem  ;  and  coincides  with  the  curious 
experiment  related  in  fection  the  third,  except  that  the  f me  11  of 
the  afparagus  was  not  here  perceived,  owing  perhaps  to  the 
roots  having  been  made  ufe  of  inftead  of  the  heads. 

The  rifmg  in  the  throat  of  this  patient,  and  the  twitchings  of 
his  limbs,  feem  to  indicate  fome  fimilarity  between  the  diabetes 
and  the  hyiteric  difrafe,  befides  the  great  flow  of  pale  urine, 
which  is  common  to  them  both. 

Perhaps  if  the  mefenteric  glands  were  nicely  infpefted  in  the 
difledions  of  thefe  patients;  and  if  the  thoracic  duel,  and  the 
larger  branches  of  the  lacleals,  and  if  the  lymphatics,  which 
arile  from  the  bladder,  were  well  examined  by  injeclion,  or  by. 
the  knife,  the  caufe  of  diabetes  might  be  more  certainly  under- 
ftooci. 

The  opium  alone,  and  the  opium  with  the  refin,  feem  much 
to  have  ferveci  this  patient,  and  might  probably  have  effected  a 
cure,  if  the  difeafe  had  been  (lighter,  or  the  medicine  had  been 
exhibited,  before  it  had  been  confirmed  by  habit  during  the  fev- 
en  months  it  had  continued.  The  increafe  of  the  quantity  of 
water  on  beginning  the  large  dofes  of  refin  was  probably  owing 
to  his  omitting-the  morning  dofes  of  opium. 

As  the  urine  in  chyiiferous  diabetes  abounds  fo  much  with 
faccharine  matter,  as  appears  from  the  above  cafe  of  Davis,  Dr. 
Rollo  has  ingenioufly  recommended  a  diet  of  animal  food  alone  ; 
this,  with  a  diminution  of  the  quantity  of  fluid,  which  the  pa- 
tient was  previouily  accuitomed  to,  is  faid  to  have  changed  the 
quality  oi  the  urine,  and  to  have  diminifhed  its  quantity.  See 
Part  II  Clais  I.  3.  2.  6.  of  this  work. 

V.     The  Phenomena  of  Dropfies  explained. 

i.  SOME  inebriates  have  their  paroxyfms  of  inebriety  termin- 
ated by  much  pale  urine,  or  prof  ufe  fweats,  or  vomiting,  or 

(tools ; 


254  RETROGRADE.         SECT.  XXIX.  5.  i, 

ftools ;  others  have    their  paroxyfms  terminated  by  ftupor,  or 
fleep,  without  the  above  evacuations. 

The  former  kind  of  thefe  inebriates  have  been  obferved  to  be 
more  liable  to  diabetes  and  dropiy  ;  and  the  latter  to  gout, 
gravel,  and  leprofy.  Evoe  !  attend,  ye  bachannalians !  itart  at 
this  dark  train  of  evils,  and  amid  yfcur  inimodeft  jefts,  and  idiot 
laughter,  recoiled:, 

Quern  Deus  vult  perdere,  prius  dementat. 

In  thofe  who  are  fubjec"l  to  diabetes  and  dropfy,  the  abforbent 
veflels  are  naturally  more  irritable  than  in  the  latter  ;  and  by  be- 
ing frequently  diilurbed  or  inverted  by  violent  ftimlus,  and  by 
their  too  great  fympathy  with  each  other,  they  become  at  length 
either  entirely  paralytic,  or  are  only  fufceptible  of  motion  from 
the  flimulus  of  very  acrid  materials  •,  as  every  part  of  the  body, 
after  having  been  ufed  to  great  irritations,  becomes  lefs  affected 
by  fmaller  ones.  Thus  we  cannot  diftinguifh  obje&s  in  the 
night,  for  fome  time  after  we  come  out  of  a  ftrong  light,  though 
the  iris  is  prefently  dilated  ;  and  the  air  of  a  fummer  evening 
appears  cold,  after  we  have  been  expofed  to  the  heat  of  the  day. 

There  are  no  cells  in  the  body,  where  dropfy  may  not  be  pro- 
duced, if  the  lymphatics  ceafe  to  abiorb  that  mucilaginous  fluid, 
which  is  perpetually  depofited  in  them,  for  the  purpofe  of  lubri- 
cating their  furfaces. 

If  the  lymphatic  branch,  which  opens  into  the  cellular  mem- 
brane, either  does  its  office  imperfe6lly,  or  not  all  ;  thefe  cells 
become  replete  with  a  mucilaginous  fluid,  which,  after  it  has 
ftagnated  iome  time  in  the  cells,  will  coagulate  over  the  fire  ; 
and  is  trroneoufly  called  water.  Wherever  the  feat  of  this  dif- 
eafe  is,  (unlefs  in  the  lungs  or  other  pendent  viicera)  the  mucilag- 
inous liquid  above  mentioned  will  fubfide  to  the  moft  depend- 
ing parts  of  the  body,  as  the  feet  and  legs,  when  thofe  are  lower 
than  the  head  and  trunk  ;  for  all  thefe  cells  have  communica- 
tions with  each  other. 

When  the  cellular  abforbents  are  become  infenfible  to  their 
ufual  irritations,  it  moft  frequently  happens,  but  not  always, 
that  the  cutaneous  branch  of  abforbents,  which  is  flriclly  afibci- 
ated  with  them,  fufFers  the  like. inability.  And  then,  as  no  wa- 
ter is  abforbed  from  the  atmofphere,  the  urine  is  not  only  lefs 
diluted  at  the  time  of  its  fecretion,  and  confequently  in  lefs 
quantity  and  higher  coloured  :  but  great  thirft  is  at  the  fame 
time  induced,  for  as  no  water  is  abforbed  from  the  atmofphere 
to  dilute  the  chyle  and  blood,  the  Ia6leal&  and  other  abforbent 
veflels,  which  have  not  loft  their  powers,  are  excited  into  more 
conftant  or  more  violent  adion,  to  fupply  this  deficiency  ; 

whence 


SECT.  XXIX.  5.  i.        ABSORBENTS.  255 

whence  the  urine  becomes  (till  lefs  in  quantity,  and  of  a  deeper 
colour,  and  turbid  like  the  yolk  of  an  egg,  owing  to  a  greater  ab- 
forption  of  its  thinner  parts.  From  this  dronger  action  of  thofe 
abforbents,  which  (till  retain  their  irritability,  the  fat  is  alfo  ab- 
forbed,  and  the  whole  body  becomes  emaciated.  This  increafed 
exertion  of  fome  branches  of  the  lymphatics,  while  others  are 
totally  or  partially  paralytic,  is  refembled  by  what  conftantly  oc- 
curs in  the  hemiplegia  ;  when  the  patient  has  loft  the  ufeof  the 
limbs  on  one  fide,  he  is  inceflantly  moving  thofe  of  the  other  ; 
for  the  moving  power,  not  having  accefs  to  the  paralytic  limbs, 
becomes  redundant  in  thofe  which  are  not  difeafed. 

The  paucity  of  urine  and  third  cannot  be  explained  from  a 
greater  quantity  of  mucilaginous  fluid  being  depofited  in  the 
cellular  membrane  :  for  though  thefe  fymptoms  have  continued 
many  weeks,  or  even  months,  this  collection  frequently  does 
not  amount  to  more  than  very  few  pints.  Hence  alfo  the  dif- 
ficulty of  promoting  copious  fweats  in  anafarca  is  accounted  for, 
as  well  as  the  great  third,  paucity  of  urine,  and  lofs  of  fat ;  fince, 
when  the  cutaneous  branch  of  abforbents  is  paralytic,  or  nearly 
fo,  there  is  already  too  fmall  a  quantity  of  aqueous  fluid  in  the 
blood  :  nor  can  thefe  torpid  cutaneous  lymphatics  be  readily  ex- 
cited into  retrograde  motions. 

Hence  like  wife  we  underftand,  why  in  the  afcites,  and  fome 
other  dropfies,  there  is  often  no  third,  and  no  paucity  of  urine  ; 
in  thefe  cafes  the  cutaneous  abforbents  continue  to  do  their  office. 

Some  have  believed,  that  dropfies  were  occafioned  by  the  in- 
ability of  the  kidneys,  from  having  only  obferved  the  paucity  of 
urine  ;  and  have  thence  laboured  much  to  obtain  diuretic  medi- 
cines ;  but  it  is  daily  obfervable,  that  thofe  who  die  of  a  total  in- 
ability to  make  water,  do  not  become  dropfical  in  confequence 
of  it :  Fernelius  mentions  one,  who  laboured  under  a  perfect  fup- 
prefllon  of  urine  during  twenty  days  before  his  death,  and  yet 
had  no  fymptoms  of  clropfy..  Pathol.  1.  vi.  c.  8.  From  the 
fame  idea  many  phyficians  have  redrained  their  patients  from 
drinking,  though  their  third  has  been  very  urgent  ;  and  fome 
cafes  have  been  published,  where  this  cruel  regimen  has  been 
thought  advantageous  :  but  others  of  nicer  obfervation  are  of 
opinion, that  it  has  always  aggravated  thedidreiies  of  the  patient; 
and  though  it  has  abated  his  fwellings,  yet  by  inducing  a  fever  it 
has  hadened  his  diflblution.  See  Tranfattions  of  the  College, 
London,  vol.  ii.  p.  235.  Cafes  of  Dropfy  by  Dr.  G.  Baker. 

The  cure  of  anafarca,  fo  far  as  rclpefts  the  evacuation  of  the 
accumulated  fluid,  coincides  with  the  idea  of  the  retrograde  ac- 
tion of  the  lymphatic  fydem.  It  is  \vell  known  that  vomits,  and 
other  drugs,  which  induce  fickneis  or  naufea,  at  the  fame  time 

that 


256  RETROGRADE          SECT.  XXIX.  5.  2, 

that  they  evacuate  the  ftomach,  produce  a  great  abforption  of 
the  lymph  accumulated  in  the  cellular  membrane  In  the  op- 
eration of  a  vomit,  not  only  the  motions  of  the  ftomach  and  du- 
odenum become  inverted,  but  alfo  thofe  of  the  lymphatics  and 
lacleals,  which  belong  to  them  ;  whence  a  great  quantity  of 
chyle  and  lymph  is  perpetually  poured  into  the  llomach  and  in- 
teftines,  during  the  operation,  and  evacuated  by  the  mouth. 
Now  at  the  fame  time,  other  branches  of  the  lymphatic  fyflem, 
viz.  thofe  which  open  on  the  cellular  membrane,  are  brought  in- 
to more  energetic  action,  by  the  fympathy  above  mentioned,  and 
an  increafe  of  their  abforption  is  produced. 

Hence  repeated  vomits,  and  cupreous  falts,  and  fmall  dofes  of 
fquill  or  foxglove,  are  fo  efficacious  in  rhis  difraie.  And  as  draf- 
tic  purges  acl  alfo  by  inverting  the  motions  of  the  latleals  ;  and 
thence  the  other  branches  of  lymphatics  are  induced  into  more 
powerful  natural  adion,  by  fympathy,  and  drink  up  the  fluids 
from  all  the  cells  of  the  body  ;  and  by  their  anaitomOiCS.  pour 
them  into  the  lacleal  branches  •,  which,  by  their  inverted  aclions, 
return  them  into  the  inteftines  ,  and  they  are  thus  evacua- 
ted from  the  body  : — thefe  purges  alfo  are  uied  with  fuccefs  in 
difcharging  the  accumulated  fluid  in  anafarca. 

II.  The  following  cafes  are  related  with  defign  to  afcertnin 
the  particular  kinds  of  dropfy  in  which  the  digitalis  purpurea, 
or  common  foxglove,  is  preferable  to  fquill,  or  other  evacuants, 
and  were  firft  publifhed  in  1780,  in  a  pamphlet  entitled  Exper- 
iments on  mucilaginous  and  purulent  Matter,  &c.  Cadell.  Lon- 
don. Other  cafes  of  dropfy,  treated  with  digitalis,  were  after- 
wards publiftied  by  Dr  Darwin  in  the  Medical  Trania£Hons, 
vol.  iii.  in  which  there  is  a  miftake  in  refpedt  to  the  dofe  of  the 
powder  of  foxglove,  which  fhould  have  been  from  five  grains  to 
one,  inftead  of  from  five  grains  to  ten. 

Anafarca  of  the  Lungs. 

I.  A  lady,  between  forty  and  fifty  years  of  age,  had  been  in- 
difpofed  fome  time,  was  then  feized  with  cough  and  fever,  and 
afterwards  expectorated  much  digefted  mucus.  This  expeclo- 
ration  fuddenly  ceafed,  and  a  confiderabie  difficulty  of  breathing 
fupervened,  with  a  pulle  very  irregular  both  in  velocity  and 
flrength  ;  (he  was  much  diftrefled  at  firft  lying  down,  and  at 
firft  rifing  ;  but  after  a  minute  or  two  bore  either  of  thofe  atti- 
tudes with  eafe.  She  had  no  pain  or  numbnefs  in  her  arms  ; 
fhe  had  no  hectic  fever,  nor  any  cold  fhivenngs,  and  the  urine 
was  in  due  quantity,  and  of  the  natural  colour 

The  difficulty  of  breathing  was  twice  confiderably  relieved  by 

fmal! 


SECT.  XXIX.  5.  2.      ABSORBENTS.  257 

fmall  dofes  of  ipecacuanha,  which  operated  upwards  and  down- 
wards, but  recurred  in  a  few  days  :  the  was  then  dire&ed  a  de- 
codion  of  foxglove,  (digitalis  purpurea)  prepared  by  boiling  fout 
ounces  of  the  fre(h  leaves  from  two  pints  of  water  to  one  pint ; 
to  which  were  added  two  ounces  of  vinous  fpirit  \  fhe  took  three 
large  fpoonfuls  of  this  mixture  every  two  hours,  till  (he  had 
taken  it  four  times  ;  a  continued  ficknefs  fupervened,  with  fre- 
quent vomiting,  and  a  copious  flow  of  urine  :  thefe  evacuations 
continued  at  intervals  for  two  or  three  days,  and  relieved  the 
difficulty  of  breathing  — She  had  fome  relapfes  afterwards,  which 
were  again  relieved  by  the  repetition  of  the  decodion  of  foxglove. 

2.  A  gentlemen,  about  fixty  years  of  age,  who  had  been  ad- 
dicled  to  an  immoderate  ufe  of  fermented  liquors,  and  had  been 
very  corpulent,  gradually  loll  his  flrength  and  fleih,  had  great 
difficulty  of  breathing,  with  legs  fomewhat  fwelled,  and  a  very 
irregular  pulfe.     He  was  very  much  diftrefled  at  fir  ft  lying  down, 
and  at  firft  rifmg  from  his  bed,  yet  in  a  minute  or  two  was  eafy 
in  both  thefe  attitudes.     He  made  ftraw-coloured  urine  in   due 
quantity,  and  had  no  pain  or  numbnefs  of  his  arms. 

He  took  a  large  fpoonful  of  the  decoclion  of  foxglove, as  above, 
every  hour,  for  ten  or  twelve  fucceffive  hours  had  incefTant  fick- 
nefs for  about  two  days,  and  pafTed  a  large  quantity  of  urine  ; 
upon  which  his  breath  became  quite  eafy,  and  the  fwelling  of 
his  legs  fubfided  ;  but  as  his  whole  conflitution  was  already  fink- 
ing from  the  previous  intemperance  of  his  life,  he  did  not  furr" 
vive  more  than  three  or  four  mouths. 

Hydrops  Perlcardn. 

3.  A  gentleman  of  temperate  life  and  fedulous  application  rt> 
bufmefs,  between  thirty  and  forty   years  of  age,   had   long  been 
fubjeft,  at  intervals,  to  an  irregular  pulfe  :  a  few  months  ago  he 
became  weak,  with  difficulty  of  breathing,  and  dry  cough.     In 
this  (ituation  aphyfician  of  eminence  directed  him  to  abitain  from 
all  animal  food  and  fermented  liquor,  during  which  regimen  all 
his  complaints  increafed  \  he  now  became  emaciated,  and  total- 
ly loft  his  appetite  ;  his  pulfe  very  irregular  both  in  velocity  and 
ftrength  ;  with  great  difficulty   of  breathing,  and  fome  fwelling 
of  his  legs  ;  yet  he  could  lie  down  horizontally  in  his  bed  though 
he  got  little  fleep,  and  pafled  a  due  quantity  of  urine,  and  of  the 
natural  colour  :  no  fulnefs  or  hardnefs  could  be  perceived  about 
the  region  of  the  liver  ;  and  he  had  no  pain   or  numbnefs  in  his 
arms. 

»     One  night  he  had  a  moft  prof  ufe  fweat  all  over  his  body  and 

limbs  which^  quite  deluged  his  bed,  and  for  a  day  or  two  fome- 

VOL.  L  K  K  what 


258  RETROGRADE     SECT.  XXIX.  5.  2. 

what  relieved  his  difficulty  of  breathing,  and  his  pulfe  became 
iefs  irregular  :  this  copious  fweat  recurred  three  or  four  times  at 
the  intervals  of  five  or  fix  days,  and  repeatedly  alleviated  his 
fymptoms. 

He  was  directed  one  large  fpoonful  of  the  above  decoclion  of 
foxglove  every  hour,  till  it  procured  fome  confiderable  evacua- 
tion :  after  he  had  taken  it  eleven  fucceffive  hours  he  had  a 
few  liquid  ftools,  attended  with  a  great  flow  of  urine,  which  lad 
had  a  dark  tinge,  as  if  mixed  with  a  few  drops  of  blood  :  he 
continued  fick  at  intervals  for  two  days,  but  his  breath  became 
quite  eafy  and  his  pulfe  quite  regular,  the  fwelling  of  his  legs 
difappeared,  and  his  appetite  and  ileep  returned. 

He  then  took  three  grains  of  white  virtriol  twice  a  day,  with 
fome  bittter  medicines,  and  a  grain  of  opium  with  five  grains  of 
rhubarb  every  night  ;  was  advifed  to  eat  fleth  meat,  and  fpice, 
as  his  ftomach  would  bear  it,  with  fmall  beer,  and  a  few  glafles 
of  wine  ;  and  had  iflues  made  in  his  thighs  •,  and  has  fuffered 
no  relapfe. 

4.  A  lady,  about  fifty  years  of  age,  had  for  fome  weeks  great 
difficulty  of  breathing,  with  very  irregular  pulfe,  and  confidera- 
ble general  debility  :  fhe  could   lie  down  in  bed,  and   the  urine 
was  in  due  quantity  and  of  the  natural  colour,  and  fhe  had  no 
pain  or  numbnefs  of  her  arms. 

She  took  one  large  fpoonful  of  the  above  deco£tion  of  foxglove 
every  hour,  for  ten  or  twelve  fucceffive  hours  ;  was  fick,  and 
made  a  quantity  of  pale  urine  for  about  two  days,  and  was  quite 
relieved  both  of  the  difficulty  of  breathing,  and  the  irregularity 
of  her  pulfe.  She  then  took  a  grain  of  opium,  and  five  grains 
of  rhubarb,  every  night,  for  many  weeks  :  with  fome  flight  cha- 
lybeate and  bitter  medicines,  and  has  fuffered  no  relapfe. 

Hydrops  Thoracis. 

5.  A  tradefman,  about  fifty  years  of  age,  became  weak  and 
ihort  of  breath,  efpecially  on  increafe  of  motion,   with  pain  in 
one  arm,  about  the  infertion  of  the  biceps  mufcle.     He  obferv- 
ed  he  fometimes  in  the  night  made  an  unufual  quantity  of  pale 
water.     He  took  calomel,  alum,  and  peruvian  bark,  and  all  his 
fymptoms  increafed  :  his  legs  began  to  fwell  confiderably  ;  his 
breath  became  more  difficult,  and  he  could  not  lie  down  in  bed ; 
but  all  this  time  he  made  a  due  quantity  of  ftraw-coloured 
water. 

The  deco&ion  of  foxglove  was  given  as  in  the  preceding  ca- 
fes, which  operated  chiefly  by  purging,  and  feemed  to  relieve 
his  breath  for  a  day  or  two  ;  but  alfo  feemed  to  contribute  to 

weaken 


SECT.  XXIX.  5.  2.      ABSORBENTS.  259 

weaken  him. — He  became  after  fome  weeks  univerfally  dropfical, 
and  died  comatofe. 

6.  A  young  lady  of  delicate  conftitution,  with  light  eyes  and 
hair,    and  who  had  perhaps  lived  too  abftemioufly  both  in  refpe6t 
to  the  quantity  and  quality  of  what  (he  ate  and  drank,  was  ieiz- 
ed  with  great  difficulty  of  breathing,  fo  as  to  threaten  immedi- 
ate death.     Her  extremities  were  quite  cold,  and  her  breath  felt 
cold  to  the  back  of  one's  hand.     She  had  no  fweat,  nor  could 
lie  down  for  a  fingle  moment  ;  and  had  previoufly,  and  at  pref- 
ent,  complained  of  great  wcaknefs  and   pain  and  numbnefs  of 
both  her  arms  ;  had  no  fwelling  of  her  legs,  no  third,  water  in 
due  quantity  and  colour.     Her  filter,   about  a  year  before,  was 
affli£ted  with  fimilar  fymptoms,  was  repeatedly  blooded,  and  di- 
ed univerfally  dropfical. 

A  grain  of  opium  was  given  immediately,  and  repeated  every 
fix  hours  with  evident  and  amazing  advantage  ;  afterwards  a 
blifter,  with  chalybeates,  bitters,  and  efiential  oils,  were  exhibit- 
ed, but  nothing  had  fuch  eminent  effedt  in  relieving  the  difficul- 
ty of  breathing  and  coldnefs  of  her  extremities  as  opium,  by 
the  ufe  of  which  in  a  few  weeks  (he  perfectly  regained  her 
health,  and  has  fuffered  norelapfe. 

df cites. 

7.  A  young  lady  of  delicate  conftitution  having  been  expo- 
fed  to   great  fear,  cold,  and  fatigue,  by  the  overturn  of  a  chaife 
in  the  night,  began  with  pain  and    tumour  in  the  right  hypo- 
chondrium  :  in  a  few  months  a  fluctuation  was  felt  throughout 
the  whole  abdomen,  more  didindtly  perceptible  indeed  about  the 
region  of  the  ftomach  \  fince  the  integuments  of  the  lower  part 
of  the  abdomen,  generally   become  thickened  in  this  difeafe  by  a 
degree  of  anafarca.     Her  legs  were  not  fwelled,  no  third,  water 
in  due  quantity  and  colour. — She  took  the  foxglove  fo  as  to  in- 
duce ficknefs  and  ftools,   but  without  abating  the  fwelling,  and 
was  obliged  at  length  to  fubmit  to  the  operation  of  tapping. 

8.  A  man  about  fixty-feven,   who  had  long  been  accultomed 
to  fpirituous  potation,  had  fome  time  laboured   under  afcites  ; 
his  legs  fomewhat  fwelled  ;  his  breath  eafy  in  all  attitudes  ;  no 
appetite  \  great  third  ;  urine  in  exceedingly  fmall  quantity,  very 
deep  coloured,  and  turbid  \  pulfe  equal.     He  took  the  foxglove 
in  fuch  quantity  as  vomited  him,  and  induced  ficknefs  for  two 
days  ;  but  procured  no  flow  of  urine,  or  diminution  of  his  fwell- 
ing ;  but  was  thought  to  leave  him  confiderably  weaker. 

9.  A  corpulent  man,  accudomed  to  a  large  potation  of  fer- 
mented  liquors,  had  vehement  cough,  difficult  breathing,  ana- 
farca 


RETROGRADE        SECT.  XXIX.  5. 2. 

farca  of  his  legs,  thighs,  and  hands,  and  confiderable  tumour, 
with  evident  fluctuation  of  his  abdomen  ;  his  pulfe  was  equal ; 
his  urine  in  fmall  quantity,  of  deep  colour,  and  turbid.  Thefe 
fwellings  had  been  twice  confiderably  abated  by  draiVic  cathar- 
tics. He  took  three  ounces  of  a  deception  of  foxglove  (made 
by  boiling  one  ounce  of  the  frefh  leaves  in  a  pint  of  water)  every 
three  hours,  for  two  whole  days  ;  it  then  began  to  vomit  and 
purge  him  violently,  and  promoted  a  great  flow  of  urine  ;  he 
was  by  thefe  evacuations  completely  emptied  in  twelve  hours. 
After  two  or  three  months  all  thefe  fymptoms  returned,  and 
were  again  relieved  by  the  ufe  of  the  foxglove  :  and  thus  in  the 
fpace  of  about  three  years  he  was  about  ten  times  evacuated, 
and  continued  all  that  tirr^e  his  ufual  potations  :  excepting  at 
firit,  the  medicine  operated  only  by  urine,  and  did  not  appear 
confiderably  to  weaken  him. — The  lad  time  he  took  it,  it  had 
no  effect ;  and  a  few  weeks  afterwards  he  vomited  a  great  quan- 
tity of  blood,  and  expired, 

QUERIES. 

1.  As  the  firfl  fix  of  thefe  patients  had   a  due  difcharge  of 
urine,  and  of  the  natural  colour,  was  not  the  feat  of  the  difeafe 
confined  to  feme  part  of  the  thorax,  and  the  fwelling  of  the  legs 
rather    a   fymptom  of  the  obftrufted  circulation   of  the  blood, 
than  of  a  paralylisof  the  cellular  lymphatics  of  thofe  parts  ? 

2.  When  the  original  difeafe  is  a  general  anafarca,  do  not  the 
cutaneous  lymphatics  always  become  paralytic  at  the  fame  time 
with  the  cellular  ones,  by  their  greater  fympathy  with  each  oth- 
er ?  and  hence  the  paucity  of  urine,  and  the  great  third,  diftin- 
guiih  this  kind  of  dropfy  ? 

3.  In  the  anafarca  of  the  lungs,  when  the  difeafe  is  not  very 
great,  through  the  patients  have  confiderable  difficulty  of  breath- 
ing at  their  firft  lying  down,   yet  after  a  minute  or  two  their 
breath  becomes  eafy   again  ;  and   the  fame  occurs  at  their  firfl 
rifing.     Is  not  this  owing  to  the  time  necefTary  for  the  fluid  in 
the  cells  of  the  lungs  to  change  its  place,  fo  as  the  lead  to  incom- 
mode refpiration  in  the  new  attitude  ? 

4.  In  the  dropfy  of  the  pericardium  does  not  the  patient  bear 
the  horizontal  or  perpendicular  attitude  with  equal  eafe  ?  Does 
this  circumftance  diftinguim  the  dropfy  of  the  pericardium  from 
that  of  the  lungs  and  of  the  thorax  ? 

5.  Do  the  univerfal  fweats  diftinguifh  the  dropfy  of  the  peri- 
cardium,  or  of  the  thorax  ?  and  thofe,    which  cover  the  upper 
parts  of  the,  body  only,  the  anafarca  of  the  lungs  ? 

6.  When  in  the  dropiy  of  the  thorax,  the  patient  endeavours 

to 


SECT.  XXIX.  5. 2.        ABSORBENTS.  261 

to  lie  down,  does  not  the  extravafated  fluid  comprefs  the  upper 
parts  of  the  bronchia,  and  totally  preclude  the  accefs  of  air  to 
every  part  of  the  lungs ;  whilft  in  the  perpendicular  attitude  the 
inferiour  parts  of  the  lungs  only  are  comprefied  ?  Does  not  fome- 
thing  fimilar  to  this  occur  in  the  anafarca  of  the  lungs,  when 
the  difeafe  is  very  great,  and  thus  prevent  thofe  patients  alfo 
from  lying  down  ? 

7.  As  a  principal  branch  of  the  fourth  cervical  nerve  of  the 
left  fide,  after  having  joined  a  branch  of  the  third  and  of  the  fec- 
ond  cervical  nerves,  defcending  between  the  fubclavian  vein  and 
artery,  is  received  in  a  groove  formed  for  it  in  the  pericardium, 
and  is  obliged  to  make  a  confiderable  turn  outwards  to  go  over 
the  prominent  part  of  it  where  the  point  of  the  heart  is  lodged, 
in  its  courfe  to  the  diaphragm  ;  and  as  the  other  phrenic  nerve 
of  the  right  fide  has  a  itraight  courle  to  the  diaphragm ;   and  as 
many  other  coniiderable  branches  of  this  fourth  pair  of  cervical 
nerves  are  fpread  on  the  arms  •,  does  not  a  pain  in  the  left  arm 
diftinguifh  a  difeafe  of  the  pericardium,  as  in  the  angina  pefto- 
ris,  or   in  the  dropfy  of  the  pericardium  ?  and  does   not  a  pain 
or  weaknefs  in  both  arms  diftinguifh  the  dropfy  of  the  thorax  ? 

8.  Do  not  the  dropfies  of   the  thorax  and  pericardium  fre- 
quently exift  together,  and  thus  add  to  the  uncertainty  and  fa- 
tality of  the  difeafe. 

9.  Might  not  the  foxglove  be  ferviceable  in  hydrocephalus  in- 
ternus,  in  hydrocele,  and  in  white  fwellings  of  the  joints  ? 

VI.   Of  cold  Sweats. 

THERE  have  been  hiftories  given  of  chronical  immoderate 
fweatings,  which  bear  fome  analogy  to  the  diabetes.  Dr.  Willis 
mentions  a  lady  then  living,  whofe  fweats  were  for  many  years 
fo  profufe,  that  all  her  bed-clothes  were  not  only  moiftened, 
but  deluged  with  them  every  night ;  and  that  may  ounces,  and 
fometimes  pints,  of  this  fweat,  were  received  in  veflels  properly 
placed,  as  it  trickled  down  her  body.  He  adds,  that  (he  had 
great  thirft,  had  taken  many  medicines,  and  fubmitted  to  various 
rules  of  life,  and  changes  of  climate,  but  dill  continued  to  have 
thefe  immoderate  fweats.  Pharmac.  ration,  de  fudore  anglico. 

Dr.  Willis  has  alfo  obferved,  that  the  fudor  anglicanus  which 
appeared  in  England,  in  1483,  and  continued  till  1551,  was  in 
fome  refpee^s  fimilar  to  the  diabetes  ;  and  as  Dr.  Caius,  who 
Jaw  this  difeafe,  mentions  the  vifcidity  as  well  as  the  quantity 
of  thefe  fweats,  and  adds,  that  the  extremities  were  often  cold, 
when  the  internal  parts  were  burnt  up  with  heat  and  third, 
with  great  and  fpeedy  emaciation  and  debility  j  there  is  great 

reafon 


262  RETROGRADE         SECT.  XXIX  6.  i. 

reafon  to  believe,  that  the  fluids  were  abforbed  from  the  cells  of 
the  body  by  the  cellular  and  cyClic  branches  of  the  lymphatics, 
and  poured  on  the  fkin  by  the  retrograde  motions  of  the  cuta- 
neous ones. 

Sydenham  has  recorded,  in  the  flationary  fever  of  the  year 
1685,  the  vifcid  fweats  flowing  from  the  head,  which  were  prob- 
ably from  the  fame  fource  as  thofe  in  the  fweating  plague  above 
mentioned. 

It  is  very  common  in  dropfies  of  the  chefl  or  lungs  to  have 
the  difficulty  of  breathing  relieved  by  copious  fweats,  flowing 
from  the  head  and  neck.  Mr.  P.  about  fifty  years  of  age,  had 
for  many  weeks  been  afflicled  with  anafarca  of  his  legs  and  thighs, 
attended  with  difficulty  of  breathing ;  and  had  repeatedly  been 
relieved  by  fquill,  other  bitters,  and  chalybeates* — One  night 
the  difficulty  of  breathing  became  fo  great,  that  it  was  thought 
he  mult  have  expired  ;  but  fo  copious  a  fweat  came  out  of  his 
head  and  neck,  that  in  a  few  hours,  fome  pints,  by  eftimation, 
were  wiped  off  from  thofe  parts,  and  his  breath  was  for  a  time 
relieved.  This  dyfpncea  and  thefe  fweats  recurred  at  intervals, 
and  after  fome  weeks  he  ceafed  to  exiil.  The  fkin  of  his  head 
and  neck  felt  cold  to  the  hand,  and  appeared  pale  at  the  time  thefe 
fweats  flowed  fo  abundantly  ;  which  is  a  proof,  that  they  were 
produced  by  an  inverted  motion  of  the  abforbents  of  thofe  parts  : 
for  fweats,  which  are  the  confequence  of  an  increafed  a£lion  of 
the  fanguiferous  fyftem,  are  always  attended  with  a  warmth  of 
the  fkin,  greater  than  is  natural,  and  a  more  florid  colour ;  as 
the  fweats  from  exercife,  or  thole  that  fucceed  the  cold  fits  of 
agues.  Can  any  one  explain  how  thefe  partial  fweats  fhould  re- 
lieve the  difficulty  of  breathing  in  anafarca,  but  by  fuppofing 
that  the  pulmonary  branch  of  abforbents  drank  up  the  fluid  in  the 
cavity  in  the  thorax,  or  in  the  cells  of  the  lungs,  and  threw  it  on 
the  fkin,  by  the  retrograde  motions  of  the  cutaneous  branch  ? 
for,  if  we  could  fuppoie,  that  the  increafed  aclion  of  the  cuta- 
neous glands  or  capillaries  poured  upon  the  fkin  this  fluid,  pre- 
vioufly  abforbed  from  the  lungs  ;  why  is  not  the  whole  furface  of 
the  body  coveted  with  fweat  ?  why  is  not  the  fkin  warm  ?  Add 
to  this,  that  the  fweats  above  mentioned  were  clammy  or  gluti- 
nous, which  thecondenfed  perfpirable  matter  is  not;  whence  it 
would  ieem  to  have  been  a  different  fluid  from  that  of  common 
perfpiration. 

Dr.  Dobfon  of  Liverpool,  has  given  a  very  ingenious  expla- 
nation of  the  acid  fweats,  which  he  obferved  in  a  diabetic  patient 
— he  thinks  part  of  the  chyle  is  fecreted  by  the  fkin,  and  after- 
wards undergoes  an  acetous  fermentation, — Can  the  chyle  get 
thither,  but  by  an  inverted  motion  of  the  cutaneous  lymphatics  ? 

in 


SECT.  XXIX.  7.1.  ABSORBENTS.  263. 

in  the  fame  manner  as  it  is  carried  to  the  bladder,  by  the  inverted 
motions  of  the  urinary  lymphatics.  Medic.  Obfervat.  and 
Enq.  London,  vol.  v. 

Are  not  the  cold  fweats  in  fome  fainting  fits,  and  in  dying 
people,  owing  to  an  inverted  motion  of  the  cutaneous  lymphat- 
ics ?  for  in  thele  there  can  be  no  increafed  arterial  or  glandular 
action. 

Is  the  difficulty  of  breathing,  arifing  fromanafarcaof  the  lungs, 
relieved  by  fweats  from  the  head  and  neck;  whilft  that  difficul- 
ty of  breathing,  which  arifes  from  a  dropfy  of  the  thorax,  or 
pericardium,  is  never  attended  with  thefe  fweats  of  the  head  ? 
and  thence  can  thefe  difeafes  be  diftinguifhed  from  each  other  ? 
Do  the  periodic  returns  of  nocturnal  afthma  rife  from  a  tempo- 
rary dropfy  of  the  lungs,  collected  during  their  more  torpid  (late 
in  found  fleep,  and  then  re-abforbed  by  the  vehement  efforts  of 
the  difordered  organs  of  refpiration,  and  carried  off  by  the  co- 
pious fweats  about  the  head  and  neck  ? 

More  extend ve  and  accurate  diflections  of  the  lymphatic  fyi- 
tem  are  wanting  to  enable  us  to  unravel  thefe  knots  of  fcience. 

VII.    Tranjlations  of  Matter ',  of  Chyley  of  Milk,  of  Urine.     Oper- 
ation of  purging  Drugs  applied  externally. 

1.  THE  tranflations  of  matter  from  one  part  of  the  body  to 
another,  can  only  receive  an  explanation  from  the  doctrine  of 
the  occafional  retrograde  motions  of  fome  branches  of  the  lymph- 
atic fyftem :  for  how  can    matter  abforbed  and  mixed  with  the 
whole  mats  of  blood,  be    fo    haftily  collected  again  in  any  one 
part  ?    and  is   it  not  an  immutable  law,  in  animal  bodies,  that 
each  gland  can  fecrete  no  other,  but  its  own  proper  fluid  ?  which 
is,  in  part,    fabricated    in  the  very  gland  by  an  animal  procefs, 
which  it  there  undergoes  :  of  thefe  purulent  tranflations  innu- 
merable and  very  remarkable  inftances  are  recorded. 

2.  The  chyle,  which   is  feen  among  the  materials  thrown  up 
by  violent  vomi  \  ig,  or  in  purging  (tools,  can  only  come  thither 
by  its   having  been  poured  into  the  bowels  by  the  inverted  mo- 
tions of  thelafteals  :  for  our  aliment  is  not  converted  into  chyle 
in  the  ftomach  or  inreftines  by  a  chemical  procefs,  but  is  made 
in  the  very  mouths  of  the  lacteals  •,  or  in  the  mefenteric  glands  j 
in  the  fame  manner  as  o'ther  fecreted  fluids  are  made  by  an  ani- 
mal procefs  in  their  adapted  glands. 

Here  a  curious  phenomenon  in  the  exhibition  of  mercury  is 
worth  explaining  : — If  a  moderate  dofe  of  calomel,  as  fix  or  ten 
grains,  be  fwallowed,  and  within  one  or  two  days  a  cathartic  is 
given,  a  falivation  is  prevented  :  but  after  three  or  four  days,  a 

falivation 


264  RETROGRADE        SECT.  XXIX.  7.  5, 

falivation  having  come  on,  repeated  purges  every  day,  for  a  week 
or  two,  are  required  to  eliminate  the  mercury  from  the  conftitu- 
tion.  For  this  acrid  metallic  preparation,  being  abforbed  by  the 
mouths  of  the  ladteals,  continues,  for  a  time  arrefted  by  the  mef- 
enteric  glands,  (as  the  variolous  or  venereal  poifons  fwell  the 
fubaxillar  or  inguinal  glands) :  and,  during  the  operation  of  a 
cathartic,  is  returned  into  the  inteftines  by  the  inverted  action 
of  the  lac'reals,  and  thus  carried  out  of  the  fyitem. 

Hence  we  underftand  the  ufe  of  vomits  or  purges,  to  thofe 
who  have  fwallowed  either  contagious  or  poiionous  materials, 
even  though  exhibited  a  day  or  even  two  days  after  fuch  acci- 
dents ;  namely,  that  by  the  retrograde  motions  of  the  la£teals 
and  lymphatics,  the  material  Hill  arreited  in  the  mefenteric,  or 
other  glands,  may  be  eliminated  from  the  body. 

3.  Many  initances  of  milk  and  chyle  found  in  ulcers  are  giv- 
en by  Haller,  El.  Phyfiol.    t.  vii.  p.  12,  23,  which  admit  of  no 
other  explanation  than  by  fuppofmg,  that  the  chyle,  imbibed  by 
one  branch  of  the  abforbent  fyitem,  was  carried  ro  the  ulcer,  by 
the  inverted  motions  of  another  branch  of  the  fame  fyitem. 

4.  Mrs.  P.  on  the  fecond  day  after  delivery,  was  feized  with 
a  violent  purging,  in  which,  though  opiates  mucilages,  the  bark, 
and  teftacea  were  profufely    ufed,  continued  many  days,  till  at 
length  (he  recovered      During  the  time  of  this  purging,  no  milk 
could  be    drawn  from  her  breads  ;  but  the  (tools  appeared  like 
the  curd  of  milk  broken  into  fmall  pieces.     In  this  cafe,  was  not 
the  milk  taken  up  from  the  follicles  of  the  pectoral  glands,  and 
thrown  on  the  inteftines,  by  a   retrogreflion  of  the  inteitinal  ab- 
forbents  ?  for  how  can  v/e  fora  moment  iuipecl:  that  the  mucous 
glands  of  the  inteftines  could  feparate  pure  milk  from  the  blood  ? 
Dr.   Smellie   has   obterved,  that  loofe  (tools,  mixed  with  milk, 
which  is  curdled  in    the  inteftines,  frequently  relieves  the  tur- 
gefcency  of  the  breafts  of  thofe  who  ftudioufly  repel  their  milk. 
Cafes  in  Midwifery,  43,  No.  2.  i. 

5.  J.F.  Meckel  obferved  in  a  patient,  whofe  urine  was  in  fmall 
quantity  and  high  coloured,  that  a  copious  fweat  under  the  arniP' 
pits,  of  a  perfectly  urinous  fmell,  itained  the  linen  ;  which  ceaf- 
ed  again  when  the  ufual  quantity  of  urine  was  difcharged  by  the 
urethra.     Here  we  muft   believe  from  analogy,  that  the  urine 
was  firft  fecreted  in  the  kidneys,  then  re-abforbed  by  the  increaf- 
ed  action  of  the  urinary  lymphatics,  and  laftly  carried  to  the  ax- 
illse  by  the   retrograde  motions  of  the  lymphatic  branches  of 
thofe  parts.     As  in   the  jaundice  it  is  neceflary.  that  the  bile 
fhould  firft  be  fecreted  by  the  liver,  and  re-abforbed  into  the  cir- 
culation, to  produce   the  yellownefs  of  the  (kin  j  as  was  form- 
erly demonitrated  by  the  late  Dr.  Munro,  (Edin.  Medical  Ef- 

fays) 


SECT.  XXIX.  7.  6.        ABSORBENTS. 

fays)  and  if  in  this  patient  the  urine  had  been  reabforbed  into 
the  mafs  of  blood,  as  the  bile  in  the  jaundice,  why  was  it  not  de- 
te£led  in  other  parts  of  the  body,  as  well  as  in  the  arm-pits  ? 

6.  Cathartic  and  vermifuge  medicines  applied  externally  to 
the  abdomen,  feem  to  be  taken  up  by  the  cutaneous  branch  of 
lymphatics,  and  poured  on  the  inteftines  by  the  retrograde  mo- 
tions of  the  lafteals  without  having  pafled  the  circulation. 

For  when  the  draftic  purges  are  taken  by  the  mouth,  they  ex- 
cite the  la&eals  of  the  inteftines  into  retrograde  motions,  as  ap- 
pears from  the  chyle,  which  is  found  coagulated  among  the  fae- 
ces, as  was  (hewn  above,  (fe&.  2  and  4.)  And  as  the  cutaneous 
lymphatics  are  joined  with  the  lacteals  of  the  inteftines,  by  fre- 
quent anaftomofes  ;  it  would  be  more  extraordinary,  when  a 
ftrong  purging  drug,  abforbed  by  the  ikin,  is  carried  to  the  anaf- 
tomofing  branches  of  the  lacleals  unchanged,  if  it  fhould  not 
excite  them  into  retrograde  aclion  as  efficacioufly,  as  if  it  was 
taken  by  the  mouth,  and  mixed  with  the  food  of  the  ftomach. 

VIII.    Circumjlances  by  which  the  Fluids^  that  are  effnfed  by   the 
Retrograde  Motions  of  the  Abforbent  Vejfelsy  are  dijHnguiJhed* 

i.  WE  frequently  obferve  an  unufual  quantity  of  mucus  or 
other  fluids  in  fome  difeafes,  although  the  action  of  the  glands, 
by  which  thofe  fluids  are  feparated  from  the  blood,  is  not  un- 
uiually  increafed  ;  but  when  the  power  of  abforption  alone  isdi- 
minifhed.  Thus  the  catarrhal  humour  from  the  noftrils  of 
fome  who  ride  in  frofty  weather ;  and  the  tears  which  run 
down  the  cheeks  of  thofe,  who  have  an  obfiru&ion  of  the  punc- 
ta  lacrymalia  ;  and  the  ichor  of  thofe  phagedenic  ulcers,  which 
are  not  attended  with  inflammation,  are  all  inftancesof  this  ch> 
cumftance. 

Thefe  fluids  however  are  eafily  diftinguiihed  from  others  by 
their  abounding  in  ammoniacal  or  muriatic  falts  ;  whence  they 
inflame  the  circumjacent  (kin  :  thus  in  the  catarrh  the  upper  lip 
becomes  red  and  i  welled  from  the  acrimony  of  the  mucus,  and 
patients  complain  of  the  faltnefs  of  its  tafte.  The  eyes  and 
cheeks  are  red  with  the  corrofive  tears,  and  the  ichor  of  fome 
herpetic  eruptions  erodes  far  and  wide  the  contiguous  parts,  and 
ispungently  fait  to  thetafte,  us  fome  patients  have  informed  me, 

Whilft,  on  the  contrary,  thofe  fluids,  which  are  efFufed  by 
the  retrograde  aclion  of  the  lymphatics,  are  for  the  molt  part 
mild  and  innocent ;  as  water,  chyle,  and  the  natural  mucus  : 
or  they  take  their  properties  from  the  materials  previouily  ab- 
forbed, as  in  the  coloured  or  vinous  urine,  or  chat  fcented  with 
afparagus,  defcribed  before. 

VOL.  I.  I,  i,  2.  Whenever 


266  RETROGRADE        SECT.  XXIX.  8.  z. 

2.  Whenever  the  fecretion  of  any  fluid  is  increafed,  there  is 
at  the  fame  time  an  increafed  heat  in  the  part ;  for  the  fecreted 
fluid,  as  the  bile,  did  not  previously  exilt  in  the  mafs  of  blood, 
but  a  new  combination  is  produced  in  the  gland.     Now  as  folu- 
tions  are  attended  with  cold,  fo  combinations  are  attended  xvith 
heat ;  and  it  is  probable  the  fum  of  the  heat  given  out  by  all  the 
fecreted  fluids  of  animal  bodies  may  be  the  caufe  of  their  gen- 
eral heat  above  that  of  the  atmofphere. 

Hence  the  fluids  derived  from  increafed  fecretions  are  read- 
ily diftinguiihed  from  thofe  originating  from  the  retrograde  mo- 
tions of  the  lymphatics  :  thus  an  increafe  of  heat  of  either  in  the 
difeafed  parts,  or  diffufed  over  the  whole  body,  is  perceptible, 
when  copious  bilious  ftoois  are  confequent  to  an  inflamed  liver  ; 
or  a  copious  mucous  falivation  from  the  inflammatory  angina. 

3.  When  any  fecreted  fluid  is  produced  in  an  unufual  quanti- 
ty, and  at  the  fame  time  the  power  of  abforption  is  increafed  in 
equal  proportion,  not  only  the  heat  of  the  giand  becomes  more 
intenfe,  but  the  fecreted  fluid  becomes  thicker  and  milder,  its 
thinner  and  faline  parts  being  re-abforbed  :    and  thefe  are   dif- 
tinguifhable  both  by  their  greater  confidence,  and  by  their  heat, 
from  the  fluids,  which  are  effiifed  by  the  retrograde  motions  of 
the  lymphatics  ;  as  is  obfervable  towards  the  termination  of  gon- 
orrhoea, catarrh,  chincough.,  and  in  thofe  ulcers,  which  are  faid 
to  abound  with  laudable  pus. 

4.  When  chyle  is  obferved  in  ftoois,  or  among  the  materials 
ejeded  by  vomit,   we  may  be  confident  it  muft   have  been 
brought  thither  by  the  retrograde  motions  of  the  la&eals  ;  for 
chyle  does  not  previoufly  exift  amid  the  contents  of  the  intef- 
tines,  but  is  made  in  the  very  mouths  of  the  lafteals,  as  was  be- 
fore explained. 

5.  When  chyle,  milk,  or  other  extraneous  fluids  are  found  in 
the  urinary  bladder,  or  in  any  other  excretory  receptable  of  a 
gland  ;  no  one  can  for  a  moment  believe  that  thefe  have  been 
collected  from  the  mafs  of  blood  by  a  morbid  fecretion,  as  it  con- 
tradicts all  analogy. 

— — Aurea  dura 

Mala  ferant  quercus  ?     Narcifco  floreat  ainus  ? 
Pinguia  corticibus  fudent  ele&ra  myiica;  ? 

VIRGIL. 

IX.  Retrograde  Motions  of  Vegetable  Juices. 

THERE  are  bcfides  fome  motions  of  the  fap  of  vegetables, 
which  bear  analogy  to  our  prefent  fubjed ;  and  as  the  vegeta- 
ble tribes  are  by  many  philosophers  held  to  be  inferiour  animals, 

U 


SECT.  XXIX.  10.  i.         ABSORBENTS.  267 

it  may  be  a  matter  of  curiofity  at  lead  to  obferve,  that  their  ab- 
forbent  veflels  feem  evidently,  at  times,  to  be  capable  of  a  retro- 
grade motion.  Mr.  Perault  cut  off  a  forked  branch  of  a  tree, 
with  the  leaves  on  ;  and  inverting  one  of  the  forks  into  a  veflel 
of  water,  obferved,  that  the  leaves  on  the  other  branch  continu- 
ed green  much  longer  than  thofe  of  a  fimilar  branch,  cut  off 
from  the  fame  tree :  which  (hews,  that  the  water  from  the  vef- 
fel  was  carried  up  one  part  of  the  forked  branch,  by  the  retro- 
grade motion  of  its  veflels,  and  fupplied  nutriment  fome  time  to 
the  other  part  of  the  branch,  which  was  out  of  the  water.  And 
the  celebrated  Dr  Hales  found,  by  numerous  very  accurate  ex- 
periments, that  the  fap  of  trees  rofe  upwards  during  the  warmer 
hours  of  the  day,  and  in  part  defcended  again  during  the  cooler 
ones.  Vegetable  Statics. 

It  is  well  known  that  the  branches  of  willows,  and  of  many 
other  trees,  will  either  take  root  in  the  earth  or  ingraft  on  other 
trees,  fo  as  to  have  their  natural  direction  inverted,  and  yet  flour- 
ilh  with  vigour. 

Dr.  Hope  has  alfo  made  this  pleafing  experiment,  after  the 
manner  of  Hales — he  has  placed  a  forked  branch,  cut  from  one 
tree,  erect  between  two  others  ;  then  cutting  off  a  part  of  the 
bark  from  one  fork  applied  it  to  a  fimilar  branch  of  one  of  the 
trees  in  its  vicinity  ;  and  the  fame  of  the  other  fork  ;  fo  that  a 
tree  is  feen  to  grow  fufpended  in  the  air,  between  two  other 
treees  •>  which  fupply  their  fofter  friend  with  due  nourifliment. 

Miranturque  novas  frondes,  et  non  fua  poma 

All  thefe  experiments  clearly  evince,  that  the  juices  of  vege- 
tables can  occafionally  pafs  either  upwards  or  downwards  in 
their  abforbent  fyftem  of  veflels. 

X.     Objections   anfivered. 

THE  following  experiment,  at  firft  view,  would  feem  to  in- 
validate this  opinion  of  the  retrograde  motions  of  the  lymphatic 
veflels,  in  fome  difeafes. 

About  a  gallon  of  milk  having  been  given  to  a  hungry  fwine, 
he  was  fuffered  to  live  about  an  hour,  and  was  then  killed  by  a 
llroke  or  two  on  his  head  with  an  axe, — On  opening  his  belly 
the  lacleals  were  well  feen  filled  with  chyle  ;  on  irritating  ma- 
ny of  the  branches  of  them  with  a  knife,  they  did  not  appear 
to  empty  themfelves  haftily  ;  but  they  did  however  carry  for- 
wards their  contents  in  a  little  time. 

I  then  pafl"ed  a  ligature  round  fever al  branches  of  lacleals, 
and  irritated  them  much  with  a  knife  beneath  the  ligature>  but 

could 


265  RETROGRADE        SECT.  XXIX.  n.  tv 

eould  not  make  them  regurgitate  their  contained  fluid  into  the 
bowels. 

I  am  not  indeed  certain,  that  the  nerve  was  not  at  the  fame 
time  included  in  the  ligature,  and  thus  the  lymphatic  rendered 
unirritable  or  lifelefs  ;  but  this  however  is  certain,  that  it  is  riot 
any  quantity  of  any  ftimulus,  which  induces  the  veflels  of  animal 
bodies  to  revert  their  motions  ;  but  a  certain  quantity  of  a  cer- 
tain ftimulus,  as  appears  from  wounds  in  the  ftomach,  which  do 
not  produce  vomiting  ;  and  wounds  of  the  inteftines,  which  do 
not  produce  the  cholera  morbus. 

At  Nottingham,  a  few  years  ago,  two  flioemakers  quarrelled, 
and  one  of  them  with  a  knife,  which  they  ufe  in  their  occupation, 
(tabbed  his  companion  about  the  region  of  the  ftomach.  On 
opening  the  abdomen  of  the  wounded  man  after  his  death  the 
food  and  medicines  he  had  taken  were  in  part  found  in  the  cav- 
ity of  the  belly,  on  the  outfide  of  the  bowels  ;  and  there  was  a 
wound  about  half  an  inch  long  at  the  bottom  of  the  ftomach  ; 
which  I  fuppofe  was  diftended  with  liquor  and  food  at  the  time 
of  the  accident  j  and  thence  was  more  liable  ro  be  injured  at  its 
bottom  :  but  during  the  whole  time  he  lived,  which  was  about 
ten  days,  he  had  no  efforts  to  vomit,  nor  ever  even  complained 
of  being  lick  at  the  ftomach  !  Other  cafes  fimilar  to  this  are 
mentioned  in  the  philofophical  tranfadions. 

Thus,  if  you  vellicate  the  throat  with  a  feather,  naufea  is  pro- 
ductd  ;  if  you  wound  it  with  a  penknife,  ain  is  induced,  but 
not  ficknefs.  So  if  the  foles  of  the  fret  of  children  or  their  arm- 
pits are  tickled,  convulfive  laughter  is  excited,  which  ceafet  the 
moment  the  hand  is  applied,  to  as  to  rub  them  more  forcibly. 

The  experiment  therefore  above  related  upon  the  lacleals  of 
a  dead  pig,  which  were  included  in  a  ftricl  ligature,  proves 
nothing  ;  as  it  is  not  the  quantity,  but  the  kind  of  ftimulus, 
which  excites  the  lymphatic  veiTels  into  retrograde  motion. 

XI   The  Caufes  which  Induce  the  Retrograde  Motions  of  Animal  Vef- 
fels  ;  and  the  medicines    by  'which  the  Natural  Motions  are  rejlored, 

1.  SUCH    is   the  conftru&ion  of  animal  bodies,  that  all  their 
parts,  which  are  fubjecied   to  lefs  ftimuli  than  nature  defigned, 
perform  their  functions  with  lefs  accuracy  :  thus,  when  too  wa- 
tery or  too  acefcent  food  is  taken  into  the  ftomach,  indigeflion, 
and  flatulency,  and  heartburn  fucceed. 

2.  Another  law    of  irritation,  connate  with  our  exiftence,  is, 
that  all  thofe  parts  of  the   body,  which  have  previoufly  been  ex- 
pofed  to  too   great  a  quantity  of  fuch  ftimuli,  as  ftrongly  affect 
thera,  become  for  fome  time  afterwards  difobedient  to  the  nat- 
ural 


SECT.  XXIX.  1 1. 3.  ABSORBENTS.  a% 

ural  quantity  of  their  adapted  ftimuli. — Thus  the  eye  is  inca- 
pable of  feeing  objects  in  an  obfcure  room,  though  the  iris  is 
quite  dilated,  afrer  having  been  expofed  to  the  meridian  fun. 

3.  There  is  a  third  law  of  irritation,  that  all  the  parts  of  our 
bodies,   which  have  been  lately  fubjecled  to  lefs  ftimulus,   than 
thf  y  have  been  accuflomed  to,   when  they  are  expofed  to  their 
uiual  quantity  of  ftimulus,  are  excited  into  more  energetic  mo- 
tions ;   thus  when  we  come  from  a  dufky  cavern  into  the  glare 
of  day-light,  our  eyes  are  dazzled  ;  and  after  emerging  from  the 
cold  bath,  the  fkin  becomes  warm  and  red. 

4.  There  is  a  fourth  law  of  irritation,  that  all  the  parts  of  our 
bodies,  which  are  fuojecled  to  (till  ftronger  ftimuli  for  a  length 
of  time,   become    torpid,  and  refufe  to  obey  even  thefe  ftronger 
ftimuli  ;  and  thence  do  their  offices  very  imperfectly  — ^-Thus,  if 
any  one  looks  earneftly  for  fome  minutes,  on  an  area,  an  inch  di- 
ameter, of  red  fiik,  placed   on  a  (heet  of  white  paper,  the  image 
of  the  filk  will  gradually  become  pale,  and  at  length  totally  vanifh. 

5.  Nor  is  it  the    nerves  of  fenfe  alone,  as  the  optic  and  audi- 
tory nerves,  that  thus  become  torpid,  when  the  ftimulus  is  with- 
drawn  or  their  irritability    decrcafed  ;  but  the  motive  mufcles, 
when  they  are   deprived  of  their  natural  ftimuli,  or  of  their  irri- 
tability, become  torpid    and  paralytic  ;  as  is  feen  in  the  tremu- 
lous hand  of  the  drunkard  in  a  morning  ;    and  in  the  awkward 
ftep  of  age. 

The  hollow  mufcles  alfo,  of  which  the  various  veflels  of  the 
body  are  conftruded,  when  they  are  deprived  of  their  natural 
ftimuli,  or  of  rheir  due  degree  of  irritability,  not  only  become 
tremulous,  as  the  arterial  puifations  of  dying  people  j  but  alfo 
frequently  invert  their  motions,  as  in  vomiting,  in  hyfteric  fu fib- 
cations,  and  diabetes  above  defcribed. 

I  muft  beg  your  patient  attention,  for  a  few  moments,  whilft 
I  endeavour  to  explain,  how  the  retrograde  actions  of  our  hol- 
low mufcles  are  the  confequence  of  their  debility ;  as  the  tremu- 
lous actions  of  the  folid  mufcles  are  the  confequence  of  their  de- 
biliy.  When,  through  fatigue,  a  mufcle  can  act  no  longer;  the 
antagoniil  mufcles,  either  by  their  inanimate  elafticity,  or  by 
their  animal  aclion,  draw  the  limb  into  a  contrary  direction  :  in 
the  folid  mufcles,  as  thofe  of  locomotion,  their  actions  are  aflb- 
ciated  in  tribes,  which  have  been  accuftomed  to  fynchronous  ac- 
tion only  ;  hence  when  they  are  fatigued,  only  a  (ingle  contrary 
effort  takes  place  ;  which  is  either  tremulous,  when  the  fatigued 
rmifcles  are  again  immediately  brought  into  action  ;  or  it  is  a 
pamiiculution,  or  ftretching,  where  they  are  not  immediately 
Hgain  brought  into  action. 

Now  the  motions  of  the  hollow  mufcle?,  as  they  in  general 

propel 


270  RETROGRADE    SECT.  XXIX.  11.  6. 

propel  a  fluid  along  their  cavities,  are  aflbciated  in  trains,  which 
have  been  accultotned  to  fucceffive  adtions  :  hence  when  one 
ring  of  fuch  a  mufcle  is  fatigued  from  its  too  great  debility,  and 
is  brought  into  retrograde  action,  the  next  ring  from  its  aflbcia- 
tion  falls  fucceflively  into  retrograde  action  •,  and  fo  on  through* 
out  the  whole  canal.  See  Seel:.  XXV.  6. 

6'  But  as  the  retrograde  motions  of  the  ftomach,  cefophagus, 
and  fauces  in  vomiting  are,  as  it  were,  apparent  to  the  eye  5  we 
(hall  confider  this  operation  more  minutely,  that  the  fimilar  op- 
erations in  the  more  recondite  parts  of  our  fyftem  may  be  eafier 
underftood. 

From  certain  naufeous  ideas  of  the  mind,  from  an  ungrateful 
tafte  in  the  mouth,  or  from  foetid  fmells,  vomiting  is  fometimes 
inftantly  excited  ;  or  even  from  a  ftroke  on  the  head,  or  from, 
the  vibratory  motions  of  a  (hip  ;  all  which  originate  from  aflb- 
ciation,  or  fympathy.  See  Seel-  XX.  on  Vertigo. 

But  when  the  ftomach  is  fubjedted  to  a  lefs  ftimulus  than  is 
natural,  according  to  the  firfl  law  of  irritation  mentioned  above, 
its  motions  become  diilurbed,  as  in  hunger  ;  fid!  pain  is  produ- 
ced, then  ficknefs,  and  ai  length  vain  efforts  to  vomit,  as  many 
authors  inform  us. 

But  when  a  great  quantity  of  wine,  or  of  opium,  is  fwallow- 
ed,  the  retrograde  motions  of  the  ftomach  do  not  occur  till  after 
feveral  minutes,  or  even  hours;  for  when  the  power  of  fo  ftrong 
a  ftimulus  ceafes,  according  to  the  fecond  !aw  of  irritation,  men- 
tioned above,  the  periftaltic  motions  become  tremulous,  and  at 
length  retrograde  i  as  is  well  known  to  the  drunkard,  who  on 
the  next  morning  has  ficknefs  and  vomitings. 

When  a  ftill  greater  quantity  of  wine,  or  of  opium,  or  when 
naufeous  vegetables,  or  itrong  bitters,  or  metallic  falts,  are  taken 
into  the  ftomach,  they  quickly  induce  vomiting  ;  though  all 
thefe  in  lefs  dofes  excite  the  ftomach  into  more  energetic  acHon, 
and  ftrengthen  the  digeftion  j  as  the  flowers  of  chamomile,  and 
the  vitriol  of  zinc  :  for,  according  to  the  fourth  law  of  irritation, 
the  ftomach  will  no;  long  be  obedient  to  a  ftimulus  fo  much 
greater  than  is  natural  ;  but  its  action  becomes  firft  tremulous 
and  then  retrograde. 

7.  When  the  motions  of  any  veflels  become  retrograde,  lefs 
heat  of  the  body  is  produced  ;  for  in  paroxyfms  of  vomiting,  of 
hyiteric  affecYions,  of  diabetes,  of  afthma,  the  extremities  of  the 
body  are  cold  :  hence  we  may  conclude,  that  thefe  fymptoms 
arile  from  the  debility  of  the  parts  in  adHon  •,  for  an  increafe  of 
mufcuiar  adlion  is  always  attended  with  increafe  of  heat. 

8  But  as  animal  debility  is  owing  to  defedl  of  ftimulus,  or  to 
defect  of  irritability,  as  (hewn  above,  the  method  of  cure  is  eafily 

deduced  ; 


SECT.  XXIX.  n.  8.        ABSORBENTS.  271 

deduced:  when  the  vafcular  mufcles  are  not  excited  into  their 
due  aftion  by  the  natural  ftimuli,  we  fhould  exhibit  thofe  med- 
icines, which  poflefs  a  dill  greater  degree  of  ftimulus  ;  amongft 
thefe  are  the  foetids,  the  volatiles,  aromatics,  bitters,  metallic 
falts,  opiates,  *rine,  which  indeed  mould  be  given  in  fmall  dofes, 
and  frequently  repeated.  To  thefe  mould  be  added  conitant, 
but  moderate  exercife,  cheerfulnefs  of  mind,  and  change  of 
country  to  a  warmer  climate  ;  and  perhaps  occafionally  the  ex- 
ternal (timulus  of  blifters. 

It  is  alfo  frequently  ufeful  to  diminim  the  quantity  of  natur- 
al ftimulus  for  amort  time,  by  which  afterwards  the  irritability 
of  the  fyftem  becomes  increafed  •,  according  to  the  third  law  of 
irritation  above  mentioned,  hence  the  ufe  of  baths  fomewhat 
colder  than  animal  heat,  and  of  equitation  in  the  open  air. 

The  catalogue  of  difeafes  owing  to  the  retrograde  motions  of  lymphat- 
ics is  here  omitted,  as  it  will  appear  in  another  place  in  this 
•work.  The  following  is  the  conclufton  to  this  thejis  of  Mr. 
CHARLES  DARWIN. 

THUS  have  I  endeavoured  in  a  concife  manner  to  explain  the 
numerous  difeafes,  which  deduce  their  origin  from  the  inverted 
motions  of  the  hollow  mufcles  of  our  bodies  :  and  it  is  probable, 
that  Saint  Vitus's  dance,  and  the  ftammering  of  fpeech,  origin- 
ate from  a  fimilar  inverted  order  of  the  aflbciated  motions  of 
fome  of  the  folid  mufcles  ;  which,  as  it  is  foreign  to  my  prefent 
purpofe,  I  (hall  not  here  difcufs. 

I  beg,  illuftrious  profeflbrs,  and  ingenious  fellow- fludents, 
that  you  will  re^lleft  how  difficult  a  tafk  I  have  attempted,  to 
evince  the  retrograde  motions  of  the  lymphatic  vefTels,  when  the 
veflels  themfelves  for  fo  many  ages  efcaped  the  eyes  and  glades 
of  philofophers  :  and  if  you  are  not  yet  convinced  of  the  truth 
of  this  theory,  hold,  I  entreat  you,  your  minds  in  fufpenfe,  till 
ANATOMY  draws  her  fword  with  happier  omens,  cuts  afunder 
the  knots,  which  entangle  PHYSIOLOGY  \  and,  like  an  augur in- 
fpefting  the  immolated  victim,  announces  to  mankind  the  wif- 
domofHEAVEN. 


SFCX 


272  PARALYSIS       SECT.  xxx.  i.  *, 

SECT.      XXX, 

PARALYSIS   OF      THE    LIVER    AND    KIDNEYS, 

I.  Bile-duels  lefs  irritable  after  having  been  Jtimttlated  much .  a, 
Jaundice  from  par  a  ty  (is  of  the  bile- duel 3  cured  by  elecJric  Jhockr* 
3,  From  bile-jiones.  Experiments  on  bile  ftones,  Oil  vomit, 
4  Paify  of  the  liver  y  two  cafes.  5.  Scirrhofity  of  the  liver. 
6.  Large  livers  of  gcefe.  II.  Paralyjis  of  the  kidneys.  III. 
Story  of  Prometheus. 

i.  FROM  the  ingurgitation  of  fpirituous  liquors  into  the  (lorn.-, 
ach  and  duodenum,  the  termination  of  the  common  bile-duel:  in 
that  bowel  becomes  ftimulated  into  unnaural  action,  and  a 
greater  quantity  of  bile  is  produced  from  all  the  fecretory  veflels 
of  the  liver,  by  the  aflbciation  of  their  motions  with  thofe  of 
their  excretory  duels  ;  as  has  been  explained  in  Section  XXIV. 
and  XXV.  but  as  all  parts  of  the  body,  that  have  been  affected 
with  ftronger  ftimuli  for  any  length  of  time,  become  lefs  fuf- 
ceptible  of  motion,  from  their  natural  weaker  ftimuli.  it  follows, 
that  the  motions  of  the  fecretory  veiTels,  and  in  confequence  the 
fecretion  of  bile,  is  lefs  than  is  natural  during  the  intervals  of 
fobriety.  2.  If  this  ingurgitation  of  fpiritous  liquors  has  been 
daily  continued  in  confiderable  quantity,  and  is  then  fuddenly 
intermitted,  a  languor  or  paraiyfis  of  the  common  bile-duel:  is 
induced  ;  the  bile  is  prevented  from  being  poured  into  the  in- 
terlines ;  and  as  the  bilious  abforbents  are  ftimulated  into  ftrong- 
er aclionby  its  accumulation,  and  by  the  acrimony  or  vifcidity, 
which  it  acquires  by  delay,  it  is  abforbed,  and  carried  to  the 
receptacle  of  the  chyle  ;  or  otherwife  the  fecretory  veffels  in  the 
liver,  by  the  above-mentioned  ftimulus,  invert  their  motions,  an^ 
regurgitate  their  contents  into  the  blood,  as  fometimes  happens 
to  the  tears  in  the  lacrymal  fack,  fee  Seel.  XXIV.  2.  7.  and  one 
kind  of  jaundice  is  brought  on. 

There  is  reafon  to  believe,  that  the  bile  is  moft  frequently  re- 
turned into  the  circulation  by  the  inverted  motions  ofthefe  he- 
patic glands,  for  the  bile  does  not  feem  liable  to  be  abforbed  by 
the  lymphatics,  for  it  foaks  through  the  gall-duels,  and  is  fre- 
quently found  in  the  cellular  membrane.  This  kind  of  jaundice 
is  not  generally  attended  with  pain,  neither  at  the  extremity  of 
the  bile-duel,  where  it  enters  the  duodenum,  nor  on  the  region 
of  the  gall-bladder. 

Mr.  S.  a  gentleman  between  forty  and  fifty  years  of  age*  had 
had  the  jaudice  about  fix;  weeks,  without  pain,  ficknefs,  or  fe- 
ver; 


SECT.  XXX.  i.  3.        OP  THE  LIVER.  273 

ver  •,  and  had  taken  emetics,  cathartics,  mercurials,  bitters, 
chalybeates,  eflential  oil,  and  scther,  without  apparent  advan- 
tage. On  a  fuppofition  that  the  obftruction  of  the  bile  might 
be  owing  to  the  paralyiis,  or  torpid  action  of  the  common  bile- 
duft,  and  the  (limulants  taken  into  the  (lomach  feeming  to  have 
no  efFecl,  I  direfted  halt  a  fcore  fmart  eleclric  (liocks  from  a 
coared  bottle,  which  lield  about  a  quart,  to  be  pa  (fed  through 
the  liver,  and  along  the  courfe  of  the  common  gall-duel,  as  near 
as  could  be  guefled,  and  on  that  very  day  the  {tools  became  yel- 
low ;  he  continued  the  eleclric  (hocks  a  few  days  more,  and 
his  (kin  gradually  became  clear. 

3.  The  bilious  vomiting  and  purging,  that  affecls  fome  peo- 
ple by  intervals  of  a  few  weeks,  is  a  lefs  degree  of  this  difeafe; 
the  bile-duel:  is  lefs  irritable  than  natural,  and  hence  the  bile 
becomes  accumulated  in  the  gall-bladder,  and  hepatic  duels, 
till  by  its  quantity,  acrimony  or  vifcidity,  a  greater  degree  of 
irritation  is  produced,  and  it  is  fuddenly  evacuated,  or  laftly 
from  the  abforption  of  the  more  liquid  parts  of  the  bile,  the  re- 
mainder becomes  infpilTated,  and  cryftallizcs  into  mafles  too 
large  to  pafs,  and  forms  another  kind  of  jaundice,  where  the 
bile-duel  is  not  quite  paralytic,  or  has  regained  its  irritability. 

This  difeafe  is  attended  with  much  pain,  which  at  firft  is  felt 
at  the  pit  of  the  (tomach,  exactly  in  the  centre  of  the  body, 
where  the  bile-duel  enters  the  duodenum  ;  afterwards,  when 
the  fize  of  the  bile- (tones  increafe  it  is  alfo  felt  on  the  Tight 
fide,  where  the  gall-bladder  is  (ituated.  The  former  pain  at  the 
pit  of  the  (tomach  recurs  by  intervals,  as  the  bile-done  is  pufh- 
ed  againft  the  neck  of  the  duel  ;  like  the  paroxyfms  of  the  (lone 
in  the  urinary  bladder,  the  other  is  a  more  dull  and  conilant  pain. 

Where  thefe  bile-ftones  are  too  large  to  pafs,  and  the  bile- 
duels  poffefs  their  fenfibility,  this  becomes  a  very  painful  and 
hopelefs  difeafe.  I  made  the  following  experiments  with  a  view 
to  their  chemical  folution. 

Some  fragments  of  the  fame  bile- (tone,  were  put  into  the  wealc 
fpirit  of  marine  fait,  which  is  fold  in  the  (hops  ;  and  into  folu- 
tion of  mild  alkali ;  and  into  a  folution  of  cauftic  alkali ;  and 
into  oil  of  turpentine  ;  without  their  being  diflblved.  All  thefe 
mixtures  were  after  fome  time  put  into  a  heat  of  boiling  water, 
and  then  the  oil  of  turpentine  diflblved  its  fragments  of  bile-» 
(tone,  but  no  alteration  was  produced  upon  thofe  in  the  other 
liquids  except  fome  change  of  their  colour. 

Some  fragments  of  the  fame  bile- (lone  were  put  into  vitriolic 
aether,  and  were  quickly  difiblved  without  additional  heat. 
Might  not  sether  mixed  with  yolk  of  egg  or  with  honey  be  given 
<*dvantageou(ly  in  bilious  concretions  ? 

VOL.  I.  MM  I  have 


274  PARALYSIS  SECT.  XXX.  1.4. 

I  have  in  .two  inflances  feen  from  thirty  to  fifty  bile-ftones 
come  away  by  ftool,  about  the  fize  of  large  peas,  after  having 
given  fix  grains  of  calomel  in  the  evening,  and  four  ounces  of 
oil  of  almonds  or  olives  on  the  fucceeding  morning.  I  have 
alfo  given  half  a  pint  of  good  olive  or  almond  oil  as  an  emetic 
during  the  painful  fit,  and  repeated  it  in  half  an  hour,  if  the 
firft  did  not  operate,  with  frequent  good  effeft. 

4.  Another  dife*.fe  of  the  liver,  which  I  have  feveral  times  ob- 
ferved,  confifts  in  the  inability  or  paralyfis  of  the  fecretory  vef- 
fds.     This  difeafe  has  generally  the  fame  caufe  as  the  preceding 
one,  the  too  frequent  potation  of  fpirituous  liquors,   or  the  too 
fudden  o  million  of  them,  after  the  habit  is  confined  ;  and  is 
greater  or  lefs  in  proportion,  as  the  whole  or  a  part  of  the  liver 
is  affetled,  and  as  the  inability  or  paralyfis  is  more  or  lefs  com- 
plete. 

This  palfy  of  the  liver  is  known  from  thefe  fymptoms,  the  pa- 
tients have  generally  pafled  the  meridian  of  life,  have  drunk 
fermented  liquors  daily,  but  perhaps  not  been  opprobrious 
drunkards  ;  they  lofe  their  appetite,  then  their  flefh  and  ftrength 
diminifli  in  confequence,  there  appears  no  bile  in  their  ftools, 
nor  in  their  urine,  nor  is  any  hardnefs  or  fwelling  perceptible 
in  the  region^of  the  liver.  But  what  is  peculiar  to  this  difeafe, 
and  diflinguimes  it  from  all  others  at  the  firft  glance  of  the  eye, 
is  the  bombycinous  colour  of  the  fkin,  which,  like  that  of  full- 
grown  filk  worms,  has  a  degree  of  tranfparency  with  a  yellow 
tint  not  greater  than  is  natural  to  the  ferum  of  the  blood. 

Mr.  C.  and  Mr.  B.  both  very  ftrong  men,  between  fifty  and 
fixty  years  of  age,  who  had  drunk  ale  at  their  meals  inftead  of 
fmall  beer,  but  were  not  reputed  hard  drinkers,  fuddenly  became 
weak,  loft  their  appetite,  flefh  and  ftrength,  with  all  the  fymp- 
toms above  enumerated,  and  died  in  about  two  months  from  the 
beginning  of  their  malady.  Mr  C.  became  anafarcous  a  few 
days  before  his  death,  and  Mr  B.  had  frequent  and  great  haem- 
orrhages from  an  iflue,  and  fome  parts  of  his  mouth,  a  few 
days  before  his  death.  In  both  thefe  cafes  calomel,  bitters,  and 
chalybeates  were  repeatedly  ufed  without  efFeft. 

One  of  the  patients  defcribed  above,  Mr.  C.  was  by  trade  a 
plumber  ;  both  of  them  could  digeft  no  food,  and  died  apparent- 
ly for  want  of  blood.  Might  not  the  transfufion  of  blood  be 
ufed  in  thefe  cafes  with  advantage  ? 

5.  When  the  paralyfis  of  the  hepatic  glands  is  lefs  complete, 
or  lefs  univerfal,  a  fcirrhofity  of  fome  part  of  the  liver  is  indu- 
ced j  for  the  fecretory  veflels  retaining  fome  of  their  living  pow- 
er take  up  a  fluid  from  the  circulation,  without  being  fufficient- 
ly  irritable  to  carry  it  forwards  to  their  excretory  duds  ;  hence 

the. 


SECT.  XXX.  i.  6.        OF  THE  LIVER.  275 

the  body,  or  receptacle  of  each  gland,  becomes  inflated,  and  this 
diftention  increafes,  till  by  its  very  great  ftimulus  inflammation  is 
produced,  or  till  thofe  parts  of  the  vifcus  become  totally  para- 
lytic. This  difeafe  is  diftinguifhable  from  the  foregoing  by  the 
palpable  hardnefs  or  largenefs  of  the  liver;  and  as  the  hepatic 
glands  are  not  totally  paralytic,  or  the  whole  liver  not  affefted, 
fome  bile  continues  to  be  made.  The  inflammations  of  this 
vifcus,  confequent  to  the  fcirrhofity  of  it,  belong  to  the  difeafes 
of  the  fenfitive  motions,  and  will  be  treated  of  hereafter. 

6.  The  ancients  are  faid  to  have  poflefied  an  art  of  increafing 
the  livers  of  geefe  to  a  fize  greater  than  the  remainder  of  the 
goofe.  Martial.  1.  13.  epig.  58. — This  is  faid  to  have  been  done 
by  fat  and  figs.  Horace.  1.  2.  fat.  8. — Juvenal  fets  thefe  large 
livers  before  an  epicure  as  a  great  rarity.  Sat.  5.  1.  114;  and 
Perfius,  fat.  6.  1.  71.  Pliny  fays  thefe  large  goofe-livers  were 
foaked  in  mulled  milk,  that  is,  I  fuppofe  milk  mixed  with  honey 
and  wine  ;  and  adds,  "  that  it  is  uncertain  whether  Scipio 
Metellus,  of  confular  dignity,  or  M.  Seftius,  a  Roman  knight, 
was  the  great  difcoverer  of  this  excellent  di(h."  A  modern 
traveller,  I  believe  Mr.  Brydone,  aflerts  that  the  art  of  enlarging 
the  livers  of  geefe  ftill  exiits  in  Sicily  ;  and  it  is  to  be  lamented 
that  he  did  not  import  it  into  his  native  county,  as  fome  method 
of  affe&ing  the  human  liver  might  perhaps  have  been  collected 
from  it ;  befides  the  honor  he  might  have  acquired  in  improving 
our  giblet  pies. 

Our  wifer  caupones,  I  am  told,  know  how  to  fatten  their 
fowls,  as  well  as  their  geefe,  for  the  London  markets,  by  mix- 
ing gin,  inftead  of  figs  and  fat  with  their  food  ;  by  fohich  they 
are  faid  to  become  fleepy,  and  to  fatten  apace,  and  probably  ac- 
quire enlarged  livers  ;  as  the  fwine  are  aflerted  to  do,  which  arc 
fed  on  the  fediments  of  barrels  in  the  diflilleries ;  and  which  fo 
frequently  obtains  in  thofe,  who  ingurgitate  much  ale,  or  wine, 
or  drams. 

II.  The  irritative  difeafes  of  the  kidneys,  pancreas,  fpleen, 
and  other  glands,  are  analagous  to  thofe  of  the  liver  above  de- 
icribed,  differing  only  in  the  confequences  attending  their  ina- 
bility to  adlion.  For  inftance,  when  the  fecretory  veflels  of  the 
kidneys  become  difobedient  to  the  ftimulus  of  the  palling  cur- 
rent of  blood,  no  urine  is  feparated  or  produced  by  them  ;  their 
excretory  mouths  become  filled  with  concreted  mucus,  or  cal- 
culous  matter,  and  in  eight  or  ten  days  (tupor  and  death  fuper- 
vene  in  confequence  of  the  retention  of  the  feculent  part  of  the 
blood. 

This  difeafe  in  a  flighter  degree,  or  when  only  a  part  of  the 
kidney  is  affeded,  is  fucceeded  by  partial  inflammation  of  the 

kidney 


PARALYSIS,  &c.  SECT.  XXX.  3, 

kidney  in  confequence  of  previous  torpor.  In  that  cafe  greater 
adtions  of  the  fecretory  vefTels  occur,  and  the  nucleus  of  gravel 
Is  formed  by  the  inflamed  mucous  membranes  of  the  tubuli  uri- 
niferi,  as  farther  explained  in  its  place. 

This  torpor,  or  paralyfis  of  the  fecretory  ve  fiels  of  the  kid- 
*  iieys,  like  that  of  the  liver,  owes  its  origin  to  their  being  previ- 
oufly  habituated  to  too  great  ftimulus;  which  in  this  country 
is  generally  owing  to  the  alcohol  contained  in  ale  or  wine  ;  and 
hence  mult  be  regiftered  amongft  the  difeafes  owing  to  inebrie- 
ty 5  though  it  may  be  caufed  by  whatever  occcafionally  inflames 
the  kidney  ;  as  too  violent  riding  on  horfeback,  or  the  cold  from 
a  damp  bed,  or  by  fleeping  on  the  cold  ground  j  or  perhaps  by 
drinking  in  general  too  litile  aqueous  fluids. 

III.  I  mall  conclude  this  fedion  on  the  difeafes  of  the  liver 
induced  by  fpirituous  liquors,  with  the  well  known  ftory  of 
Prometheus,  which  feems  indeed  to  have  been  invented  by  phy- 
ficians  in  thofe  ancient  times,  when  all  things  were  clothed  in 
hieroglyphic,  or  in  fable.  Prometheus  was  painted  a*  dealing 
fire  from  heaven,  which  might  well  reprefent  the  inflammable 
fpirit  produced  by  fermentation  ;  which  may  be  faid  to  animate 
or  enliven  the  man  of  clay  :  whence  the  conquefts  of  Bacchus, 
as  well  as  the  temporary  mirth  and  noife  of  his  devotees.  But 
the  after  punifhment  of  thofe,  who  (teal  this  accurfed  fire,  is  a 
vulture  gnawing  the  liver  ;  and  well  allegorifes  the  poor  inebri- 
ate lingering  for  years  under  painful  hepatic  diieafes.  When 
the  expediency  of  laying  a  further  tax  on  the  diiiillation  of  fpir- 
ituous liquors  from  grain  was  canvafTed  before  the  Houfe  of 
Commons  fome  years  ago,  it  was  faid  of  the  diftillers,  with  great 
truth,  "  They  take  the  bread  from  the  people,  a$d  convert  it  into 
poifon  P"  Yet  is  this  manufactory  of  difeafe  permitted  to  con- 
tinue, as  appears  by  its  paying  into  the  treafury  above  900,000^ 
near  a  million  of  money  annually*  And  thus,  under  the  names 
of  rum,  brandy,  gin,  whifky,  ufquebaugh,  wine,  cider,  beer,  and 
porter,  alcohol  is  become  the  bane  of  the  Chriftian  world,  a% 
opium  of  the  Mahometan. 

Evoe  !  parce,  JLiber, 
Parce,  gravi  metuende  thyrfo  \ 


SECT. 


SECT.  XXXI.  i.      OF  TEMPERAMENTS.  277 


SECT.      XXXL 

OF    TEMPERAMENTS. 

L  The  temperament  of  decreafed  irritability  known  by  weak 

large  pupils  of  'the  eye '/,  cold  extremities.  Are  generally  fuppofed 
to  be  too  irritable.  Bear  pain  better  than  labour.  Natives  of 
North- America  contra  fled  with  thofe  upon  the  coaft  of  Africa. 
Narrow  and  broad Jhouldered  peoplea  Irritable  conftitutions  bear 
labour  better  than  pain.  II.  Temperament  of  increafedfenfibility. 
Liable  to  intoxication ,  to  inflammation^  hamoptoe,  gutta  ferena^  en- 
thufiafm,  delirium ,  reverie  Thefe  conftitutions  are  indolent  to 
voluntary  exertions ',  and  dull  to  irritations.  The  natives  of  South- 
America^  and  brute  animals  of  this  temperament.  III.  Of  in- 
creafed  voluntarity  ;  thefe  are  fubjetl  to  locked  jawy  convulfions^ 
epilepfy^  mania*  Are  very  active^  bear  coldy  hunger^  fatigue. 
Are  fuited  to  great  exertions.  This  temperament  dijlinguifoes 
mankind  from  other  animals.  IV.  Of  increafed  affbciation. 
Thefe  have  great  memories^  are  liable  to  quartan  agues>  and 
Jironger  fympathies  of  parts  with  each  other.  V.  Change  of 
temperaments  into  one  another. 

ANCIENT  writers  have  fpoken  much  of  temperaments,  but 
without  fufficient  precifion.  By  temperament  of  the  fyftem 
fhould  be  meant  a  permanent  prediipofition  to  certain  dalles  of 
dileafes  :  without  this  definition  a  temporary  predifpofition  to 
every  diftinft  malady  might  be  termed  a  temperament.  There 
are  four  kinds  of  conititurion,  which  permanently  deviate  from 
good  health,  and  are  perhaps  fufficiently  marked  to  be  diftin- 
guilhed  from  each  other,  and  conftitute  the  temperaments  or 
predifpofitions  to  the  irritative,  fenfitive,  voluntary,  and  afToci- 
ate  claries  of  difeafes. 

I.  The  Temperament  of  decreafed  Irritability. 

THE  difeafes,  which  are  caufed  by  irritation,  mod  frequently 
originate  from  the  defeft  of  it ;  for  thofe,  which  are  immedi- 
ately owing  to  theexcefsof  it,  as  the  hot  fits  of  fever,are gener- 
ally occafioned  by  an  accumulation  of  fenforial  power  in  confe- 
quence  of  a  previous  defe£l  of  irritation,  as  in  the  preceding 
cold  fits  of  fever.  Whereas  the  difeaies,  which  are  caufed  by 
fenfation  and  volition,  moft  frequently  originate  from  the  excefs 
q»f  thofe  fenforial  powers,  as  will  be  explained  below. 

The  temperament  of  decreafed  irritability  appears  from  the 

following 


278  OF  TEMPERAMENTS.      SECT.  XXXI.  i. 

following  circumftances,  which  fhew  that  the  mufcular  fibres 
or  organs  of  fenfe  are  liable  to  become  torpid  or  quiefcent  from 
lefs  defect  of  ftimulation  than  is  productive  of  torpor  or  quief- 
cence  in  other  conftitutions. 

i.  The  firft  is  the  weak  pulfe,  which  in  fome  coftitutions 
is  at  the  fame  time  quick.  2.  The  next  moft  marked  criterion 
of  this  temperament  is  the  largenefs  of  the  aperture  of  the  iris, 
or  pupil  of  the  eye,  which  has  been  reckoned  by  fome  a  beauti- 
ful feature  in  the  female  countenance,  as  an  indication  of  deli- 
cacy, but  to  an  experienced  obferver  it  is  an  indication  of  de- 
bility, and  is  therefore  a  defect,  not  an  excellence.  The  third 
moft  marked  circumftance  in  this  conftiturion  is,  that  the  ex- 
tremities, as  the  hands  and  feet,  or  nofe  and  ears,  are  liable  to 
beccome  cold  and  pale  in  fituations  in  refpett  to  warmth,  where 
thofe  of  greater  ftrength  are  not  affected.  Thofe  of  this  tem- 
perament are  fubjctl  to  hyfteric  affections,  nervous  fevers,  hy- 
drocephaius,  fcroiula,  and  confumption,  and  to  all  other  difeafes 
of  debility. 

Thofe,  who  pofTefs  this  kind  of  conftitution,  are  popularly 
fuppofed  to  be  more  irritable  than  is  natural,  but  are  in  reality 
lefs  fo.  This  miftake  has  arifen  from  their  generally  having  a 
greater  quicknefs  of  pulfe,  as  explained  in  Seel.  XII.  i.  4.  XII. 
3.3;  but  this  frequency  of  pulfe  is  not  necefiary  to  the  temper- 
ament, like  the  debility  of  it. 

Perfons  of  this  temperament  are  frequently  found  amongft 
the  fofter  fex,  and  amongft  narrow  {houldered  men  ;  who  are 
faid  to  bear  labour  worfe,  and  pain  better  than  others.  This 
laft  circumftance  is  fuppofed  to  have  prevented  the  natives  of 
North-America  from  having  been  made  flaves  by  the  Europeans. 
They  are  a  narrow- fliouldered  race  of  people,  and  will  rather 
expire  under  the  lafh,  than  be  made  to  labour.  Some  nations 
of  Afia  have  fmall  hands,  as  may  be  feen  by  the  handles  of  their 
fcymetars  ;  which  with  their  narrow  (houlders  fhew,  that  they 
have  not  been  accuftomed  to  fo  great  labour  with  their  hands 
and  arms,  as  the  European  nations  in  agriculture,  and  thofe  on 
the  coafts  of  Africa  in  fwimming  and  rowing.  Dr.  Manning- 
ham,  a  popular  accoucheur  in  the  beginning  of  this  century, 
obferves  in  his  aphorifms,  that  broad-fhouldered  men  procreate 
broad  {houldered  children.  Now  as  labour  ftrengthens  the 
mufcles  employed,  and  increafes  their  bulk,  it  woud  feem  that 
a  few  generations  of  labour  or  of  indolence  may  in  this  refpect 
change  the  form  and  temperament  of  the  body. 

On  the  contrary,  thofe  who  are  happily  poflefled  of  a  great  de- 
gree of  irritability,  bear  labour  better  than  pain ;  and  are  ftrong, 
adive,  and  ingenious.  But  there  is  not  properly  a  temperament 

of 


SECT.  XXXI  i.       OF  TEMPERAMENTS.  279 

of  increafed  irritability  tending  to  difeafe,  becaufe  an  increafed 
quantity  of  irritative  motions  generally  induces  an  increafe  of 
pleafureor  pain,  as  intoxication,  or  inflammation  ;  and  then 
the  new  motions  are  the  immediate  confequences  of  increafed 
fenfation,  not  of  increafed  irritation  ;  which  have  hence  been 
fo  perpetually  confounded  with  each  other. 


II.   Temperament  of  Senftbility. 

THER,E  is  not  properly  a  temperament,  or  a  predifpofition  to 
difeafe,  from  decreafed  fenfibility,  fmce  irritability  and  not  fenfi- 
bility  is  immediately  necefiary  to  bodily  health.  Hence  it  is  the 
excefs  of  fenfation  alone,  as  it  is  the  defect  of  irritation,  that  moft 
frequently  produces  difeafe.  This  temperament  of  increafed  fen- 
fibility is  known  from  the  increafed  aftivify  of  all  thofe  motions 
of  the  organs  of  fenfe  and  mufcles,  which  are  exerted  in  confe- 
quence  of  pleafure  or  pain,  as  in  the  beginning  of  drunkennefs, 
and  in  inflammatory  fever.  Hence  thofe  of  this  conflitution 
are  liable  to  inflammatory  difeafes,  as  hepatitis  ;  and  to  that 
kind  of  confumption  which  is  hereditary,  and  commences  with 
flight  repeated  hsemoptoe.  They  have  high-coloured  lips,  fre- 
quently dark  hair  and  dark  eyes  with  large  pupils,  and  are  in 
that  cafe  fubje£t  to  gutta  ferena.  They  are  liable  to  enthufiafm, 
delirium,  and  reverie.  In  this  lad  circumftance  they  are  liable 
to  (tart  at  the  clapping  of  a  door  ;  becaufe  the  more  intent  any 
one  is  on  the  paffing  current  of  his  ideas,  the  greater  furprife  he, 
experiences  on  their  being  diflevered  by  fome  external  violence, 
as  explained  in  Se6t.  XIX.  on  reverie. 

As  in  thefe  conftitutions  more  than  the  natural  quantities  of 
fenfitive  motions  are  produced  by  the  increafed  quantity  of  fen- 
fation exifting  in  the  habit,  it  follows,  that  the  irritative  motions 
will  be  performed  in  fome  degree  with  lefs  energy,  owing  to  the 
great  expenditure  of  fenforial  power  on  the  fenfitive  ones. 
Hence  thofe  of  this  temperament  do  not  attend  to  flight  flimu- 
lations,  as  explained  in  Sedt.  XIX.  But  when  a  ftimulus  is  fo 
great  as  to  excite  fenfation,  it  produces  greater  fenfitive  actions 
of  the  fyftem  than  in  others  :  fuch  as  delirium  or  inflammmation. 
Hence  they  are  liable  to  be  abfent  in  company  ;  fit  or  lie  long 
in  one  pofture  ;  and  in  winter  have  the  Ikin  of  their  legs  burnt 
into  various  colours  by  the  fire.  Hence  alfo  they  are  fearful  of 
pain  ;  cover  mufic  and  fleep  ;  and  delight  in  poetry  and  romance. 

As  the  motions  in  confequence  of  fenfation  are  more  than  nat- 
ural, it  aifo  happens  from  the  greater  expenditure  of  fenforial 
power  on  them,  that  the  voluntary  motions  are  lefseafily  exerted. 

Hence 


280  OF  TEMPERAMENTS.      SECT.  XXXI.  3, 

Hence  the  lubje&s  of  this  temperament  are  indolent  in  refpedl: 
to  all  voluntary  exertion,  whether  of  mind  or  body. 

A  race  of  people  of  this  description  feems  to  have  been  found 
by  the  Spaniards  in  the  iflands  of  America,  whuare  they  firft 
landed,  ten  of  whom  are  faid  not  to  have  confumed  more  food 
than  one  Spaniard,  nor  to  have  been  capable  of  more  than  one 
tenth  of  the  exertion  of  a  Spaniard.  Robert  fon's  Hiitory, — la 
a  date  fimilar  to  this  the  greated  part  of  the  animal  world  pafs 
their  lives,  between  fleep  and  inactive  reverie,  except  when  they 
are  excited  by  the  call  of  hunger. 

III.  The  Temperament  of  increafed  Voluntarily. 

THOSE  of  this  conditution  differ  from  both  the  laft  mentioned 
m  this,  that  the  pain,  which  gradually  fubfides  in  the  firft,  and 
is  produ&ive  of  inflammation  or  delirium  in  the  fecond,  is  in 
this  fucceeded  by  the  exertion  of  the  mufcles  or  ideas,  which 
are  mod  frequently  connected  with  volition  ;  and  they  are 
thence  fubject  to  locked  jaw,  convulfions,  epilepfy,  and  mania, 
as  explained  in  Sed~l.  XXXIV.  Thofe  of  this  temperament  at* 
tend  to  the  flighted  irritations  or  fenfations,  and  immediately  ex- 
ert themfelves  to  obtain  or  avoid  the  objects  of  them  ;  they  can 
at  the  fame  time  bear  cold  and  hunger  better  than  others,  of 
which  Charles  the  Twelfth  of  Sweden  was  an  indance.  They 
are  fuited  and  generally  prompted  to  all  great  exertions  of  genius 
or  labour,  as  their  defires  are  more  extenfive  and  more  vehe- 
ment, and  their  powers  of  attention  and  of  labour  greater.  It  is 
this  facility  of  voluntary  exertion,  which  didinguifhes  men  from 
brutes,  and  which  has  made  them  lords  of  the  creation. 

IV.  The  Temperament  of  increafed  djjociation. 

THIS  conditution  confids  in  the  too  great  facility,  with  which 
the  fibrous  motions  acquire  habits  of  afTociation,  and  by  which 
thefe  aflbciations  become  proporrionably  dronger  than  in  thofe 
of  the  other  temperaments.  Thofe  of  this  temperament  are  flow 
in  voluntary  exertions,  or  in  thofe  dependent  on  fenfation, 
or  on  irritation.  Hence  great  memories  have  been  faid  to  be 
t  attended  with  lefs  fenfe  and  lefs  imagination  from  Aridotlc 
down  to  the  prefent  time  ;  for  by  the  word  memory  thefe  writers 
only  underdood  the  unmeaning  repetition  of  words  or  numbers 
in  the  order  they  were  received,  without  any  voluntary  efforts 
of  the  mind. 

In  this  temperament  thofe  aflbciations  of  motions,  which  are 
commonly  termed  fympathies,  ac~t  with  greater  certainty  and 

energy, 


SECT.  XXXI.  5.       OF  TEMPERAMENTS.  281 

energy  as  thofe  between  diflurbed  vifion  and  the  inverfion  of 
the  motion  of  the  iiomach,  as  in  fea-fickneis  ;  and  the  pains  in 
the  fhouider  from  hepatic  inflammation.  Add  to  this,  that  the 
catenated  circles  of  actions  are  of  greater  extent  than  in  the  oth- 
er confutations.  Thus  if  a  ftrong  vomit  or  cathartic  be  exhibited 
in  this  temperament,  a  fmaller  quantity  will  produce  as  great 
an  eflecl:,  if  it  be  given  fome  weeks  afterwards  ;  whereas  in  other 
temperaments  this  is  only  to  be  expected,  if  it  be  exhibited  in  a 
few  days  after  the  firft  dofe.  Hence  quartan  agues  are  formed 
in  thofe  of  this  temperament,  as  explained  in  Section  XXXII. 
on  difeafes  from  irritation,  and  other  intermittents  are  liable  to 
recur  from  flight  caufes  many  weeks  after  they  have  been  cured 
by  the  bark. 

V.  The  firft  of  thefe  temperaments  differs  from  the  ftandard 
of  health  from  defect,  and  the  others  from  excefs  of  fenforial 
power  ;  but  it  fometimes  happens  that  the  fame  individual,  from 
the  changes  introduced  into  his  habit,  by  the  different  feafons  of 
the  year,  modes  or  periods  of  life,  or  by  accidental  difeafes, 
paffes  from  one  of  thefe  temperaments  to  another.  Thus  a  long 
ufe  of  too  much  fermented  liquor  produces  the  temperament  of 
increafed  fenfibility  ;  great  idolence  and  folitude  that  of  de- 
creafed  irritability  ;  and  want  of  the  neceffaries  of  Jife  that  of 
•afed  voluntarity. 


VOL.  I.  NN  SECT, 


28a  DISEASES  SECT.  XXXIL  i. 

SECT.      XXXIL 

DISEASES   OF    IRRITATION. 

I.  Irritative  fevers  with  Jlrong  pulfe.  With  weak  pulfe.  Symp- 
toms of  fever.  Their  four ce.  II.  I.  <j$uick  pulfe  is  owing  to 
deer eafed  irritability.  2.  Not  in  Jleep  or  in  apoplexy.  3  From 
inanition.  Owing  to  deficiency  of  fenforial  power.  III.  i.  Caufes 
of  fever.  From  def eft  of  heat.  Heat  from  fecretions..  Pain  of 
cold  in  the  loins  and  forehead,  2.  Great  expenfe  of fenforial  power 
in  the  vital  motions.  Immerfion  in  cold  water.  Succeeding  glow 
of  heat.  Difficult  refpiration  in  cold  bathing  explained.  Why 
the  cold  bath  invigorates.  Bracing  and  relaxation  are  mechanical 
terms.  3.  Ufes  of  cold  bathing.  Ufes  of  cold  air  in  J ever s.  4. 
Ague  Jits  from  cold  air.  Whence  their  periodical  returns.  IV. 
Defecl  of  difiention  a  caufe  of  fever.  Deficiency  of  blood.  Tranf- 
fufion  of  blood.  V.  i.  Defeft  of  momentum  of  the  blood  from  me- 
chanicfiimuli.  2.  Air  injecled  into  the  blood  vefle/s.  3.  Exer- 
cife  increafes  the  momentum  of  the  blood-  4.  Sometimes  bleeding 
increafes  the  momentum  of  it.  VL  Influence  of  the  fun  and  moon 
en  difeafes.  The  chemical  ftimulus  of  the  blood.  M.enjlruation 
obeys  the  lunations.  Queries.  VII.  ^uiefcence  of  large  glands 
a  caufe  of  fever.  -Swelling  of  the  pr&cordia.  VIII.  Other  caufe f 
of  quiefcence,  as  hunger,  bad  air,  fear,  anxiety.  IX.  I .  Symp- 
toms of  the  cold  fit.  2  Of  the  hot  fit.  3.  Second  cold  fit  why. 
4.  Inflammation  introduced,  or  delirium,  orfiupor,  Xi  Recap- 
itulation. Fever  not  an  effort  of  nature  to  relieve  h  erf  elf.  Doc* 
trine  of  fpafm. 

I.  WHEN  the  contraftile  fides  of  the  heart  and  arteries  per- 
form a  greater  number  of  pulfations  in  a  given  lime,  and  move 
through  a  greater  area  at  each  pulfation,  whether  thefe  motions 
are  occafioned  by  the  ftimulus  of  the  acrimony  or  quantity  of  the 
blood,  or  by  their  aflbciation  with  other  irritative  motions,  or  by 
the  increafed  irritability  of  the  arterial  fyftem,  that  is,  by  an  in- 
creafed  quantity  of  fenforial  power,  one  kind  of  fever  is  produ- 
ced ;  which  may  be  called  Synocha  irritativa,  or  Febris  irritativa 
pulfu  forti,  or  irritative  fever  with  ftrong  pulfe. 

When  the  contractile  fides  of  the  heart  and  arteries  perform 
a  greater  number  of  pulfations  in  a  given  time,  but  move  through 
a  much  lefs  area  at  each  pulfation,  whether  thefe  motions  are 
occafioned  by  defeat  of  their  natural  ftimuli,  or  by  the  defe£t  of 
other  irritative  motions  with  which  they  are  aflbciated,  or  from 
the  inirritability  of  the  arterial  fyftem,  that  is,  from  a  decreafed 

quantity 


SECT.  XXXII.  a.  i.       OF  IRRITATION.  283 

quantity  of  fenforial  power,  another  kind  of  fever  arifes;  which 
may  be  termed,  Typhus  irritativus,  or  Febris  irritativa  pulfu  de- 
bili,  or  irritative  fever  with  weak  pulfe.  The  former  of  thefe 
fevers  is  the  fynocha  of  nofologifts,  and  the  latter  the  typhus  mi- 
tior,  or  nervous  fever.  In  the  former  there  appears  to  be  an 
increafe  of  fenforial  power,  in  the  latter  a  deficiency  of  it ; 
which  is  fhewn  to  be  the  immediate  caufe  of  ftrength  and  weak- 
nefs,  as  defined  in  Seel.  XII.  1.3. 

It  mould  be  added,  that  a  temporary  quantity  of  ftrength  or 
debility  may  be  induced  by  the  defecl  or  excefs  of  (limulus  above 
what  is  natural  ;  and  that  in  the  fame  fever  debility  always  exifts 
during  the  cold  fa,  though  Jirength  does  not  a/ways  exijl  during  the 
hot  fit. 

Thefe  fevers  are  always  connefled  with,  and  generally  indu- 
ced by,  the  difordered  irritative  motions  of  the  organs  of  fenfe, 
or  of  the  inteftinal  canal,  or  of  the  glandular  fyftem,  or  of  the 
abforbent  fyftem  ;  and  hence  are  always  complicated  with  fome 
or  many  of  thefe  difordered  motions,  which  arc  termed  the  fymp- 
toms  of  the  fever,  and  which  compofe  the  great  variety  of  thefe 
difeafes. 

The  irritative  fevers  both  with  ftrong  and  wit  h  weak  pulfe, 
as  well  as  the  fenfitive  fevers  with  ftrong  and  with  weak  pulfe, 
which  are  to  be  defcribed  in  the  next  feclion,  are  liable  to  peri- 
odical remiffions,  and  then  they  take  the  name  of  intermittent 
fevers,  and  are  diftinguifhed  by  the  periodical  times  of  their 
accefs 

II.  For  the  better  illuftration  of  the  phenomena  of  irritative 
fevers,  we  muft  refer  the  reader  to  thecircumftancesof  irritation 
explained  in  Seel.  XII.  and  (hall  commence  this  intricate  fubjecl 
by  fpeaking  of  the  quick  pulfe,  and  proceed  by  confidering  many 
of  the  caufes,  which  either  feparately  or  in  combination  moft 
fequently  produce  the  cold  fits  of  fevers. 

ir  If  the  arteries  are  dilated  but  to  half  their  ufual  diameters, 
though  they  contract  twice  as  frequently  in  a  given  time,  they 
will  circulate  only  half  their  ufual  quantity  of  blood  :  for  as 
they  are  cylinders,  the  blood  which  they  contain  muft  be  as  the 
fquares  of  their  diameters.  Hence  when  the  pulfe  becomes 
quicker  and  fmaller  in  the  fame  proportion,  the  heart  and  arte- 
ries act  with  lefs  energy  than  in  their  natural  ftate.  See  Seel. 
XII.  i.  4. 

That  this  quick  fmall  pulfe  is  owing  to  want  of  irritability, 
appears  firft,  becaufe  it  attends  other  fymptoms  of  want  of  ir- 
ritability ;  and,  fecondly,  becaufe  on  the  application  of  a  ftimu- 
lus  greater  than  ufual,  it  becomes  flower  and  larger.  Thus  in 
cold  fits  of  agues,  in  hyfteric  palpitations  of  the  heart,  and  when 

the- 


234  DISEASES  SECT.  XXXIL  2.  2. 

the  body  is  much  exhaufted  by  haemorrhages,  or  by  fatigue,  as 
well  as  in  nervous  fevers,  the  pulfe  becomes  quick  and  imall  ; 
and  fecondly,  in  all  thofe  cafes  if  an  increafe  of  flimulus  be  ad- 
ded, by  giving  a  little  wine  or  opium  ;  the  quick  fmall  pulfe  be- 
comes flower  and  larger,  as  any  one  may  eaGly  experience  on 
himfelf,  by  counting  his  pulfe  after  drinking  one  or  two  glafTes 
of  wine,  when  he  is  faint  from  hunger  or  fatigue. 

Now  nothing  can  fo  ftrongly  evince  that  this  quick  fmali 
pulfe  is  owing  to  defe£t  of  irritability,  as  that  an  additional 
ftimulus,  above  what  is  natural,  makes  it  become  flower  arid 
larger  immediately  ;  for  what  is  meant  by  a  defect  of  irritabili- 
ty, but  that  the  arteries  and  heart  are  not  excited  into  their  ufual 
exertions  by  their  ufual  quantity  of  ftimulus?  but  if  you  increafe 
the  quantity  of  ftimulus  and  they  immediately  aft  with  rheir 
ufual  energy,  this  proves  their  previous  want  of  their  natural  de- 
gree of  irritability.  Thus  the  trembling  hands  of  drunkards  in 
a  morning  become  fteady,  and  acquire  iirength  to  perform  their 
ufual  offices,  by  the  accuftomed  ftimulus  of  a  glafs  or  two  of 
brandy. 

2.  In  deep  and  in  apoplexy  the  pulfe  becomes  flower,  which 
is  not  owing  to  defect  of  irritability,  for  it  is  at  the  fame  time 
larger  ;  and  thence  the  quantity  of  the  circulation  is  rather  in- 
creafed  than  diminifhed.  In  thefe  cafes  the  organs  of  fenfe  arc 
clofed,  and  the  voluntary  power  is  fufpended,  while  the  motions 
dependent  on  internal  irritations,  as  thofe  of  digeftion  and  fecre- 
tion,  are  carried  on  with  more  than  their  ufual  vigour  ;  which 
has  led  fuperficial  obfervers  to  confound  thefe  cafes  with  thofe 
arifing  from  want  of  irritability.  Thus  if  you  lift  up  the  eyelid 
of  an  apoplectic  patient,  who  is  not  actually  dying,  the  iris 
will,  as  ufual,  contract  itfelf,  as  this  motion  is  aflbciated  with 
the  ftimulus  of  light  ;  but  it  is  not  fo  in  the  laft  ftages  of  ner- 
vous fevers,  where  the  pupil  of  the  eye  continues  expanded  in 
the  broad  day  light  :  in  the  former  cafe  there  is  a  want,  of  volun- 
tary power,  in  the  latter  a  want  of  irritability. 

H  nee  alfo  thofe  conftitutions  which  are  deficient  in  quantity 
of  irritability,  and  which  poflefs  too  great  fenfibiiity,  as  during 
the  pain  of  hunger,  of  hyfteric  fpafrns,  or  nervous  headachs,  are 
generally  fuppofed  to  have  too  much  irritability  ;  and  opium, 
which  in  its  due  dofe  is  a  mod  powerful  ftimulant,  is  errone- 
oufly  called  a  fedative  ;  becaufe  by  increafing  the  irritative  mo- 
tions it  decreafes  the  pains  arifing  from  defect  of  them. 

Why  the  pulfe  (hould  become  quicker  both  from  an  increafe 
of  irrigation,  as  in  the  fynocha  irritativa,  or  irritative  fever  with 
itrong  pulfe;  and  from  the  decreafe  of  it,  as  in  the  typhus  irrita- 
tivus,  or  irritative  fever  with  weak  pulfe ;  feems  paradoxical* 

The 


SECT.  XXXII.  2-  3.       OF  IRRITATION.  285 

The  former  circumflance  needs  no  ill  uftration ;  fince  if  the  ftirnu- 
]  us  of  the  blood,  or  the  irritability  of  the  fanguiferous  fyftem  be 
mcreafed,  and  the  ftrength  of  the  patient  not  diminifhed,  it  is 
plain  that  the  motions  muft  be  performed  quicker  and  ftronger. 

In  the  latter  circumftance  the  weaknefs  of  the  mufcular  pow- 
er of  the  heart  is  foon  over- balanced  by  the  elafticity  of  the 
coats  of  the  arteries,  which  they  pofiefs  befides  a  muicular  power 
of  contraction  ;  and  hence  the  arteries  are  diftended  to  lefs  than 
their  ufual  diameters.  The  heart  being  thus  (topped,  when  at 
is  but  half  emptied,  begins  fooner  to  dilate  again  ;  and  the  ar- 
teries being  dilated  to  lefs  than  their  ufual  diameters,  begin  fo 
much  fooner  to  contract  themfelves  ;  infomuch,  that  in  the  laft 
fbges  of  fevers  with  weaknefs  the  frequency  of  pulfation  of  the 
heart  and  arteries  become  doubled  ;  which,  however,  is  never 
the  cafe  in  fevers  with  ftrength,  in  which  they  feldom  exceed 
1 1 8  or  1 20  pulfarions  in  a  minute.  It  muft  be  added,  that  in 
thefe  cafes,  while  the  pulfe  is  very  fmall  and  very  quick,  the- 
heart  often  feels  large,  and  labouring  to  one's  hand  •,  which  co- 
incides with  the  above  explanation,  (hewing  that  it  does  not 
completely  empty  itfelf. 

3.  In  cafes  however  of  debility  from  paucity  of  blood,  as  in 
animals  which  are  bleeding  to  death  in  the  flaughter-houfe,  the 
quick  pulfations  of  the  heart  and  arteries  may  be  owing  to  their 
not  being  diftended  to  more  than  half  their  ufual  diaftole  ;  and 
in  confequence  they  muft  contract  fooner,  or  more  frequently, 
in  a  given  time.  As  weak  people  are  liable  to  a  deficient  quan- 
tity of  blood,  this  caufe  may  occafionally  contribute  to  quicken 
the  pulfe  in  fevers  with  debility,  which  may  be  known  by  ap- 
plying one's  hand  upon  the  heart  as  above  ;  but  the  principal 
caufe  I  fuppofe  to  confift  in  the  diminution  of  fenforial  power. 
When  a  mufcle  contains,  or  is  fupplied  with  but  little  fenforiai 
power,  its  contraction  foon  ceafes,  and  in  confequence  may  foon 
recur,  as  is  feen  in  the  trembling  hands  of  people  weakened  by 
age  or  by  drunkennefs.  See  Seel.  XII.  i  4  XII.  3.  4, 

It  may  neverthelefs  frequently  happen,  that  both  the  deficiency 
of  ftimulus,  as  where  the  quantity  of  blood  is  lefiened  (as  de- 
fcribed  in  No.  4.  of  this  feclion),  and  the  deficiency  of  fenforiai 
power,  as  in  thofe  of  the  temperament  of  inirritability,  defcribed 
in  Se6t  XKXI.  occur  at  the  fame  time  ;  which  will  thus  add 
to  the  quicknefs  of  the  pulfe  and  to  the  danger  of  the  difeafe. 

III.  i .  A  certain  degree  of  heat  is  neceflary  to  mufcular  mo- 
tion, -and  is,  in  cor.fequence,  efiential  to  life.  This  is  obferved 
in  thofe  animals  and  infetls  which  pafs  the  cold  feafon  in  a  tor- 
pid (late,  and  which  revive  on  being  warmed  by  the  fire.  This 
n.  eceffcry  ftimulus  of  heat  has  two  fources ;  one  from  the  fluid 

atmofphere 


286  DISEASES  SECT.  XXXII.  3.  2. 

atmofphere  of  heat,  in  which  all  things  are  immerfed,  and  the 
other  from  the  internal  combinations  of  the  particles,  which 
form  the  various  fluids,  which  are  produced  in  the  extenfive 
fyftems  of  the  glands.  When  either  the  external  heat,  which 
furrounds  us,  or  the  internal  production  of  it,  becomes  leflened 
to  a  certain  degree,  the  pain  of  cold  is  perceived. 

This  pain  of  cold  is  experienced  moft  fenfibly  by  our  teeth, 
when  ice  is  held  in  the  mouth  ;  or  by  our  whole  fyftem  after 
having  been  previoufly  accuflomed  to  much  warmth.  It  is 
probable,  that  this  pain  does  not  arife  from  the  mechanical  or 
chemical  effects  of  a  deficiency  of  heat  ;  but  that,  like  the  or- 
gans of  fenfe  by  which  we  perceive  hunger  and  thirft,  this  fenfe 
of  heat  fuffers  pain,  when  the  ftimulus  of  its  objeft  is  wanting 
to  excite  the  irritative  motions  of  the  organ  ;  that  is,  when  the 
fenforial  power  becomes  too  much  accumulated  in  the  quiefcent 
fibres.  See  Sect.  XII.  53.  For  vas  the  periftaltic  mottbns  of 
the  ftomach  are  leflened,  when  the  pain  of  hunger  is  great,  fo 
the  action  of  the  cutaneous  capillaries  are  leflened  during  the 
pain  of  cold  ;  as  appears  by  the  paienefs  of  the  fkin,  as  explain- 
ed in  Seel:.  XIV.  6.  on  the  production  of  ideas. 

The  pain  in  the  fmall  of  the  back  and  forehead  in  the  cold 
fits  of  the  ague,  in  nervous  hemicrania,  and  in  hyfteric  parox- 
yfms,  when  all  the  irritative  motions  are  much  impaired,  feems 
to  arife  from  this  caufe  :  the  veflels  of  thefe  membranes  or 
mufcles  become  torpid  by  their  irritative  aflbciations  with  other 
parts  of  the  body,  and  thence  produce  lefs  of  their  accuftomed 
fecretions,  and  in  confequence  lefs  heat  is  evolved,  and  they 
experience  the  pain  of  cold  ;  which  coldnefs  may  often  be  felt 
by  the  hand  applied  upon  the  afFe&ed  part. 

2.  The  importance  of  a  greater  or  lefs  dedu&ion  of  heat 
from  the  fyftem  will  be  more  eafy  to  comprehend,  if  we  firft 
confider  the  great  expenfe  of  fenforial  power  ufed  in  carrying 
on  the  vital  motions  •,  that  is,  which  circulates,  abforbs,  fecretes, 
aerates,  and  elaborates  the  whole  mafs  of  fluids  with  unceafing 
afliduity.  The  fenforial  power,  or  fpirit  of  animation,  ufed  in 
giving  perpetual  and  ftrong  motion  to  the  heart,  which  over- 
comes the  elafticity  and  vis  inertix  of  the  whole  arterial  fyftem  ; 
next  the  expenfe  of  fenforial  power  in  moving  with  great  force 
and  velocity  the  innumerable  trunks  and  ramifications  of  the 
arterial  fyftem  ;  the  expenfe  of  fenforial  power  in  circulating 
the  whole  mafs  of  blood  through  the  long  and  intricate  intor- 
tions  of  the  very  fine  veflels,  which  compofe  the  glands  and 
capillaries  ;  then  the  expenfe  of  fenforial  power  in  the  exer- 
tions of  the  abforbent  extremities  of  all  the  la&eals,  and  of  all 
the  lymphatics,  which  open  their  mouths  on  the  external  fur- 
face 


SECT.  XXXII.  3.  2.    OF  IRRITATION.  287 

face  of  the  ikin,  and  on  the  internal  furfaces  of  every  cell  or 
interftice  of  the  body  ;  then  the  expenfe  of  fenforial  power  in 
the  venous  abforption,  by  which  the  blood  is  received  from  the 
capillary  veflels,  or  glands,  where  the  arterial  power  ceafes,  and 
is  drunk  up,  and  returned  to  the  heart ;  next  the  expenfe  of 
fenforial  power  ufed  by  the  mufcles  of  refpiration  in  their  of- 
fice of  perpetually  expanding  the  bronchia,  or  air-veflels,  of  the 
lungs;  and  laftly  in  the  unceafmg  periftaltic  motions  of  the 
ftomach  and  whole  fyftem  of  inteftines,  and  in  all  the  fecre- 
tions  of  bile,  gaftric  juice,  mucus,  perfpirable  matter,  and  the 
various  excretions  from  the  fyftem.  If  we  confider  the  ceafe- 
lefs  expenfe  of  fenforial  power  thus  perpetually  employed,  it 
will  appear  to  be  much  greater  in  a  day  than  all  the  voluntary 
exertions  of  our  mufcles  and  organs  of  fenfe  confume  in  a 
week  ;  and  all  this  without  any  fenfible  fatigue  !  Now,  if  but 
a  part  of  thefe  vital  motions  are  impeded,  or  totally  (lopped  for 
but  a  (hort  time,  we  gain  an  idea  that  there  muft  be  a  great  ac- 
cumulation of  fenforial  power  ;  as  its  production  in  thefe  or- 
gans, which  are  fubjedt  to  perpetual  a£tivity,  is  continued  dur- 
ing their  quiefcence,  and  is  in  confequence  accumulated. 

While,  on  the  contrary,  where  thofe  vital  organs  adt  too  for- 
cibly by  increafe  of  ftimulus  without  a  proportionally  increafed 
production  of  fenforial  power  in  the  brain,  it  is  evident,  that  a 
great  deficiency  of  adlion,  that  is  torpor,  muft  foon  follow,  as 
in  fevers  ;  whereas  the  locomotive  mufcles,  which  aft  only  by 
intervals,  are  neither  liable  to  fo  great  accumulation  of  fenforial 
power  during  their  times  of  inactivity,  nor  to  fo  great  an  ex- 
hauftion  of  it  during  their  times  of  a£tion. 

Thus,  on  going  into  a  very  cold  bath,  fuppofe  at  33  degrees 
of  heat  on  Fahrenheit's  fcale,  the  adion  of  the  fubcutaneous 
capillaries,  or  glands,  and  of  the  mouths  of  the  cutaneous  ab- 
forbents  is  diminifhed,  or  ceafes  for  a  time.  Hence  lefs  or  no 
blood  pafles  thefe  capillaries,  and  paienefs  fucceeds.  But  foon 
after  emerging  from  the  bath,  a  more  florid  colour  and  a  greater 
degree  of  heat  are  generated  on  the  (kin  than  was  pofleffcd  be- 
fore immerfion  ;  for  the  capillary  glands,  after  this  quiefcent 
ftate,  occafioned  by  the  want  of  ftimulus,  become  more  irritable 
than  ufual  to  their  natural  ftimuli,  owing  to  the  accumulation  of 
fenforial  power,  and  hence  a  greater  quantity  of  blood  is  tranf- 
mitted  through  them,  and  a  greater  fecretion  of  perfpirable 
matter  ;  and,  in  confequence,  a  greater  degree  of  heat  fucceeds. 
During  the  continuance  in  cold  water  the  breath  is  cold,  and 
the  a£t  of  refpiration  quick  and  laborious  ;  which  have  gener- 
ally been  afcribed  to  the  obflruftion  of  the  circulating  fluid  by 
a  fpafm  of  the  cutaneous  veflels,  and  by  a  confequent  accumu- 
lation 


288  DISEASES  SECT.  XXXII.  3. 3, 

lation  of  blood  in  the  lungs,  occafioned  by  the  preflure  as  well 
as  by  the  -oldnefs  of  the  water.  This  is  not  a  fatisfaftory  ac- 
count of  this  curious  phenomenon,  fince  at  this  time  the 
whole  circulation  is  lefs,  as  appears  from  ihe  fmallnefs  of  the 
pulfe  and  colclnefs  of  the  breath  ;  which  {hew  that  lefs  blood 
pafTes  through  the  lungs  in  a  given  time  ;  the  fame  laborious 
breathing  immediately  occurs  when  the  palenefs  of  the  fkin  is 
produced  by  fear,  where  no  external  cold  or  preflure  are  applied. 

The  minute  veflels  of  the  bronchia,  through  which  the  blood 
pafles  from  the  arterial  to  the  venal  fyltem,  and  which  corref- 
pond  with  the  cutaneous  capillaries,  have  frequently  been  ex- 
pofed  to  cold  air,  and  become  quiefcent  along  with  thofe  of  the 
Ikin ;  and  hence  their  motions  are  fo  aflbciated  together,  that 
when  one  is  affected  either  with  quiefcence  or  exertion,  the 
other  fympathizes  with  it,  according  to  the  laws  of  irritative 
ailbciation.  See  Sect-  XXVII.  I.  on  haemorrhages. 

Befides  the  quiefcence  of  the  minute  veffcls  of  the  lungs, 
there  are  many  other  fyftems  of  veflels  which  become  torpid 
from  their  irritative  afibciations  with  thofe  of  the  Ikin,  as  the 
abforbents  of  the  bladder  and  inteftines  ;  whence  an  evacution 
of  pale  urine  occurs,  when  the  naked  fkin  is  expofed  only  to 
the  coldnefs  of  the  atmofphere  ;  and  iprinkling  the  naked  body 
with  cold  water  is  known  to  remove  even  pertinacious  confti- 
pation  of  the  bowels.  From  the  quiefcence  of  fuch  extenfive 
iyftems  of  veflels  as  the  glands  and  capillaries  of  the  fkin,  and 
the  minute  veflels  of  the  lungs,  with  their  various  abforbent  fe- 
ries  of  vefiels,  a  great  accumulation  of  fenforial  powers  is  occa- 
fioned  ;  part  of  which  is  again  expended  in  the  increafed  ex- 
ertion of  all  thefe  veflels,  with  an  univerfal  glow  of  heat  in  con- 
fequence  of  this  exertion,  and  the  remainder  of  it  adds  vigour 
to  both  the  vital  and  voluntary  exertions  of  the  whole  day. 

If  the  activity  of  the  fubcutaneous  veflels,  and  of  thofe  with 
which  their  actions  are  aflbciated,  was  too  great  before  cold  im- 
merfion,  as  in  the  hot  days  of  fummer,  and  by  that  means  the 
fenforial  power  was  previoufly  diminifhed,  we  fee  the  caufe 
why  the  cold  bath  gives  fuch  prefent  (trength  ;  namely,  by  {top- 
ping the  unncceflary  activity  of  the  iubcutaneous  veflels,  and 
thus  preventing  the  too  great  exhauftion  of  fenforial  power  ; 
which,  in  metaphorical  language,  has  been  called  bracing  the 
fyftem  :  which  is,  however,  a  mechanical  term,  only  applicable 
to  drums,  or  mufical  ftrings  :  as  on  the  contrary  the  word  re- 
laxation, when  applied  to  living  animal  bodies,  can  only  mean 
too  fmall  a  quantity  of  ftimulus,  or  too  fmall  a  quantity  of 
fenforial  power  ;  as  explained  in  Sect.  XII.  i. 

3.  This  experiment  of  cold  bathing  prefents  us  with  a  fimplc 

fever-  fit  > ; 


SECT.  XXXIL  3.  4.      OF  IRRITATION.  289 

fever-fit ;  for  the  pulfe  is  weak,  fmall,  and  quick  during  the 
cold  immerfion  ;  and  becomes  itrong,  full,  and  quick  during 
the  fubfequent  glow  of  heat ;  till  in  a  few  minutes  thefe  fymp- 
toms  fubfide,  and  the  temporary  fever  ceafes. 

In  thofe  conftitutions  where  the  degree  of  inirritability,  or  of 
debility,  is  greater  than  natural,  the  coldnefs  and  palenefs  of 
the  fkin  with  the  quick  and  weak  pulfe  continue  a  long  time 
after  the  patient  leaves  the  bath  ;  and  the  fubfequent  heat  ap- 
proaches by  unequal  flufliings,  and  he  feels  himfelf  difordered 
for  many  hours.  Hence  the  bathing  in  a  cold  fpring  of  water, 
where  the  heat  is  but  forty  eight  degrees  on  Fahrenheit's  ther- 
mometer, much  difagrees  with  thofe  of  weak  or  inirritable  hab- 
its of  body  ;  who  poflels  fo  little  fenforial  power,  that  they 
cannot  without  injury  bear  to  have  it  diminiihed  even  for  a 
fhort  time  ;  but  who  can  neverthelefs  bear  the  more  temperate 
coldnefs  of  Buxton  bath,  which  is  about  eighty  degrees  of  heat, 
and  which  ftrengthens  them,  and  makes  them  by  habit  lefs  lia- 
ble to  great  quiefcence  from  fmall  variations  of  cold  ;  and  thence 
lefs  liable  to  be  difordered  by  the  unavoidable  accidents  of  life. 
Hence  it  appears,  why  people  of  thefe  inirritable  conftitutions, 
which  is  another  expreflion  for  fenforial  deficiency,  are  often 
much  injured  by  bathing  in  a  cold  fpring  of  water  ;  and  why 
they  mould  continue  but  a  very  ftiort  time  in  baths,  which  are 
colder  than  their  bodies  ;  and  mould  gradually  increafe  both 
the  degree  of  the  coldnefs  of  the  water,  and  the  time  of  their 
continuance  in  it,  if  they  would  obtain  falutary  effects  from  cold 
immerfions.  See  Seel.  XIL  2.  i. 

On  the  other  hand,  in  all  cafes  where  the  heat  of  the  exter- 
nal furface  of  the  body,  or  of  the  internal  fuvface  of  the  lungs, 
is  greater  than  natural,  the  ufe  of  expofure  to  'cool  air  may  be 
deduced.  In  fever  fits  attended  with  ftrength,  that  is  with 
great  quantity  of  fenforial  power,  it  removes  the  additional  ftim- 
ulus  of  heat  from  the  furfaces  above  mentioned,  and  thus  pre- 
vents their  excefs  of  ufelefs  motion  ;  and  in  fever  fits  attended 
with  debility,  that  is  with  a  deficiency  of  the  quantity  of  fenfo- 
rial power,  it  prevents  the  great  and  dangerous  wafte  of  fenfo- 
rial power  expended  in  the  unnecefTary  increafe  of  the  actions 
of  the  glands  and  capillaries  of  the  ikin  and  lungs. 

4.  In  the  fame  manner  when  any  one  is  long  expofed  to 
very  cold  air,  a  quiefcence  is  produced  of  the  cutaneous  and 
pulmonary  capillaries  and  abforbents,  owing  to  the  deficiency 
of  their  ufual  llimulus  of  hear ;  and  this  quiefcence  of  fo  great 
a  quantity  of  veifels  affects,  by  irritative  aflbciation,  the  whole 
abforbent  and  glandular  fyftem,  which  becomes  in  a  greater  or 
*cfs  degree  quiefcent,  and  a  cold  fit  of  fever  is  produced. 

.  I.  o  o  K 


290  DISEASES  SECT.  XXXII.  4.  i. 

If  the  deficiency  of  the  ftimulus  of  heat  is  very  great,  the  qui- 
efcence  becomes  fo  general  as  to  extinguiQi  life,  as  in  thofe  who 
are  frozen  to  death. 

If  the  deficiency  of  heat  be  in  lefs  degree,  but  y-et  fo  great  as 
in  fome  meafure  to  diforder  the  fyftem,  and  (hould  occur  the 
facceeding  day,  it  will  induce  a  greater  degree  of  quiefcence 
than  before  from  its  acting  in  concurrence  with  the  period  of 
the  diurnal  circle  of  actions,  explained  in  Seel:  XXXVI  Hence 
from  a  fmall  beginning  a  greater  and  greater  degree  of  quief- 
cence may  be  induced,  till  a  complete  fever-fit  is  formed;  and 
which  will  continue  to  recur  at  the  periods  by  wliich  it  was 
produced.  See  Sett.  XVII.  3.  6. 

If  the  degree  of  quiefcence  occafioned  by  defecT:  of  the  ftimu- 
lus of  heat  be  very  great,  it  will  recur  a  fecond  time  by  a  flight-* 
er  caufe,  than  that  which  firft  induced  it.  If  the  caufe,  which 
induces  the  fecond  fit  of  quiefcence,  recurs  the  fucceeding  day, 
the  quotidian  fever  is  produced  ;  if  not  till  the  alternate  day,  the 
tertian  fever  ;  and  if  not  till  after  feventy-two  hours  from  the 
fir  It  fit  of  quiefcence,  the  quartan  fever  is  formed.  This  lait 
kind  of  fever  recurs  lefs  frequently  than  the  other,  as  it  is  adif- 
eafe  only  of  thofe  of  the  temperament  of  aflbciability,  as  men- 
tioned in  Seel.  XXXI.  ;  for  in  other  constitutions  the  capability 
of  forming  a  habit  ceafes,  before  the  new  caufe  of  quiefcence  is 
again  applied,  if  that  does  not  occur  fooner  than  in  feventy-two 
hours. 

And  hence  thofe  fevers,  whofe  caufe  is  from  cold  air  of  the 
night  or  morning,  are  more  liable  to  obferve  the  folar  day  in 
their  periods  ;  while  thofe  from  other  caufes  frequently  obferve 
the  lunar  day  in  their  periods,  their  paroxyfms  returning  near  an 
hour  later  every  day,  as  explained  in  Se£t.  XXXVI 

IV.  Another  frequent  caufe  of  the  cold  fits  of  fever  is  the 
defect  of  the  ftimulus  of  diflention.  The  whole  arterial  fyftem 
would  appear  by  the  experiments  of  Haller,  to  be  irritable  by 
no  other  ftimulus,  and  the  motions  of  the  heart  and  alimentary 
canal  are  certainly  in  fome  meafure  dependent  on  the  lame  caufe. 
See  Seel:.  XIV.  7.  Hence  there  can  be  no  wonder,  that  the 
diminution  of  diftention,  fhould  frequently  induce  the  quief- 
cence, which  conftitutes  the  beginning  of  fev:r  fits. 

Monfieur  Lieutaud  has  judicioully  mentioned  the  deficiency 
of  the  quantity  of  blood  amongft  the  caufes  of  difeafes,  which 
he  fays  is  frequently  evident  in  difledions ;  fevers  are  hence 
brought  on  by  great  hemorrhages,  diarrhoeas,  or  other  evacua- 
tions^; or  from  the  continued  uie  of  diet,  which  contains  but 
little  nourifhment  ;  or  from  the  exhauftion  occafioned  by  vio- 
lent fatigue,  or  by  thofe  chronic  difeafes  in  which  the  digeftion 

*  is 


SECT.  XXXII.  5.  i.      OF  IRRITATION.  i9i 

is  much  impaired  ;  as  where  the  ftomach  has  been  long  affecled 
with  the  gout  or  fcirrhus  ;  or  in  the  paralyfis  of  the  liver,  as  de- 
fcribed  in  Sect.  XXX  Hence  a  paroxyfrn  of  gout  is  liable  to 
recur  on  bleeding  or  purging  ;  as  the  torpor  of  forne  vifcns, 
which  precedes  the  inflammation  of  the  foot,  is  thus  induced  by 
the  want  of  the  ftimulus  of  diftemion.  And  hence  the  extremi- 
ties of  the  body,  as  the  nofe  and  ringers,  are  more  liable  to  be- 
come cold  when  we  have  long  abftained  from  food  •,  and  hence 
the  pulfe  is  increafed  both  in  ftrength  and  velocity  above  the 
natural  ftandard  after  a  full  meal  by  the  ftimulus  of  diftention. 

However,  this  ftimulus  of  diftention,  like  the  itimulus  of  heat 
above  described,  though  it  contributes  much  to  the  due  aftiori 
not  only  of  the  heart,  arteries,  and  alimentary  canal,  but  feems 
neceffary  to  the  proper  fecretion  of  all  the  various  glands  ;  yet 
perhaps  it  is  not  the  fole  caufe  of  any  of  thefe  numerous  mo- 
tions :  for  as  the  lafteals,  cutaneous  abiorbents,  and  the  various 
glands  appear  to  be  Simulated  into  action  by  the  peculiar  pun- 
gency of  the  fluids  they  abforb,  fo  in  the  inteftinal  canal  the 
pungency  of  the  digefting  aliment,  or  the  acrimony  of  the  fece>s, 
feems  to  contribute,  as  well  as  their  bulk,  to  promote  the  pen- 
flaltic  motions  j  and  in  the  arterial  fyftem,  the  momentum  of  the 
particles  of  the  circulating  blood,  and  their  acrimony,  ftimul  ue 
the  arteries,  as  well  as  the  diftention  occafioned  by  it.  Where 
the  pulfe  is  fmall  this  defect  of  diftention  is  prefent,  nnd  con- 
tributes much  to  produce  the  febris  :irritativa  nulfu  dcbili,  or  ir- 
ritative fever  with  weak  pulfe,  called  by  modern  writers  nervous 
fever,  as  a  predifponent  caufe.  See  Seel.  XII.  i.  4.  Might 
not  the  transfufion  of  blood,  fuppofe  of  four  ounces  daily  +Yo,n 
a  ftrong  man,  or  other  healthful  animal,  as  a  (beep  or  an  afs,  be 
ufed  in  the  early  ftate  of  nervous  or  putrid  fevers  with  great 
profpecl  of  fuccefs  ? 

V.  The  defect  of  the  momentum  of  the  particles  of  the  circu- 
lating blood  is  another  caufe  of  the  quiefcence,  with  which  the 
cold  fits  of  fever  commence.  This  ftimulus  of  the  momentum 
of  the  progreflive  particles  of  the  blood  does  not  act  over  the 
whole  body  like  thofe  of  heat  and  diftention  above  defcribed, 
but  is  confined  to  the  arterial  fyftem  ;  and  differs  from  the 
llimulus  of  the  diftention  of  the  blood,  as  much  as  the  vibra- 
tion of  the  air  does  from  the  currents  of  it.  Thus  are  the  dif- 
ferent organs  of  our  bodies  ftimulated  by  four  different  mechan- 
ic properties  of  the  external  world  :  the  fenfe  of  touch  by  the 
preflure  of  folid  bodies  fo  as  to  diftinguifh  their  figure  ;  the 
mufcular  fyftem  by  the  diftention,  which  they  occafion ;  the  in- 
ternal furface  of  the  arteries,  by  the  momentum  of  their  moving 
particles  ,  and  the  auditory  nerves,  by  the  vibration  oj".  them  : 

and 


29*  DISEASES  SECT.  XXXII.  5.  ^ 

and  thefe  four  mechanic  properties  are  as*  different  from  each 
other  as  the  various  chemical  ones,  which  are  adapted  to  the 
numerous  glands,  and  to  the  other  organs  of  ienfe. 

2.  The  momentum  of  the  progrefiive  particles  of  blood  is 
compounded  of  their  velocity  and  their  quantity  of  matter  :  hence 
whatever  circumftances  diminifh  either  of  thefe  without  propor- 
tionally increafing  the  other,  and  without  fuperadding  either  of 
the  general  ftimuli  of  heat  or  diftention,  will  tend  to  produce  a 
quiefcence  of  the  arterial  fyftem,  and  from  thence  of  ail  the 
other  irritative  motions,  which  are  connected  with  it. 

Hence  in  all  thofe  conftitutions  or  difeafes  where  the  blood 
contains  a  greater  proper  ion  of  ferum,  which  is  the  lighted  part 
of  its  compofition,  the  pulfations  of  the  arteries  are  weaker,  as  in 
nervous  fevers,  chlorofis,  and  hyfteric  complaints ;  for  in  thefe 
cafes  the  momentum  6f  the  progrellive  particles  of  blood  is  lefs  j 
and  hence,  where  the  denfer  parts  of  its  compofition  abound,  as 
the  red  part  of  it,  or  the  coagulable  lymph,  the  arterial  pulfations 
are  ftronger ;  as  in  thofe  of  robuft  health,  and  in  inflammatory 
difeafes. 

That  this  ftimulus  of  the  momentum  of  the  particles  of  the 
circulating  fluid  is  of  the  greateft  confequerrce  to  the  arterial 
adhVn,  appears  from  the  experiment  of  injecting  air  into  the 
blood  veifels,  which  feems  to  deftroy  animal  life  from  the 
want  of  this  ftimuJus  of  momentum  ;  for  the  diftention  of  the 
arteues  is  not  dimimihed  by  it,  it  poflefles  no  corrofive  acrimony, 
and  is  lefs  liable  to  repafs  the  valves  than  the  blood  itfeif ;  fince 
air-valves  in  all  machinery  require  much  lefs  accuracy  of  con- 
ftrudion  than  thofe  which  are  oppofed  to  water. 

3  One  method  of  increailng  the  velocity  of  the  blood,  and  in 
confequence  the  momentum  of  its  particles,  is  by  the  exercife 
of  the  body,  or  by  the  friction  of  its  furface  ;  fo,  on  the  contra- 
ry, too  great  indolence  contributes  to  decreafe  this  ftimulus  of 
the  momentum  of  rhe  particles  of  the  circulating  blood,  and  thus 
tends  to  induce  quiefcence ;  as  is  feen  in  hyfteric  cafes,  and 
chlorofis,  and  the  other  difeafes  of  fedentary  people. 

4.  The  velocity  of  the  particles  of  the  blood  in  certain  cir- 
cum dances  is  increafed  by  venefe£lion,  which,  by  removing  a 
part  of  it,  diminilhes  the  refiftance  to  the  motion  of  the  other 
part,  and  hence  the  momentum  of  the  particles  of  it  is  increaf- 
ed. This  may  be  eafily  underftood  by  confidering  it  in  the  ex- 
treme, fince  if  the  refiftance  was  greatly  increafed,  fo  as  to  over- 
come the  propelling  power,  there  could  be  no  velocity,  and  in 
confequence  no  momentum  at  all.  Fiom  this  circumftance 
arifes  that  curious  phenomenon,  the  truth  of  which  I  have  been 
inore  than  once  witneis  to,  that  venefe&ion  will  often  inftama 

rteouilv 


SECT.  XXXII.  6.  i.        OF  IRRITATION.  293 

neoufly  relieve  thofe  nervous  pains,  which  attend  the  cold  peri- 
eds  of  hyfteric,  afthmatic,  or  epileptic  difeafes ;  and  that  even 
where  large  dofes  of  opium  have  been  in  vain  exhibited.  In 
thefe  cafes  the  pulfe  becomes  ttronger  after  the  bleeding,  and 
the  extremities  re  ain  their  natural  warmth  ;  and  an  opiate  then 
given  a£ts  with  much  more  certain  effe<fi. 

VI.  There  is  another  caufe,  which  feems  occafionally  to  in- 
duce quicfcence  into  fome  part  of  our  fyftem,  I  mean  the  influ- 
ence of  the  fun  and  moon  ;  the  attraction  of  thefe  luminaries, 
by  decreafing  the  gravity  of  the  particles  of  the  blood,  cannot  af- 
fec.1  their  momentum,  as  their  vis  inertiae  remains  the  fame  ; 
but  it  may  neverthelefs  produce  fome  chemical  change  in  them, 
becaufe  whatever  affecls  the  general  ai  tractions  of  the  particles 
of  matter  may  be  fuppofed  from  analogy  to  afreet  their  fpecific 
attractions  or  affinities  :  and  thus  the  Stimulus  of  the  particles 
of  blood  may  be  diminished,  though  not  their  momentum.  As 
the  tides  of  the  fea  obey  the  fouthing  and  northing  of  the  moon 
(alloxving  for  the  time  neceffary  for  their  motion,  and  the  ob- 
ftruclions  of  the  fliores),  it  is  probable,  that  there  are  alfo  at- 
moipheric  tides  on  both  fides  of  the  earth,  which  to  the  inhab- 
itants of  another  planet  might  fo  deflect  the  light  as  to  refemble 
the  ring  of  Saturn.  Now  as  thefe  tides  of  water,  or  of  air,  are 
raifed  by  the  diminution  of  their  gravity,  it  follows,  that  their 
prefTure  on  the  furface  of  the  earth  is  no  greater  than  the  prefTure 
of  rhe  other  parts  of  the  ocean,  or  of  the  atmofphere,  where  no 
fuch  tides  exilt  ;  and  therefore  that  they  cannot  affect  the  mer- 
cury in  the  barometer.  In  the  fame  manner,  the  gravity  of  all 
other  terreltrial  bodies  is  diminished  at  the  times  of  the  fouth- 
ing and  northing  of  the  moon,  and  that  in  a  greater  degree  when 
this  coincides  with  the  fouthing  and  northing  of  the  fun,  and 
this  in  a  Hill  greater  degree  about  the  times  of  the  equinoxes. 
This  decreafe  of  the  gravity  of  all  bodies  during  the  time  the 
moon  pafles  our  zenith  or  nadir  might  poflibly  be  (hewn  by  the 
flower  vibrations  of  a  pendulum,  compared  with  a  fpring  clock, 
or  with  agronomical  obfervation.  Since  a  pendulum  of  a  cer- 
tain length  moves  flower  at  the  line  than  near  the  poles,  becaufe 
the  gravity  being  diminished  and  the  vis  inertiae  continuing  the 
fame,  the  motive  power  is  lefs,  but  the  refiftance  to  be  overcome 
continues  the  fame.  The  combined  powers  of  the  lunar  and 
folar  attraction  are  eftimated  by  Sir  Ifaac  Newton  not  to  exceed 
one  7,868,8501!!  part  of  the  power  of  gravitation,  which  feems 
indeed  but  a  fmall  circumStance  to  produce  any  confiderable  ef- 
fecT:  on  the  weight  of  fublunary  bodies,  and  yet  this  is  fufficient 
to  raife  the  tides  at  the  equator  above  ten  feet  high  ;  and  if  it  be 
considered,  what  fmall  impulfes  of  other  bodies  produce  their 

effefts 


DISEASES  SECT.  XXXII.  6.  i. 

effeflson  the  organs  offenfe  adapted  to  the  perception  of  them, 
as  of  vibration  on  the  auditory  nerves,  we  fhall  ceafe  to  be  fur- 
prifed,  that  fo  minute  a  diminution  in  the  gravity  of  the  parti- 
cles of  blood  (hould  fo  far  afFecl:  their  chemical  changes,  or  their 
ftimulating  quality,  as,  joined  with  other  caufes,  fometimes  to 
produce  the  beginnings  of  difeafes. 

Add  to  this,  that  if  the  lunar  influence  produces  a  very  fmall 
degree  of  quiefcence  at  firft,  and  if  that  recurs  at  certain  peri- 
ods even  with  lefs  power  to  produce  quiefcence  than  at  firft,  yet 
the  quiefcence  will  daily  increafe  by  the  acquired  habit  acting 
at  the  fame  time,  till  at  length  fo  great  a  degree  of  quiefcence  is 
induced  as  to  produce  phrenfy,  canine  madnefs,  epilepfy,  hyfter- 
ic  pains  or  cold  fits  of  fever,  inftances  of  many  of  which  are  to 
be  found  in  Dr,  Mead's  work  on  this  fubjeft.  The  folar  influ- 
ence alfo  appears  daily  in  feveral  difeafes  ;  but  as  darknefs,  fi- 
lence,  fleep,  and  our  periodical  meals  mark  the  parts  of  the  fo- 
lar circle  of  actions,  it  is  fometimes  dubious  to  which  of  thefe 
the  periodical  returns  of  thefe  difeafes  are  to  be  afcribed. 

As  far  as  I  have  been  able  to  obferve,  the  periods  of  inflam- 
matory difeafes  obierve  the  folar  day  ;  as  the  gout  and  rheuma- 
tifm  have  their  greateft  quiefcence  about  noon  and  midnight, 
and  their  exacerbations  fome  hours  after  ;  as  they  have  more 
frequently  their  immediate  caufe  from  cold  air,  inanition,  or  fa- 
tigue, than  from  the  effedls  of  lunations  :  whilft  the  cold  fits  of 
hyileric  patients,  and  thofe  in  nervous  fevers,  more  frequently 
occur  twice  a  day,  later  by  near  half  an  hour  each  time,  accord- 
ing to  the  lunar  day ;  whiift  fome  fits  of  intermittents,  which 
are  undifturbed  by  medicines,  return  at  regular  folar  periods, 
and  others  at  lunar  ones  ;  which  may,  probably,  be  owing  to 
the  difference  of  the  periods  of  thofe  external  circumftances  of 
cold,  inanition,  or  lunation,  which  immediately  caufed  them. 

We  mutt,  however,  obferve,  that  the  periods  of  quiefcence 
and  exacerbation  in  difeafes  do  not  always  commence  at  the  times 
of  the  fyzygies  or  quadratures  of  the  moon  and  fun,  or  at  the 
times  of  their  patting  the  zenith  or  nadir  ;  but  as  it  is  probable, 
that  the  ftimulus  of  the  particles  of  the  circumfluent  blood  is 
gradually  diminimed  from  the  time  of  the  quadratures  to  that  of 
the  fyzygies  the  quiefcence  may  commence  at  any  hour,  when 
co-operating  with  other  caufes  of  quiefcence,  it  becomes  great 
enough  to  produce  a  difeafe  :  afterwards  it  will  continue  to  re- 
cur at  the  lame  period  of  the  lunar  or  folar  influence  ;  the  fame 
caufe  operating  conjointly  with  the  acquired  habit,  that  is  with 
the  catenation  of  this  new  new  motion  with  the  diflevered  links 
of  the  lunar  or  folar  circles  of  animal  a£Hon. 

In  this  manner  the  periods  of  menftruation  obey  the  lunar 

month 


SECT.  XXXII.  7.  i.       OF  IRRITATION.  295 

month  with  great  exaftnefs  in  healthy  patients  (and  perhaps  the 
venereal  orgafrn  in  brute  animals  does  the  fame),  yet  thefc  pe- 
riods do  not  commence  either  at  the  fyzvgies  or  quadratures  of 
the  lunations,  but  at  whatever  time  of  the  lunar  periods  they  be- 
gin, they  obierve  the  fame  in  their  returns  till  fome  greater 
caufe  diiturbs  them. 

.  Hence,  though  the  beft  way  to  calculate  the  time  of  the  ex- 
peded  returns  of  the  paroxyfms  of  periodical  difeafes  is  to  count 
the  number  of  hours  between  the  commencement  of  the  two 
preceding  fits,  yet  the  following  obfervations  may  be  worth  at- 
tending to,  when  we  endeavour  to  prevent  the  returns  of  man- 
iacal or  epileptic  difeafes  ;  whofe  periods  (at  the  beginning  of 
them  efpecially)  frequently  obferve  the  fyzygies  of  the  moon 
and  fun,  and  particularly  about  the  equinox. 

The  greateft  of  the  two  tides  happening  in  every  revolution 
of  the  moon,  is  that  when  the  moon  approaches  neareft  to  the 
zenith  or  nadir  •,  for  this  reafon,  while  the  fun  is  in  the  northern 
figns,  that  is  during  the  vernal  and  fummer  months,  the  greater 
of  the  two  diurnal  tides  in  our  latitude  is  that,  when  the  moon 
is  above  the  horizon  ;  and  when  the  fun  is  in  the  fouthern  figns, 
or  during  the  autumnal  and  winter  months,  the  greater  tide  is 
that,  which  arifes  when  the  moon  is  below  the  horizon  ;  and  as 
the  fun  approaches,  fomewhat  nearer  the  earth  in  winter  than  in 
fummer,  the  greateft  equinoctial  tides  are  obferved  to  be  a  little 
before  the  vernal  equinox,  and  a  little  after  the  autumnal  one. 

Do  not  the  cold  periods  of  lunar  difeafes  commence  a  few 
hours  before  the  fouthing  of  the  moon  during  the  vernal  and 
fummer  months,  and  before  the  northing  of  the  moon  during 
the  autumnal  and  winter  months  ?  Do  not  palfies  and  apoplex- 
ies, which  occu*'  about  the  equinoxes,  happen  a  few  days  before 
the  vernal  equinoctial  lunation,  and  after  the  autumnal  one  ? 
Are  not  the  periods  of  thofe  diurnal  difeafes  more  obftinate, 
that  commence  many  hours  before  the  fouthing  or  northing  of 
the  moon,  than  of  thofe  which  commence  at  thofe  times  ?  Arc 
not  r'"  les  and  apoplexies  more  dangerous  which  com- 

mence many  days  before  the  fyzygies  of  the  moon,  than  thofe 
whicJ:  happen  at  thofe  times  ?  See  Sect.  XXXVI.  on  the  peri- 
ods of  '!-T;ufes. 

VII.  Another  very  frequent  caufe  of  the  cold  fit  of  fever  is 
the  quiefcence  of  fome  of  thofe  large  congeries  of  glands,  which 
compofe  the  liver,  fpiecn,  or  pancreas  ;  one  or  more  of  which 
are  frequently  fo  enlarged  in  the  autumnal  intermittents  as  to 
be  perceptible  to  the  touch  externally,  and  are  called  by  the  vul- 
gar ague-cakas.  As  thefe  glands  are  (limulated  into  acYion  by 
the  fpecific  pungency  of  the  fluids,  which  they  abforb,  the  gener- 
al 


296  DISEASES  SECT.  XXXII.  8.  i, 

al  caufe  of  their  quiefcence  feems  to  be  too  great  infipidity  of 
the  fluids  of  the  body,  co-operating  perhaps  at  the  fame  time 
with  other  general  caufes  of  quiefcence. 

Hence,  in  marfhy  countries  at  cold  f-afons,  which  have  fuc- 
ceedect  hot  ones,  and  amongft  thofe,  who  have  lived  on  innutri- 
tions and  untlimulating  diet,  thefe  agues  are  moil  frequent. 
The  enlargement  of  thefe  quiefcent  vifcera,  and  the  f welling  of 
the  prsecordia  in  many  other  fevers,  is,  mod  probably,  owing  to 
the  fame  caufe  ;  which  may  confift  in  a  general  deficiency  of 
the  production  of  fenforial  power,  as  well  as  in  the  diminished 
ftimulation  of  the  fluids  ;  and  when  the  quiefcence  of  fo  great 
a  number  of  glands,  as  conftitute  one  of  thoie  large  vifcera, 
commences,  all  the  other  irritative  morions  are  affe&ed  by  their 
connexion  with  it,  and  the  cold  fit  of  fever  is  produced 

VIII.  There  are  many  other  caufes,  which  produce  quiefcence 
of  fome  part  of  the  animal  fyftem,  as  fatigue,  hunger,  third,  bad 
diet,  difappointed  love,unwhoiefome  air,  exhauition  from  evacu- 
ations, and  many  others  ;  but  the  laft  caufe,  that  we  fhall  men- 
tion, as    frequently  productive   of  cold  fits  of  fever,  is  fear  or 
anxiety  of  mind.     The  pains,  which  we  are  firft  and  moil  gen- 
erally acquainted  with,  have  been  produced  by  defect  of  fome 
ftimulus  ;  thus,  foon  after   our   nativity  we  become  acquainted 
with  the  pain   from   the  coldnefs  of  the    air,  from  the  want  of 
refpiration,   and  from  the  want  of   food.     Now  all  thefe  pains 
occafioned  by  defect  of  (tirnulus  are  attended  with  quiefcence  of 
the  organ,  and  at  the  fame  time  with  a  greater  or  lefs  degree  of 
quiefcence  of  other  parts  of  the  fyftem  :  thus,  if   we  even  en- 
dure the  pain  of  hunger  fo  as  to  mifs  one  meal  inftead  of  our 
daily  habit  of  repletion,  not   only   the  periftaltic  motions  of  the 
flomach  and  bowels  are  diminifhed,  but  we  are  more  liable  to 
coldnefs  of  our  extremities,  as  of  our  nofes,  and  ears,  and  feet, 
than  at  other  times. 

Now,  as  fear  is  originally  excited  by  our  having  experienced 
pain,  and  is  itfelf  a  painful  affection,  the  fame  quirfcence  of 
other  fibrous  motions  accompanies  it,  as  has  been  molt  frequent- 
ly connected  with  this  kind  of  pain,  as  explained  in  Seel:.  XVI. 
8.  I.  as  the  coldnefs  and  palenefs  of  the  fkin,  trembling,  difficult 
refpiration,  indigeftion,  and  other  fymptoms,  which  contribute 
to  form  the  cold  fit  of  fevers.  Anxiety  is  fear  continued  through 
a  longer  time,  and,  by  producing  chronical  torpor  of  the  fyftem, 
extinguifhes  life  flowly,  by  what  is  commonly  termed  a  brokea 
heart. 

IX.  i.  We  now  ftep    forwards  to  confider  the  other  fymp- 
toms in  con  fequence  of  the   quiefcence  which  begins  the  fits  of 
feyer.     If  by  any  of  the  circumftances  before  deicribed,  or  bf 

two 


SECT.  XXXII.  9.  i.       OF  IRRITATION.  297 

two  or  more  of  them  acting  at  the  fame  time,  a  great  degree  of 
quiefcence  is  induced  on  any  confiderable  part  of  the  circle  of 
irritative  motions,  the  whole  clafs  of  them  is  more  or  lefs  dif- 
turbed  by  their  irritative  aiTociations.  If  this  torpor  be  occa- 
iloned  by  a  deficient  fupply  of  fenforial  power  and  happens  to 
any  of  thofe  parts  of  the  fyftem,  which  are  accu  domed  to  per- 
petual activity,  as  the  vital  motions,  the  torpor  increafes  rapidly, 
becaufe  of  the  great  expenditure  of  feniorial  power  by  the  in- 
ceflant  activity  of  thofe  parts  of  the  fyftem,  as  (hewn  in  No.  3. 
2.  of  this  Section.  Hence  a  deficiency  of  all  the  fecretions  iuc- 
ceeds,  and  as  animal  heat  is  produced  in  proportion  to  the  quan- 
tity of  thofe  fecretions,  the  coldnefs  of  the  (kin  is  the  fird  cir- 
cumftance,  which  is  attended  to.  Dr.  Martin  aflerts,  that  fome 
parts  of  his  body  were  warmer  than  natural  in  the  cold  fit  of 
fever ;  but  it  is  certain,  that  thofe,  which  are  uncovered,  as  the 
fingers,  and  nofe,  and  ears,  are  much  colder  to  the  touch,  and 
paler  in  appearance.  It  is  poilible,  that  his  experiments  were 
made  at  the  beginning  of  the  fubfequent  hot  fits  -,  which  com- 
mence with  partial  diitributions  of  heat,  owing  to  fome  parts  of 
the  body  regaining  their  natural  irritability  fooner  than  others. 

From  the  quiefcence  of  the  anaftomofing  capillaries  a  pale- 
nefs  of  the  (kin  fucceeds,  and  a  lefs  fecretion  of  the  perfpirable 
matter  ;  from  the  quiefcence  of  the  pulmonary  capillaries  a  dif- 
ficulty of  refpiration  arifes  ;  and  from  the  quiefcence  of  the  oth- 
er glands  lefs  bile,  lefs  gaftric  and  pancreatic  juice,  are  fecreted 
into  the  ftomach  and  inteltines,  and  lefs  mucus  and  faliva  are 
poured  into  the  mouth  ;  whence  arifes  the  dry  tongue,  coftive- 
nefs,  dry  ulcers,  and  paucity  of  urine.  From  the  quiefcence  of 
the  abforbent  fyftem  arifes  the  great  third,  as  lefs  moifture  is  ab- 
forbed  from  the  atmofphere.  The  abforption  from  the  atmof- 
phere  was  obferved  by  Dr.  Lifter  to  amount  to  eighteen  ounces 
in  one  night,  above  what  he  had  at  the  fame  time  infenfibly  per- 
fpired.  See  Langrim.  On  the  fame  account  the  urine  is  pale, 
through  in  fmall  quantity,  for  the  thinner  part  is  not  abforbed 
from  it  j  and  when  repeated  ague- fits  continue  long,  the  legs 
fwell  from  the  diminiflied  abforption  of  the  cellular  abforbents. 

From  the  quiefcence  of  the  inteftinal  canal  a  lofs  of  appetite 
and  flatulencies  proceed.  From  the  partial  quiefcence  of  the 
glandular  vifcera  a  fwelling  and  tenfion  about  the  praecordia  be- 
come fenfible  to  the  touch  ;  which  are  occafioned  by  the  delay 
of  the  fluids  from  the  defect  of  venous  or  lymphatic  abforption. 
The  pain  of  the  forehead,  and  of  the  limbs,  and  of  the  fmall  of 
the  back,  arifes  from  the  quiefcence  of  the  membranous  fafcia 
or  mufcles  of  thofe  parts,  in  the  fame  manner  as  the  fkin  be- 
comes painful,  when  the  veflels,  of  which  it  is  compofed,  be* 

VOL.  I.  P  p  come 


298  DISEASES          SECT.  XXXII.  9. 2. 

come  quiefcent  from  cold.  The  trembling  in  confequence  of 
the  pain  of  coldnefs,  the  reflleflhefs,  and  the  yawning,  and 
ftretching  of  the  limbs,  together  with  the  fhuddering,  or  rigors, 
are  convulfive  motions ;  and  will  be  explained  amongft  the  dif- 
eaies  of  volition  ;  Sett.  XXXIV. 

Sicknefs  and  vomiting  are  a  frequent  fymptom  in  the  begin- 
nings of  fever-fits,  the  mufcular  fibres  of  the  ftomach  fhare  the 
general  torpor  and  debility  of  the  fyftem  ;  their  motions  become 
firft  lefTened,  and  (lop,  and  then  become  retrograde  ;  for  the  acl  of 
vomiripg,  like  the  globus  hyftericus  arid  the  borborigmi  of hypo- 
chondriafis,  is  always  a  fymptom  of  debility,  either  from  want  of 
ftimulus,  as  in  hunger  j  or  from  want  of  fenforial  power,  as  af- 
ter intoxication  ;  or  from  fympathy  with  fome  other  torpid  ir- 
ritative motions,  as  in  the  cold  fits  of  ague.  See  Seel.  XII.  5. 
5.  XXIX.  1 1.  and  XXXV.  i.  3.  where  this  acl;  of  vomiting  is 
further  explained. 

The  imall  pulfe,  which  is  faid  by  fome  writers  to  be  flow  at 
the  commencement  of  ague-fits,  and  which  is  frequently  trem- 
bling and  intermittent,  is  owing  to  the  quiefcence  of  the  heart 
and  arterial  fyftem,  and  to  the  refiftance  oppofed  to  the  circu- 
lating fluid  from  the  inactivity  of  all  the  glands  and  capillaries. 
The  great  weaknefs  and  inability  to  voluntary  motions,  with  the 
inftnfibility  of  the  extremities,  are  owing  to  the  general  quief- 
cence of  the  whole  moving  fyftem  ;  or,  perhaps,  fimply  to  the 
deficient  production  of  fenforial  power. 

If  all  thefe  fymptoms  are  further  increafed,  the  quiefcence  of 
all  the  mufcles,  including  the  heart  and  arteries,  becomes  com- 
plete, and  death  enfues.  This  is,  moft  probably,  the  cafe  of 
thofe  who  are  ftarved  to  death  with  cold»  and  of  thofe  who  are 
faid  to  die  in  Holland  from  long  fkating  on  their  frozen  canals. 

2.  As  foon  as  this  general  quiefcence  of  the  fyftem  ceafes, 
either  by  the  diminution  of  the  caufe,  or  by  the  accumulation  of 
fenforial  power,  (as  in  fyncope,  Seel-  XII.  7.  i.  )  which  is  the 
natural  confequence  of  previous  quiefcence,  the  hot  fit  com- 
mences. Every  gland  of  the  body  is  now  ftimulated  into 
ftronger  aclion  than  is  natural,  as  its  irritability  is  increafed  by 
accumulation  of  fenforial  power  during  its  late  quiefcence,  a  fu- 
perabundance  of  all  the  fecretions  is  produced  and  an  increafe 
of  heat  in  confequenee  of  the  increafe  of  thefe  fecretions.  The 
{kin  becomes  red,  and  the  perfpirarion  great,  owing  to  the  in- 
creafed aclion  of  the  capillaries  during  the  hot  part  of  the  par- 
oxyfm.  The  fecretion  of  perfpirable  matter  is  perhaps  greater 
during  the  hot  fit  than  in  the  fweating  fit  which  follows  j  but 
as  the  abforption  of  it  alfo  is  greater,  it  does  not  ftand  on  the 
{kin  in  vifible  drops  :  add  to  this,  that  the  evaporation  of  it  alfo 

is 


SECT.  XXXII.  9.  2.       OF  IRRITATION.  299 

is  greater,  from  the  increafed  heat  of  the  fldn.  But  at  the  de- 
cline of  the  hot  fit,  as  the  mouths  of  the  abforbents  of  the  fkin 
are  expofed  to  the  cooler  air,  or  bed-clothes,  thefe  veffels  fooner 
lofe  their  increafed  activity,  and  ceafe  to  abforb  more  than  their 
natural  quantity  :  but  the  fecerning  vefTels  for  fome  time  longer, 
being  kept  warm  by  the  circulating  blood,  continue  to  pour  out 
an  increafed  quantity  of  perfpirable  matter,  which  no\v  Hands 
on  the  (kin  in  large  vifible  drops  *,  the  exhalation  of  it  alfo  being 
leflcned  by  the  greater  coolnefs  of  the  fkin,  as  well  as  its  abibrp- 
tion  by  the  diminifhed  action  of  the  lymphatics.  See  Clafs  I. 
I.  2.  3. 

The  increafed  fecretion  of  bile  and  of  other  fluids  poured  in- 
to the  inteftines  frequently  induces  a  purging  at  the  decline  of 
the  hot  fit ;  for  as  the  external  abforbent  veflels  have  their 
mouths  expofed  to  the  cold  air,  as  above  mentioned,  they  ceafe 
to  be  excited  into  unnatural  activity  fooner  than  the  fecretory 
veflels,  whofe  mouths  are  expofed  to  the  warmth  of  the  blood  : 
now,  as  the  internal  abforbents  fympathize  with  the  external 
ones,  thefe  alfo,, which  during  the  hot  fit  drank  up  the  thinner 
part  of  the  bile,  or  of  other  fecreted  fluids,  lofe  their  increafed 
activity  before  the  gland  lofes  its  increafed  activity,  at  the  de- 
cline of  the  hot  fit ;  and  the  loofe  dejections  are  produced  from 
the  fame  caufe  that  the  increafed  perlpiration  {lands  on  the  fur- 
face  of  the  fkin,  from  the  increafed  abibrption  ceafmg  fooner 
than  the  increafed  fecretion. 

The  urine  during  the  cold  fit  is  in  fmall  quantity  and  pale, 
both  from  a  deficiency  of  the  fecretion  and  a  deficiency  of  the 
abforption.  During  the  hot  fit  it  is  in  its  ufual  quantity,  but 
very  high  coloured  and  turbid,  becaufe  a  greater  quantity  had 
been  fecreted  by  the  increafed  action  of  the  kidneys,  and  alfo  a 
greater  quantity  of  its  more  aqueous  part  had  been  abforbed  from 
it  in  the  bladder  by  the  increafed  adtion  of  the  abforbents  ;  and 
laltly,  at  the  decline  of  the  hot  fit  it  is  in  large  quantity  and  lefs 
coloured,  or  turbid,  becaufe  the  abforbent  veflels  of  the  bladder, 
as  obferved  above,  lofe  their  increafed  action  by  fympathy  with 
the  cutaneous  ones  fooner  than  the  fecretory  veflels  of  the  kid- 
neys iofe  their  increafed  activity.  Hence  the  quantity  of  the  fed- 
iinent,  and  the  colour  of  the  urine,  in  fevers,  depend  much  on  the 
quantity  fecreted  by  the  kidneys,  and  the  quantity  abforbed  from 
it  again  in  the  bladder  :  the  kinds  of  fediment,  as  the  lateritious, 
purulent,  mucous,  or  bloody  fediments,  depend  on  other  caufes. 
It  ihould  be  obferved,  that  if  the  fweating  be  increafed  by  the 
heat  of  the  room,  or  of  the  bed-clothes,  a  paucity  of  turbid  urine 
will  continue  to  be  produced,  as  the  abforbents  of  the  bladder 
will  have  their  activity  increafed  by  their  fympathy  with  the 

veflels 


300  DISEASES  SECT.  XXXII,  9.  3. 

veflels  of  the  fkin,  for  the  purpofe  of  fupplying  the  fluid  expend- 
ed in  perfpiration. 

The  pulfe  becomes  ftrong  and  full,  owing  to  the  increafed  ir- 
ritability of  the  heart  and  arteries,  from  the  accumulation  of  fen- 
forial  power  during  their  quiefcence,  and  to  the  quicknefs  of 
the  return  of  the  blood  from  the  various  glands  and  capillaries. 
This  increafed  action  of  all  the  fecretory  veflels  does  not  occur 
very  fuddenly,  nor  univerfally  at  the  fame  time.  The  heat  feems 
to  begin  about  the  centre,  and  to  be  dirTufed  from  thence  irregu- 
larly to  the  other  parts  of  the  fyftem.  This  may  be  owing  to 
the  fituacion  of  the  parts  which  firft  became  quiefcent  and  caufed 
the  fever-fit,  efpecially  when  a  hardnefs  or  tumour  about  the 
prxcordia  can  be  felt  by  the  hand  ;  and  hence  this  part,  in 
whatever  vifcus  it  is  feated,  might  be  the  firft  to  regain  its  nat- 
ural or  increafed  irritability. 

3.  It  mud  be  here  rioted,  that,  by  the  increafed  quantity  of 
heat,  and  of  the  impulfe  of  the  blood  at  the  commencement  of 
the  hot  fiu  a  great  increafe  of  ftimulus  is  induced,   and  is  now 
added  to  the  increafed  irritability  of  the  fyftem,  which  was  oc- 
cafioned  by   its  previous  quiefcence.     This  additional  ftimulus 
cf  heat  and  momentum  of  the  blood  augments  the  violence  of 
the   movements  of  the   arterial  and  glandular  fyftem  in  an  in- 
creafing  ratio.     Theie   violent   exertions   ftill   producing  more 
heat  and  greater  momentum  of  the  moving  fluids,  till  at  length 
the  ienforial   power  becomes   wafted  by  this  great  ftimulus  be- 
neath its  natural  quantity,  and  predifpofes  the  fyftem  to  a  fec- 
ond  cold  fit. 

At  length  all  thefe  unnatural  exertions  fpontaneoufly  fubfide 
with  the  increafed  irritability  that  produced  them  ;  and  which 
was  itfelf  produced  by  the  preceding  quiefcence,  in  the  fame 
manner  as  the  eye,  on  coming  from  darknefs  into  day-light,  in 
a  little  time  ceafes  to  be  dazzled  and  pained,  and  gradually  re- 
covers its  natural  degree  of  irritability. 

4.  But  if  the  increafe  of  irritability,  and  the  confequent  in* 
creafe  of  the  ftimulus  of  heat  and  momentum,  produce   more 
violent  exertions  than  thofe  above  defcribed  ;  great  pain  arifes 
in  fome  part  of  the  moving  fyftem,  as  in  the  membranes  of  the 
brain,  pleura,  or  joints  ;   and  new  motions  of  the  veflels  are  pro- 
duced in  confequence  of  this  pain,  which  are  called  inflamma- 
tion ;  or  delirium  or  ftupor  arifes  •,  as  explained  in  Seel.  XXI. 
and  XXXIII.  :   for  the  immediate  effed  is  the  fame,  whether 
the  great  energy  of  the  moving  organs  arifes  from  an  increaie  oi 
ftimulus  or  an  increafe  of  irritability  j  though  in  the  former  cafe 
the  wafte  of  fenforiai  power  leads  to  debility,  and  in  the  latter 
to  health. 

Recapitulation  * 


SECT.  XXXII.  i®.  i.      OF  IRRITATION  301 


Recapitulation. 

X.  Thofe  mufcles  which  are  lefs  frequently  exerted,  and 
whofe  actions  are  interrupted  by  deep,  acquire  lefs  accumulation 
of  enforial  power,  during  their  quiefcent  ftate,  as  the  mufcles 
of  locomotion.  In  thefe  mufcles  after  great  exertion,  that  is, 
after  great  exhauftion  of  the  fenforial  power,  the  pain  of  fatigue 
enfues  *,  and  during  reft  there  is  a  renovation  of  the  natural 
quantity  of  fenforial  power  ;  but  where  the  reft,  or  quiefcence 
of  the  mufcle,  is  long  continued,  a  quantity  of  fenforial  power 
becomes  accumulated  beyond  what  is  neceflary ;  as  appears  by 
the  uneafinefs  occafioned  by  want  of  exercife  ;  and  which  in 
young  animals  is  one  caufe  exciting  them  into  a£tion,  as  is  feen 
in  the  play  of  puppies  and  kittens. 

But  when  thofe  mufcles,  which  are  habituated  to  perpetual 
actions,  as  thofe  of  the  ftomach,  by  the  ftimulus  of  food,  thofe 
of  the  veffeis  of  the  fkin  by  the  ftimulus  of  heat,  and  thofe  which 
conftitute  the  arteries  and  glands  by  the  ftimulus  of  the  blood, 
become  for  a  time  quiefcent,  from  the  want  of  their  appropria- 
ted ftimuli,  or  by  their  aflbciation  with  other  quiefcent  parts  of 
the  fyitem  ;  a  greater  accumulation  of  fenforial  power  is  ac- 
quired during  their  quiefcence,  and  a  greater  or  quicker  ex- 
hauition  of  it  is  produced  during  their  increafed  action. 

This  accumulation  of  fenforial  power  from  deficient  action, 
if  it  happens  to  the  ftomach  from  want  of  food,  occafions  the 
pain  of  hunger ;  if  it  happens  to  the  vefTels  of  the  fkin  from 
want  of  heat,  it  occafions  the  pain  of  cold  ;  and  if  to  the  arterial 
fyftem  from  the  want  of  its  adapted  ftimuli,  many  difagreeable 
fenfations  are  occafioned,  fuch  as  are  experienced  in  the  cold  fits 
of  intermittent  fevers,  and  are  as  various  as  there  are  glands  or 
membranes  in  the  fyftem,  and  are  generally  termed  univerfal 
uneafinefs. 

When  the  quiefcence  of  the  arterial  fyftem  is  not  owing  to  de- 
fect of  ftimulus  as  above,  but  to  the  defective  quantity  of  fenfo- 
rial power,  as  in  the  commencement  of  nervous  fever,  or  irrita- 
tive fever  with  weak  pulfe,  a  great  torpor  of  this  fyftem  is 
quickly  induced  ;  becaufe  both  the  irritation  from  the  ftimulus 
or  the  blood,  and  the  aflbciations  of  the  vafcular  motions  with 
each  other,  continue  to  excite  the  arteries  into  action,  and  thence 
quickly  exhauft  the  iil-fupplied  vafcular  mufcles  ;  for  to  reft 
is  death ,  and  therefore  thofe  vafcular  mufcles  continue  to  pro- 
ceed, though  with  feebler  action,  to  the  extreme  of  wearinefs 
or  faintnefs  :  while  nothing  fimilar  to  this  affects  the  locomo- 
tive mufcles,  whofc  aft  ions  are  generally  caufed  by  volition,  and 

not 


3o2  DISEASES          SECT.  XXXII.  i®.  j. 

not  much  fubjecl  either  to  irritation  or  to  other  kinds  of  afib- 
ciations  befides  the  voluntary  ones,  except  indeed  when  they 
are  excited  by  the  lafh  of  ilavery. 

In  thefe  vafcular  mufcles,  which  are  fubjecl  to  perpetual  ac- 
tion, and  thence  liable  to  great  accumulation  of  fenforial  power 
during  their  quiefcence  from  want  of  ftimulus,  a  great  increafe 
of  activity  occurs,  either  from  the  renewal  of  their  accuftomed 
ftimulus,  or  even  from  much  lefs  quantities  of  ftimulus  than  ufu- 
al.  This  increafe  of  aclion  conflitutes  the  hoc  fit  of  fever, 
which  is  attended  with  various  increased  fecretions,  with  great 
concomitant  heat,  and  general  uneafmefs.  The  uneafinefs  at- 
tending this  hot  paroxyfm  of  fever,  or  fit  of  exertion,  is  very  dif- 
ferent from  that,  which  attends  the  previous  cold  fit,  or  fit  of 
quiefcence,  and  is  frequently  the  caufe  of  inflammation,  as  in 
pleurify,  which  is  treated  of  in  the  next  feel  ion. 

A  fimilar  effecl  occurs  after  the  quiefcence  of  our  organs  of 
fenfe  j  thofe  which  are  not  fubjecl  to  perpetual  aclion,  as  the 
taiie  and  fmell,  are  lefs  liable  to  an  exuberant  accumulation  of 
fenforial  power  after  their  having  for  a  time  been  maftive  ;  but 
the  eye,  which  is  in  perpetual  aclion  during  the  day,  becomes 
dazzled,  and  liable  to  inflammation  after  a  temporary  quiefcence. 

Where  the  previous  quiefcence  has  been  owing  to  a  defecl  of 
fenforial  power,  and  not  to  a  defecl  of  iiimulus,  as  in  the  irrita- 
tive fever  with  weak  pulfe,  a  fimilar  increafe  of  activity  of  the 
arterial  fyftem  fucceeds,  either  from  the  uiual  ftimulus  of  the 
blood,  or  from  a  ftimulus  lefs  than  ufual  \  but  as  there  is  in 
general  in  thefe  cafes  of  fever  with  weak  pulfe  a  deficiency  of 
the  quantity  of  the  blood,  the  pulfe  in  the  hot  fit  is  weaker  than 
in  health,  though  it  is  ftronger  than  in  the  cold  fit,  as  explained 
in  No  2.  of  this  fettion.  But  at  the  fame  time  in  thofe  fevers, 
where  rhe  defect  of  irritation  is  owing  to  the  defect  of  the 
quantity  of  fenforial  power,  as  well  as  to  the  defecl  of  ftimulus, 
another  circumftance  occurs  \  which  confifts  in  the  partial  dif- 
tribution  of  it,  as  appears  in  partial  fluihings,  as  of  the  face  or 
bolom,  while  the  extremities  are  cold  ;  and  in  the  increafe  of 
particular  fecretions,  as  of  bile,  faliva,  infenfible  perfpiration, 
with  great  heat  of  the  fkin,  or  with  partial  fweats,  or  diarrhoea. 

There  are  alfo  many  uneafy  fenfations  attending  thefe  in- 
creafed  aclionsv  which  like  thofe  belonging  to  the  hot  fit  of  fe- 
ver with  ftrong  pulfe,  are  frequently  followed  by  inflammation, 
as  in  fcariet  fever  ;  which  inflammation  is  neverthelefs  accom- 
pained  with  a  pulfe  weaker,  though  quicker,  than  the  pulfe  du- 
ring the  remiffion  or  intermiflion  of  rhe  paroxyfms,  though 
ftronger  than  that  of  the  previous  cold  fit. 

From  hence  I  conclude,  that  both  the  cold  and  hot  fits  of  fe- 
ver 


SECT.  XXXIL  1 1.  i.      OF  IRRITATION.  303 

ver  are  neceflary  confequenccs  of  the  perpetual  and  inceffant 
action  of  the  arterial  and  glandular  fyftem  ;  fince  thofe  mufcu- 
lar  fibres  and  thofe  organs  of  fenfe,  which  are  moll  frequently 
exerted,  become  neceflarily  mod  affected  both  with  defect  and 
accumulation  of  fenforial  power  :  and  that  \\zncefever-jits  are 
not  an  effort  of  nature  to  relieve  herfelf>  and  that  therefore  they 
{hould  always  be  prevented  or  diminifhed  as  much  as  poflible, 
by  any  means  which  decreafe  the  general  or  partial  vafcular  ac- 
tions, when  they  are  greater,  or  by  increafing  them  when  they 
are  kfs  than  in  health,  as  defcribed  in  Sect.  XII.  6.  i. 

Thus  have  I  endeavoured  to  explain,  and  I  hope  to  the  fatis- 
faclion  of  the  candid  and  patienc  reader,  the  principal  fymp- 
toms  or  circumftances  of  fever  without  the  introduction  of  the 
fupernatural  power  of  fpafm.  To  the  arguments  in  favour  of 
the  doftrine  of  fpafm  it  may  be  fufficient  to  reply,  that  in  the 
evolution  of  medical  as  well  as  of  dramatic  cataftrophe, 

Nee  Deus  interfit,  nifi  dignus  vindice  nodus 
Incident.  HOR, 

XI.  i.  Since  I  printed  the  above  in  the  firft  edition  of  this 
work,  I  am  told,  that  the  fpafmodic  doctrine  of  fever  has  yet  its 
advocates  ;  who  believe  that  the  coldnefs  at  the  beginning  of  in- 
termittent fevers  is  owing  to  a  fpafm  of  the  cutaneous  veflels. 
But  as  the  fkin  is  at  that  time  lax  and  foft,  the  mufcular  fibres 
of  thofe  cutaneous  veflels  cannot  be  in  action  or  contraction, 
which  conltitute  fpafm.  Whence  we  have  the  evidence  both 
of  our  fight  and  touch  againtt  this  wild  imagination. 

Others  have  advanced,  that  this  fpafmodic  contraction  of  the 
cutaneous  veflels  or  pores  confines  the  heat,  or  drives  it  to  the 
heart  ;  which  in  the  hot  fit  of  fever  repels  the  heat  again  to  the 
fkin  by  its  reaction.  Thofe,  who  efpoufe  this  doctrine,  feem  to 
conceive,  that  the  particles  of  heat  are  as  large  asfhot-corns,  or 
as  the  globules  of  blood  ;  and  not  that  it  is  an  ethereal  fluid*  in. 
which  all  things  are  immerfed,  and  by  which  all  things  are 
penetrated  ;  an  opinion  which  originated  from  Galen,  and  mufb 
have  been  founded  on  a  total  ignorance  of  chemiftry,  and  natu- 
ral philoi'ophy.  Others,  I  hear,  ftili  fuppofe  cold  to  be  a  ftimu- 
lus,  not  understanding  that  it  is  fimply  the  abfence  of  heat-,  and 
that  darkneis  might  as  well  be  called  a  (timulus  to  the  eye,  or 
hunger  a  itimulas  to  the  ftomach,  as  cold  to  our  fenfe,  which 
perceives  heat ;  which  is  commonly  confounded  with  our  fenfe 
of  touchj  which  perceive  figure.  The  pain,  which  we  experi- 
ence on  being  expofed  to  a  want  of  heat,  which  is  termed  chill- 
nefs,  or  coldnefs  j  and  the  pain  we  experience  in  our  organs  of 

digeition 


3o4  DISEASES         ^SECT. XXXII.  n.  i, 

digeftion  from  the  want  of  food,  which  is  termed  hunger ;  both 
arife  from  the  inactivity  of  thole  vefiels,  which  ought  to  be  either 
perpetually,  or  at  periodical  times  ftimulated  into  action.  See 
Sect.  XIII.  3.  2.  And  the  ftiivering  or  actions  of  the  fubcuta- 
neous  mufcles,  when  we  are  cold,  are  in  confequence  of  the 
pain,  or  voluntary  exertion  to  relieve  that  pain,  and  originate 
from  the  want  of  ftimulus,  not  from  the  excefs  of  it. 

In  this  age  of  reafon  it  is  not  the  opinions  of  others,  but  the 
natural  phenomena,  on  which  thofe  opinions  are  founded, 
which  deferve  to  be  canvafled.  And  with  the  fuppofed  exift- 
ence  of  ghofts  or  apparitions,  witchcraft,  vampyrifm,  aftrology, 
animal  magnetifm,  and  American  tractors,  fuch  theories  as  the 
above  muft  vanifh  like  the  fcenery  of  a  dream  j  as  they  confift 
of  fuch  combinations  of  ideas,  as  have  no  prototype  or  corref- 
pondent  combinations  of  material  objects  exifting  in  nature. 


SECT, 


SECT.  XXXIII.  i.  i.       OF  SENSATION.  305 

SECT.       XXXIIL 

DISEASES    OF    SENSATION. 

I.  i.  Motions  excited  by  fenfation.  Digeftion.  Generation.  Pleaf* 
lire  of  exigence.  Hypochondriacifm.  2.  Pain  introduced.  Sen~ 
Jitive  fevers  of  two  kinds.  3.  Two  fenforial  powers  exerted  in 
fenjitive  fevers.  Size  of  the  blood.  Nervous  fevers  dijiingttifhed 
from  putrid  ones.  The  fcptic  and  antifeptic  theory.  4.  Two 
kinds  of  delirium.  5.  Other  animals  are  lefs  liable  to  delirium , 
cannot  receive  our  contagious  difeafesy  and  are  lefs  liable  to  madnefs. 
II.  i.  Senjitive  motions  generated.  2-  Inflammation  explained. 
3.  Its  remote  caufes  from  excefs  of  irritation  ^  or  of  irritability,  not 
from  thofe  pains  which  are  owing  to  defecJ  of  irritation.  New  vef- 
fels  produced,  and  much  heat .  4.  Purulent  matter  fecre ted.  5.  Con- 
tagion explained.  6.  Received  but  once.  7.  If  common  matter 
be  contagious  ?  8.  Why  fome  contagions  are  received  but  once.  9. 
Why  others  may  be  received  frequently.  Contagions  of  fm  all-pox 
and  meajles  do  not  act  at  the  fame  time.  Two  cafes  of  fuch  pa- 
tients. 10.  The  blood  from  patients  in  the  f mall  pox  will  not  in- 
feel  others.  Cafes  of  children  thus  inoculated.  The  variolous  con- 
tagion is  not  received  into  the  blood.  It  acls  by  fenfitive  ajjociation 
between  the  Jlomach  and  Jkir. .  III.  I.  Abforption  of  fo lids  and 
fluids,  2.  Art  of  healing  ulcers.  3.  M.ortif  cation  attended 
ivith  lefs  pain  in  weak  people. 

I.  i.  As  many  motions  of  the  body  are  excited  and  continu- 
ed by  irritations,  fo  others  require  either  conjunftly  with  thefe, 
or  feparately,  the  pleafurable  or  painful  fenfations,  for  the  pur- 
pofeof  producing  them  with  due  energy.  Amongft  thefe  the 
bufinefs  of  digeftion  fupplies  us  with  an  inftance  :  if  the  food, 
•which  we  fwallow,  is  not  attended  with  agreeable  fenfations,  it 
digefts  lefs  perfe&ly;  and  if  very  difagreeable  fenfation  accom- 
panies it,  fuch  as  a  naufeous  idea,  or  very  difguflful  tafte,  the 
digeftion  becomes  impeded  j  or  retrograde  motions  of  the  (lom- 
ach  and  oefophagus,  fucceed,  and  the  food  is  ejected. 

The  bufinefs  of  generation  depends  fo  much  on  agreeable  fen- 
fation, that,  where  the  object  is  difguftful,  neither  voluntary  ex- 
ertion nor  irritation  can  effeft  the  purpofe  :  which  is  alfo  liable 
to  be  interrupted  by  the  pain  of  fear  or  bafhfulnefs. 

Befides  the  pleafure,  which  attends  the  irritations  produced  by 
the  objefts  of  lull  and  hunger,  there  feems  to  be  a  fum  of  pleaf- 
urable affe&ion  accompanying  the  various  fecretions  of  the  nu- 
merous glands,  which  conftitute  the  pleafure  of  life,  in  comradif- 

VOL,  I. 


306  DISEASES  SECT.  XXXIII.  1.2, 

tin&ion  to  the  tedium  vit?c.  This  quantity  or  fum  of  pleafura- 
ble  affection  feems  to  contribute  to  the  due  or  energetic  per- 
formance of  the  whole  moveable  fyftem,  as  well  that  of  the  heart 
and  arteries,  as  of  digeflion  and  of  abforp^ion  *,  fince  without 
the  due  quantity  of  pleafurable  fenfation,  flatulency  and  hypo- 
chondriacifm  affects  the  inteftines,  and  a  languor  feizes  the  arte- 
rial pulfations  and  fecretions  ;  as  occurs  in  great  and  continued 
anxiety  of  the  mind. 

2.  Befides  the  febrile  motions  occauoned   by  irritation,  de- 
fcribed  in  Seel.  XXXII.  and  termed  irritative  fever,  it  frequent- 
ly happens  that  pain  is  excited  by  the  violence  of  the  fibrous 
contractions  ;  and  other  new  motions  are  then  fuperadded,   in 
confequence  of  fenfation,  which  we  {hall  term  febris  fenfitiva, 
or  fenfitive  fever.     It  mud  be  obferved,  that  moft  irritative  fe- 
vers begin  with  a  decreafed  exertion  of  irritation  owing  to  de- 
fed!  of  (limulus  ;  but  that  on  the  contrary  the  fenfitive  fevers 
or  inflammations,  generally  begin  with  the  increafed  exertion  of 
fenfation,  as  mentioned  in  Seel.  XXXI  on  temperaments :  for 
though  the  cold  fit,  which  introduces  inflammation,  commences 
with  decreafed  irritation,  yet  the  inflammation  itfelf  commences 
in  the  hot  fit  during  the  increafe  of  fenfation.     Thus  a  common 
puflule,  or  phlegmon,  in  a  part  of  little  fenfibiiity  does  not  ex- 
cite an  inflammatory  fever  ;    but  if  the  ftomach,  inteftines,  or 
the  tender  fubftance  beneath  the  nails,  be  injured,  great  fenfa- 
tion is  produced,  and  the  whole  fyltem  is  thrown  into  that  kind 
of  exertion,  which  conftitutes  inflammation. 

Thefe  fenfitive  fevers,  like  the  irritative  ones,  refolve.them- 
felves  into  thofe  with  arterial  ftrength,  and  thofe  with  arterial 
debility,  that  is  with  excefs  or  defect  of  fenforial  power  ;  thefe 
may  be  termed  the  febris  fenfitiva  pulfu  forti,  fenfitive  fever 
with  ftrong  pulfe,  which  is  the  fynocha,  or  inflammatory  fever  ; 
and  the  febris  fenfitiva  pulfu  debili,  fenfitive  fever  with  weak 
puife,  which  is  the  typhus  gravior,  or  putrid  fever  of  fome 
writers 

3.  The  inflammatory  fevers,  which  are  here  termed  fenfitive 
fevers  with  ftrong  pulfe,  are  generally  attended  with  fome  topical 
inflammation,  as  pleurify,  peripneumony,  or  rheumatifm,  which 
diftinguifhes  them  from  irritative  fevers  with  ftrong  pulfe.     The 
pulfe  is  ftrong,  quick,  and  full ,  for  in  this  fever  there  is  great 
irritation,  as  well  as  great  fenfation,   employed  in  moving  the 
arterial  fyftem.     The  fize,  or  coagulabte  lymph,  which  appears 
on  the  blood,   is  probably  an   increafed  fecretion  from  the  in- 
flamed internal  lining  of  the  whole  arterial  fyftem,  the  thinner 
part  being  taken  away  by  the  increafed  abforption  of  the  in- 
flamed lymphatics. 

The 


SECT.  XXXIIL  i.  4.         OF  SENSATION.  307 

The  fenfitive  fevers  with  weak  pulfe,  which  are  termed  putrid 
or  malignant  fevers,  are  diitinguifhed  from  irritative  fevers  with 
weak  pulfe,  called  nervous  fevers,  defcribed  in  the  laft  fetlion, 
as  the  former  confift  of  inflammation  joined  with  debility,  and 
the  latter  of  debility  alone.  Hence  there  is  greater  heat  and 
more  florid  colour  of  the  fkin  in  the  former,  with  petechise,  or 
purple  fpots,  and  aphthae,  or  floughsin  the  throat,  and  generally 
with  previous  contagion. 

When  animal  matter  dies,  as  a  (lough  in  the  throat,  or  the 
mortified  part  of  a  carbuncle,  if  it  be  kept  moid  and  warm,  as 
during  its  adhefion  to  a  living  body,  it  will  foon  putrify.  This 
and  the  origin  of  contagion  from  putrid  animal  fubftances,  feem 
tohave  given  rife  to  the  feptic  and  antifeptic  theory  of  thcfe  fevers. 

The  matter  in  puftules  and  ulcers  is  thus  liable  to  become 
putrid,  and  to  produce  microfcopic  animalcula  ;  the  urine,  if  too 
k)rtg  retained,  may  alfo  gain  a  putrefcent  fmell,  as  well  as  the 
alvine  feces  ;  but  fome  writers  have  gone  fo  far  as  to  believe, 
that  the  blood  itfelf  in  thefe  fevers  has  fmelt  putrid,  when  drawn 
from  the  arm  of  the  patient  ;  but  this  feems  not  well  founded  ; 
fmce  a  fingle  particle  of  putrid  matter  taken  into  the  blood  can 
produce  fever,  how  can  we  conceive  that  the  whole  mafs  could 
continue  a  minute  in  a  putrid  ftate  without  deftroying  life  ? 
Add  to  this,  that  putrid  animal  fubftances  give  up  air,  as  in 
gangrenes  ;  and  that  hence  if  the  blood  was  putrid,  air  fhould 
be  given  out,  which  in  the  blood- veiTels  is  known  to  occafion 
immediate  death. 

In  thefe  fenfitive  fevers  with  ftrong  pulfe  (or  inflammations) 
there  are  two  fenforial  faculties  concerned  in  producing  the  dif- 
eafe,  viz.  irritation  and  fenfation  ;  and  hence,  as  their  combined 
a&ion  is  more  violent,  the  general  quantity  of  fenforial  power 
becomes  further  exhaufted  during  the  exacerbation,  and  the 
fyftem  more  rapidly  weakened  than  in  irritative  fever  with 
icrong  pulfe  ;  where  the  fpirit  of  animation  is  weakened  by  but 
one  mode  of  its  exertion  :  fo  that  this  febris  fenfitiva  pulfu  forti 
(or  inflammatory  fever)  may  be  confidered  as  the  febris  irritativa 
pulfu  forti,  with  the  addition  of  inflammation  ;  and  the  febris 
fenfitiva  pulfu  debili  (or  malignant  fever)  may  be  confidered  as 
*he  febris  irritativa  pulfu  debili  (or  nervous  fever)  with  the  addi- 
tion of  inflammation. 

4.  In  thefe  putrid  or  malignant  fevers  a  deficiency  of  irrita- 
bility accompanies  the  increafe  of  fenfibility  ;  and  by  this  waft*; 
of  fenforial  power  by  the  excefs  of  fenfation,  which  was  already 
too  fmall,  arifes  the  'delirium  and  ftupor  which  fo  perpetually  at* 
tend  thefe  inflammatory  fevers  with  arterial  debility.  In  thefe 
cafes  the  voluntary  power  firft  ceafes  to  a£l  from  deficiency  of 

fenforiai 


3o8  DISEASES          SECT.  XXXIII.  i.  4. 

fenforial  fpirit  •,  and  the  ftimuli  from  external  bodies  have  no 
effect  on  the  exhaufted  fenforial  power,  and  a  delirium  like  a 
dream  is  the  confequence.  At  length  the  internal  ilimuli  ceale  to 
excite  fufficient  irritation,  and  the  fecretions  are  either  not  pro- 
duced at  all,  or  too  parfimonious  in  quantity.  Amongft  thefe 
the  fecretion  of  the  brain,  or  production  of  the  fenforial  power, 
becomes  deficient,  till  at  laft  all  fenforial  power  ceafes,  except 
what  is  juft  neceflary  to  perform  the  vital  motions,  and  a  ftupor 
fucceeds  ;  which  is  thus  owing  to  the  fame  caufe  as  the  prece- 
ding delirium  exerted  in  a  greater  degree. 

This  kind  of  delirium  is  owing  to  a  fufpenfion  of  volition,  and 
to  the  difobedience  of  the  fenfes  to  external  ftimuli,  and  is  always 
occafioned  by  great  debility,  or  paucity  of  fenforial  power  ;  it 
is  therefore  a  bad  fign  at  the  end  of  inflammatory  fevers,  which 
had  previous  arterial  flrength,  as  rheumatifm,  or  pleurify,  as  it 
(hews  the  prefence  of  great  exhauftion  of  fenforial  power  in  a 
fyftem,  which  having  lately  been  expofed  to  great  excitement,  is 
not  fo  liable  to  be  ftimulated  into  its  healthy  aclion,  either  by 
additional  ftimulus  of  food  and  medicines,  or  by  the  accumula- 
tion of  fenforial  power  during  its  prefent  torpor.  In  inflamma- 
tory fevers  with  debility,  as  thofe  termed  putrid  fevers,  deliri- 
um is  fometimes,  as  well  as  ftupor,  rather  a  favourable  fign  ;  as 
lefs  fenforial  power  is  wafted  during  its  continuance  (fee  Clafs 
II.  i.  6.  8.),  and  the  conftitution  not  having  been  previoufly  ex- 
pofed to  excefs  of  ftimulation,  is  more  liable  to  be  excited  after 
previous  quiefcence. 

When  the  fum  of  general  pleafurable  fenfation  becomes  too 
great,  another  kind  of  delirium  fupervenes,  and  the  ideas  thus 
excited  are  miftaken  for  the  irritations  of  external  objefts  :  fuch 
a  delirium  is  produced  for  a  time  by  intoxicating  drugs,  as  fer- 
mented liquors,  or  opium  :  a  permanent  delirium  of  this  kind  is 
fometimes  induced  by  the  pleafures  of  inordinate  vanity,  or  by 
the  enthufiaftic  hopes  of  heaven.  In  thefe  cafes  the  power  of 
volition  is  incapable  of  exertion,  and  in  a  great  degree  the  exter- 
nal fenfes  become  incapable  of  perceiving  their  adapted  ftimuli, 
becaufe  the  whole  fenforial  power  is  employed  or  expended  on 
the  ideas  excited  by  pleafurable  fenfation. 

This  kind  of  delirium  is  diftinguifhed  from  that  which  at- 
tends the  fevers  above  mentioned  from  its  not  being  accompani- 
ed with  general  debility,  but  fimply  with  excefs  of  pleafurable 
fenfation  ;  and  is  therefore  in  forne  meafure  allied  to  madnefs 
or  to  reverie  ;  it  differs  from  the  delirium  of  dreams,  as  in  this 
the-power  of  volition  is  not  totally  fufpended,  nor  are  the  fenfes 
precluded  from  external  ftimulation  ;  there  is  therefore  a  degree 
of  confiftency3  in  this  kind  of  delirium,  and  a  degree  of  attentioa 


SECT.  XXXIII.  i.  5.       OF  SENSATION.  309 

to  external  objefts,  neither  of  which  exifts  in  the  delirium  of 
fevers  or  in  dreams. 

5.  It  would  appear,  that  the  vafcular  fyftems  of  other  animals 
are  lefs  liable  to  be  put  into  a£Hon  by  their  general  fum  of 
pleafurable  or  painful  fenfation  ;  and  that  the  trains  of  their 
ideas,  and  the  mufcular  motions  ufually  aflbciated  with  them, 
are  lefs  powerfully  conne&ed  than  in  the  human  fyftem.  For 
other  animals  neither  weep,  nor  fmile,  nor  laugh  ;  and  are 
hence  feldom  fubjeft  to  delirium,  as  treated  of  in  Se6i.  XVI.  on 
Inftinft.  Now  as  our  epidemic  and  contagious  difeafes  are 
probably  produced  by  difagreeable  fenfation,  and  not  fimply  by 
irritation  ;  there  appears  a  reafon  why  brute  animals  are  lefs  li- 
able to  epidemic  or  contagious  difeafes  ;  and  fecondly,  why  none 
of  our  contagions,  as  the  fmall-pox  or  meafles,  can  be  communi- 
cated to  them,  though  one  of  theirs,  viz.  the  hydrophobia,  as 
well  as  many  of  their  poifons,  as  thofe  of  fnakes  and  of  infefts, 
communicate  their  deleterious  or  painful  effeftsto  mankind. 

Where  the  quantity  of  general  painful  fenfation  is  too  great 
in  the  fyftem,  inordinate  voluntary  exertions  are  produced  either 
of  our  ideas,  as  in  melancholy  and  madnefs,  or  of  our  mufcles, 
as  in  convulfion.  From  thefe  maladies  alfo  brute  animals  are 
much  more  exempt  than  mankind,  owing  to  their  greater  inapti- 
tude to  voluntary  exertion,  as  mentioned  inSe&.XVI.on  Inftinft. 

II.  i.  When  any  moving  organ  is  excited  into  iuch  violent 
motions,  that  a  quantity  of  pleafurable  or  painful  fenfation  is 
produced,  it  frequently  happens  (but  not  always)  that  new  mo- 
tions of  the  affected  organ  are  generated  in  confequence  of  the 
pain  or  pleafure,  which  are  termed  inflammation. 

Thefe  new  motions  are  of  a  peculiar  kind,  tending  to  diftend 
the  old,  and  to  produce  new  fibres,  and  thence  to  elongate  the 
flraight  mufcles,  which  ferve  locomotion,  and  to  form  new  vef- 
fels  at  the  extremities  or  fides  of  the  vafcular  mufcles. 

2.  Thus  the  pleafurable  fenfations  produce  an  enlargement  of 
the  nipples  of  nurfes,  of  the  papillae  of  the  tongue,  of  the  penis, 
and  probably  produce  the  growth  of  the  body  from  its  embryon 
(tare  to  its  maturity ;  whilft  the  new  motions  in  confequence  of 
painful  fenfation,  with  the  growth  of  the  fibres  or  veflels,  which 
they  occafion,  are  termed  inflammation. 

Hence  when  the  ftraight  mufcles  are  inflamed,  part  of  their 
tendons  at  each  extremity  gain  new  life  and  fenfibility,  and  thus 
the  mufcle  is  for  a  time  elongated  ;  and  inflamed  bones  become 
fofr,  vafcular,  and  fenfible.  Thus  new  veflels  (hoot  over  the 
cornea  of  inflamed  eyes,  and  into  fcirrhous  tumours,  when  they 
become  inflamed  ;  and  hence  all  inflamed  parts  grow  together 
by  intermixture,  arid  inofculation  of  the  new  and  old  veflels, 

The 


3io  DISEASES          SECT.  XXXIII.  2. 3, 

The  heat  is  occafioned  from  the  increafed  fecretions  either  of 
mucus,  or  of  the  fibres,  which  produce  or  elongate  the  veflels. 
The  red  colour  is  owing  to  the  pellucidity  of  the  newly  formed 
veflels,  and  as  the  arterial  parts  of  them  are  probably  formed  be- 
fore  their  correfpondent  venous  parts. 

3.  Thefe  new  motions  are  excited  either  from  the  increafed 
quantity  of  fenfation  in  confequence  of  greater  fibrous  contrac*- 
tions,  or  from  increafed    fenfibility,  that  is,  from  the  increafed 
quantity  of  fenforial  power  in  the  moving  organ.      Hence  they 
are  induced    by  great  external  ftimuli,    as  by  wounds,  broken 
bones  ;  and   by  acrid  or   infectious   materials  ;  or  by  common 
ftimuli  on  thofe  organs,  which  have  been  fome  time  quiefcent  ; 
as  the  ufual  light  of  the  day  inflames  the  eyes  of  thofe,who  have 
been  confined  in  dungeons  ;  and  the  warmth  of  a  common  fire 
inflames  thole,  who  have  been  previoufly  expofed  to  much  cold. 

But  thefe  new  motions  are  never  generated  by  that  pain, 
which  ariies  from  defeft  of  flimulus,  as  from  hunger,  thirft, 
cold,  or  inanitions,  with  all  thofe  pains,  which  are  termed  ner- 
vous. Where  thefe  pains  exift,  the  motions  of  the  affe&ed  part 
are  leflened  ;  and  if  inflammation  fucceeds,  it  is  in  fome  diftant 
parts  ;  as  coughs  are  caufed  by  coldnefs  and  moifture  being  long 
applied  to  the  feet ;  or  it  is  in  confequence  of  the  renewal  of  the 
ftimulus,  as  of  heat  or  food,  which  excites  our  organs  into 
ftronger  adHon  after  their  temporary  quiefcence  ;  as  kibed  heels 
after  walking  in  fnow. 

4.  But  when  thefe  new  motions  of  the  vafcular  rnufcles  are 
exerted  with  greater  violence,  and  thefe  veflels  are  either  elonga- 
ted too  much  or  too  haftily,  a  new  material  is  fecreted  from  their 
extremities,  \vhich  is  of  various  kinds  according  to  the  peculiar 
animal  motions  of   this  new  kind  of  gland,  which  fecretes  it  ; 
fuch  is  the  pus    laudable  or  common  matter,  the  variolus  mat- 
ter, venereal  matter,  catarrhous  matter,  and  many  others. 

5.  Thefe  matters  are  the  prod u6l  of  an  animal  procefs  ;  they 
are  fecreted  or  produced  from  the  blood  by  certain  difeafed  mo- 
tions of  the  extremities  of  the  blood-veflels,  and  are  on  that  ac- 
count all  of  them  contagious  ;  for  if  a  portion  of  any  of  thefe 
is  tranfmitted  into  the  circulation,  or  perhaps  only  inierted  into 
the  fkin,  or  beneath  the  cuticle  of  a  healthy  perfon,  its  ftimulus 
in  a  certain  time  produces  the  fame  kind  of  morbid  motions,  by 
which  itfelf  was  produced  ;  and  hence  a  fimilar  kind  is  genera- 
ted.    See  Seft.  XXXIX.  6.  i. 

6.  It  is  remarkable,  that  many  of  thefe  contagious  matters  are 
capable  of  producing  a  fimilar  difeafe  but  once  ;  as  the  fmall- 
pox  and  meafles  ;  and  I  fuppofe  this  is  true  of  all  thofe  conta- 
gious difeafes,  which  are  fpontaneoufly  cured  by  nature  in  a  cer- 
tain 


SECT,  XXXIII.  a.  7>      OF  SENSATION.  3 1 1 

tain  time  ;  for  if  the  body  was  capable  of  receiving  the  difeafe  a 
fecond  time,  the  patient  muft  perpetually  infect  himfelf  by  the 
very  matter,  which  he  has  himfelf  produced,  and  is  lodged  about 
him  ;  and  hence  he  could  never  become  free  from  the  difeafe. 
Something  fimilar  to  this  is  feen  in  the  fecondary  fever  of  the 
confluent  fmall-pox  j  there  is  a  great  abforption  of  variolous 
matter,  a  very  minute  part  of  which  would  give  the  genuine 
fmall-pox  to  another  perfon  ;  but  here  it  only  ftimulates  the 
fyitem  into  common  fever ;  like  that  which  common  pus,  or 
any  other  acrid  material  might  occafion. 

7.  In  the  pulmonary  confumption,  where  common  matter  is 
daily  abforbed,  an  irritative  fever  only,  without  new  inflam- 
mation, is  generally  produced  ;  which  is  terminated  like  other 
irritative  fevers  by  fweats  or  loofe  (tools.  Hence  it  does  not 
appear,  that  this  abforbed  matter  always  a£ls  as  a  contagious  ma- 
terial producing  frefh  inflammation  or  newabfcefles.  Though 
there  is  reafon  to  believe,  that  the  firfl  time  any  common  matter 
is  abforbed,  it  has  this  effect,  but  not  the  fecond  time,  like  the 
variolous  matter  above  mentioned. 

This  accounts  for  the  opinion,  that  the  pulmonary  confump- 
tion is  fometimes  infectious,  which  opinion  was  held  by  the  an- 
cients, and  continues  in  Italy  at  prefent  ;  and  I  have  myfelf  feeii 
three  or  four  initances,  where  a  hufband  and  wife,  who  have 
flept  together,  and  have  thus  much  received  each  other's  breath, 
who  have  infected  each  other,  and  both  died  in  confequence  of 
the  original  taint  of  only  one  of  them.  This  alfo  accounts  for 
the  abfcefles  in  various  parts  of  the  body,  that  are  fometimes 
produced  after  the  inoculated  fmall-pox  is  terminated  ;  for  this 
fecond  abforption  of  variolous  matter  ads  like  common  matter, 
and  produces  only  irritative  fever  in  thofe  children,  whole  confti- 
tutions  have  already  experienced  the  abforption  of  common  mat- 
ter ;  and  inflammation  with  a  tendency  to  produce  new  abfcefles 
in  thofe,  whofe  confutations  have  not  experienced  the  abforp- 
tions  of  common  matter. 

It  is  probable,  that  more  certain  proofs  might  have  been  found 
to  (hew,  that  common  matter  is  infectious  the  firil  time  it  is 
abforbed,  tending  to  produce  fimilar  abfcefles,  but  not  the  fec- 
ond time  of  its  abforption,  if  this  fubject  had  been  attended  to. 

8  Thefe  contagious  difeafes  are  very  numerous,  as  the 
plague,  fmall-pox,  chicken  pox,  meafles,  fcarlet-fever,  pemphi- 
gus, catarrh,  chin-cough,  venereal  difeafe,  itch,  trichoma,  tinea. 
The  infections  material  docs  not  feem  to  be  diflblved  by  the  air, 
but  only  mixed  with  it  perhaps  in  fine  powder,  which  foon  fub- 
(ides  ;  fince  many  of  thefe  contagious  can  only  be  received  by 
aftual  contact  *,  and  others  of  them  only  at  fmall  diltances  from 

the 


3 iz  DISEASES.        SECT.  XXXIII.  2.9, 

the  infefted  perfon  ;  as  is  evident  from  many  perfons  having 
been  near  patients  of  the  fmall-pox  without  acquiring  the 
difeafe. 

The  reafon,  why  many  of  thefe  difeafes  are  received  but  once, 
and  others  repeatedly,  is  not  well  underftood  ;  it  appears  to  me 
that  the  conilitution  becomes  fo  accuftomed  to  the  ftimuli  of 
thefe  infeftious  materials,  by  having  once  experienced  them, 
that  though  irritative  motions,  as  hectic  fevers,  may  again  be 
produced  by  them,  yet  no  fenfation,  and  in  confequence  no 
general  inflammation  fucceeds  •,  as  difagreeable  fmells  or  taftes 
by  habit  ceafe  to  be  perceived  ;  they  continue  indeed  to  excite 
irritative  ideas  on  the  organs  of  fenfe,  but  thefe  are  not  fucceed* 
ed  by  fenfation. 

There  are  many  irritative  motions,  which  were  at  firft  fuc- 
ceeded  by  fenfation,  but  which  by  frequent  repetition  ceafe  to  ex- 
cite fenfation,  as  explained  in  Sect.  XX.  on  Vertigo.  And,  that 
this  circumftance  exifts  in  refpett  to  infectious  matter  appears 
from  a  known  fact •,  that  nurfes,  who  have  had  the  fmail-pox 
are  liable  to  experience  fmall  ulcers  on  their  arms  by  the  contact 
of  variolous  matter  in  lifting  their  patients  ;  and  that  when  pa- 
tients, who  have  formerly  had  the  fmall-pox  have  been  inocula- 
ted in  the  arm,  a  phlegmon,  or  inflamed  fore,  has  fucceeded,  but 
no  fubfequent  fever.  Which  (hews,  that  the  contagious  matter 
of  the  fmall-pox  has  not  loft  its  power  of  itimulatinglthe  part  it 
is  applied  to,  but  that  the  general  fyftem  is  not  affected  in  con- 
fequence. See  Section  XIL  7.  6.  XIX.  10. 

9,  From  the  accounts  of  the  plague,  virulent  catarrh,  and 
putrid  dyfentery,  it  feems  uncertain,  whether  thefe  difeafes  are 
experienced  more  than  once ;  but  the  venereal  difeafe  and  itch 
are  doubtlefs  repeatedly  infectious ;  and  as  thefe  difeafes  are 
never  cured  fpontaneoufly,  but  require  medicines,  which  act 
without  apparent  operation,  fome  have  fufpected,  that  the  con- 
tagious material  produces  fimilar  matter  rather  by  a  chemical 
change  of  the  fluids,  than  by  an  animal  procefs  ;  and  that  the  fpe- 
cific  medicines  deftroy  their  virus  by  chemically  combining  with 
it.  This  opinion  is  fuccefsfully  combatted  by  Mr.  Hunter,  in 
his  Treatife  on  Venereal  Difeafe,  Part  I.  c.  i. 

But  this  opinion  wants  the  fupport  of  analogy,  as  there  is  no 
known  procefs  in  animal  bodies,  which  is  purely  chemical,  not 
even  digeftion ;  nor  can  any  of  thefe  matters  be  produced  by 
chemical  procefles.  Add  to  this,  that  it  is  probable,  that  the 
infects,  obferved  in  the  puftules  of  the  itch,  and  in  the  (tools  of 
dy  fenteric  patients,  are  the  confequences,  and  not  the  caufes  of 
thefe  difeafes.  And  that  the  fpecific  medicines,  which  cure  the 
itch,  and  lues  venerea,  as  brimftone  and  mercury,  act  only  by  in- 

creafing 


SECT.  XXXIII.  2. 9.      OF  SENSATION.  313 

creating  the  abforption  of  the  matter  in  the  ulcufcles  of  thofe 
difeafes,  and  thence  difpofing  them  to  heal ;  which  would  other- 
wife  continue  to  fpread. 

Why  the  venereal  difeafe,  and  itch,  and  tinea,  or  fcald  head, 
are  repeatedly  contagious,  while  thofe  contagions  attended  with 
fever  can  be  received  but  once,  feems  to  depend  on  their  being 
rather  local  difeafes  than  univerfal  ones,  and  are  hence  not  at- 
tended with  fever,  except  the  purulent  fever  in  their  laft  ftages, 
when  the  patient  is  deftroyed  by  them.  On  this  account  the 
whole  of  the  fyftem  does  not  become  habituated  to  thefe  morbid 
actions,  fo  as  to  ceafe  to  be  affefted  with  fenfation  by  a  repetition 
of  the  contagion.  Thus  the  contagious  matter  of  the  venereal 
difeafe,  and  of  the  tinea,  affefts  the  lymphatic  glands,  as  the  in- 
guinal glands,  and  thofe  about  the  roots  of  the  hair  and  neck, 
where  it  is  arrefted,  but  does  not  feem  to  affedl  the  blood-veflels, 
fince  no  fever  enfues. 

Hence  it  would  appear  that  thefe  kinds  of  contagion  are  prop- 
agated not  by  means  of  the  circulation,  but  by  fympathy  of  dif- 
tant  parts  with  each  other  ;  fince  if  a  diftant  part,  as  the  palate, 
(hould  be  excited  by  fenfitive  affociation  into  the  fame  kind  of 
motions,  as  the  parts  originally  affedled  by  the  contadt  of  infec- 
tious matter  ;  that  diftant  part  will  produce  the  fame  kind  of 
infectious  matter  ;  for  every  fecretion  from  the  blood  is  formed 
from  it  by  the  peculiar  motions  of  the  fine  extremities  of  the 
gland,  which  fecretes  it ;  the  various  fecreted  fluids,  as  the  bile, 
feliva,  gaftric  juice,  not  previoufly  exifling,  as  fuch,  in  the  blood- 
veflels. 

And  this  peculiar  fympathy  between  the  genitals  and  the 
throat,  owing  to  fenfitive  aflbciation,  appears  not  only  in  the 
production  of  venereal  ulcers  in  the  throat,  but  in  a  variety  of 
other  inftances,  as  in  the  mumps,  in  the  hydrophobia,  fome 
coughs,  ftrangulation,  the  production  of  the  beard,  change  of 
voice  at  puberty,  which  are  further  defcribed  in  Clafs  IV.  i.  2.  7. 

To  evince  that  the  produdion  of  fuch  large  quantities  of  con- 
tagious matter,  as  are  feen  in  fome  variolous  patients,  fo  as  to 
cover  the  whole  (kin  almoft  with  puftules,  does  not  arife  from 
any  chemical  fermentation  in  the  blood,  but  that  it  is  owing  to 
morbid  motions  of  the  fine  extremities  of  the  capillaries,  or 
glands,  whether  thefe  be  ruptured  or  not,  appears  from  the  quan- 
tity of  this  matter  always  correfponding  with  the  quantity  of  the 
fever ;  that  is,  with  the  violent  exertions  of  thofe  glands  and 
capillaries,  which  are  the  terminations  of  the  arterial  fyftem. 

The  truth  of  this  theory  is  evinced  further  by  a  circumftance 
obferved  by  Mr.  J.  Hunter,  in  his  Treatife  on  Venereal  Difeafe  ; 
that  in  a  patient,  who  was  inoculated  for  the  fmall-pox,  and 

VOL.  I.  R  R  who 


DISEASES         SECT.  XXXIII.  2.  9. 

who  appeared  afterwards  to  have  been  pevioufly  infefted  with 
the  meafles,  the  progrefs  of  the  fmall-pox  was  delayed  till  the 
meafles  had  run  their  courfe,  and  that  then  the  fmall-pox  went 
through  its  ufual  periods. 

Two  fimilar  cafes  fell  under  my  care,  which  I  (hall  here  re- 
late, as  it  confirms  that  of  Mr.  Hunter,  and  contributes  to  illuf- 
trate  this  part  of  the  theory  of  contagious  difeafes,  I  have  tranf- 
cribed  the  particulars  from  a  letter  of  Mr.  Lightwood,  of  Yoxal, 
the  furgeon  who  daily  attended  them,  and  at  my  requeft,  after  I 
had  feen  them,  kept  a  kind  of  journal  of  their  cafes. 

Mifs  H.  and  Mifs  L  two  fitters,  the  one  about  four  and  the 
other  about  three  years  old,  were  inoculated  Feb.  7,  1791.  On 
the  i  oth  there  was  a  rednefs  on  both  arms  difcernible  by  a  glafs. 
On  the  nth  their  arms  were  fo  much  inflamed,  as  to  leave  no 
doubt  of  the  infe£Uon  having  taken  place.  On  the  1 2th  ieis 
appearance  of  inflammation  on  their  arms.  In  the  evening  Mifs 
L.  had  an  eruption,  which  refembled  the  meafles.  On  the  i3th 
the  eruption  on  Mifs  L.  was  very  full  on  the  face  and  breaft, 
like  the  meafles,  with  confiderabie  fever.  It  was  now  known, 
that  the  meafles  were  in  a  farm  houfe  in  the  neighbourhood. 
Mifs  H/s  armlefs  inflamed  than  yefterday.  On^the  I4th  Mifs 
L.'s  fever  great,  and  the  eruption  univerfal.  The  arm  appears 
to  be  healed.  Mifs  H.'s  arm  fomewhat  redder.  They  were 
now  put  into  feparate  rooms.  On  the  1 5th  Mifs  L.'s  arms  as 
yeRerday.  Eruption  continues.  Mils  H/s  arms  have  varied 
but  little.  1 6th,  the  eruptions  on  Mifs  L  are  dying  away,  her 
fever  gone.  Begins  to  have  a  little  rednefs  in  one  arm  at  the 
place  of  inoculation.  Mifs  H.'s  arms  get  redder,  but  (he  has  no 
appearance  of  complaint.  2oth,  Mifs  L's  arms  have  advanced 
flowly  till  this  day,  and  now  a  few  puftules  appear.  Mils  H.'s 
arm  has  made  little  progrefs  from  the  i6th  to  this  day,  and  now 
{he  has  fome  fever.  21  ft,  Mifs  L.  as  yefterday.  Mifs  H.  has 
much  inflammation,  and  an  increafe  of  the  red  circle  on  one  arm 
to  the  fize  of  half-a-crown,  and  had  much  fever  at  night,  with 
fetid  breath.  22d,  MifsL  's  puftules  continue  advancing.  Mifs 
H.'s  inflammation  of  her  arm  and  red  circle  increafes.  A  few 
red  fpots  appear  in  different  parts  with  fome  degree  of  fever  this 
morning.  23d,  Mifs  L.  has  a  larger  crop  of  puftules.  Mifs 
H.  hasfmall  puftules  and  great  inflammation  of  her  arms,  with 
but  one  puftule  likely  to  fuppurate.  After  this  day  they  gradu- 
ally got  well,  and  the  puftules  difappeared. 

In  one  of  thefe  cafes  the  meafles  went  through  their  common 
courfe  with  milder  fymptoms  than  ufual,  and  in  the  other  the 
meafly  contagion  feemed  juft  fufficient  to  ftop  the  progreis  of 
variolous  contagion,  but  without  itfelf  throwing  the  conftitution 

into 


SECT.  XXXIII.  2.  10.        OF  SENSATION.  315 

into  any  diforder.  At  the  fame  time  both  the  meafles  and  fmall- 
pox  feem  to  have  been  rendered  milder.  Does  not  this  give  an 
idea,  that  if  they  were  both  inoculated  at  the  fame  time,  that 
neither  of  them  might  affeft  the  patient  ? 

From  thefe  cafes  I  contend,  that  the  contagious  matter  of 
thefe  difeafes  does  not  affe<ft  the  conftitution  by  a  fermentation, 
or  chemical  change  of  the  blood,  becaufethen  they  mud  have 
proceeded  together,  and  have  produced  a  third  fomething,  not 
exactly  fimilar  to  either  of  them ;  but  that  they  produce  new- 
motions  of  the  cutaneous  terminations  of  the  blood  veflels, 
which  for  a  time  proceed  daily  with  increafing  aftiviry,  like 
fome  paroxyfms  of  fever,  till  they  at  length  fecrete  or  form  a 
fimiiar  poifon  by  thefe  unnatural  adlions. 

Now  as  in  the  meafles  one  kind  of  unnatural  motion  takes 
place,  and  in  the  fmall-pox  another  kind,  it  is  eafy  to  conceive, 
that  thefe  different  kinds  of  morbid  motions  cannot  exift  togeth- 
er ;  and  therefore,  that  that  which  has  firft  begun  will  continue 
till  the  fyftem  becomes  habituated  to  the  (limulus  which  occa- 
fions  it,  and  has  ceafed  to  be  thrown  into  aftion  by  it ;  and  then 
the  other  kind  of  ftimulus  will  in  its  turn  produce  fever,  and 
new  kinds  of  motions  peculiar  to  itfelf. 

10.  On  further  considering  th^aftion  of  contagious  matter, 
fince  the  former  part  of  this  work  was  fent  to  the  prefs  ;  where 
I  have  afferted,  in  Seft.  XXII.  4.  3.  that  it  is  probable,  that  the 
variolous  matter  is  diffufed  through  the  blood  ;  I  prevailed  on 
my  friend  Mr.  Power,  furgeon  at  Bofworth,  in  Leicefterfhire,  to 
try,  whether  the  fmali-pox  could  be 'inoculated  by  ufing  the 
blood  of  a  variolous  patient  inftead  of  the  matter  from  the 
puftules  ;  as  I  thought  fuch  an  experiment  might  throw  fome 
light  at  lead  on  this  interefting  fubjedt.  The  following  is  an 
extraft  from  his  letter  : — 

"March  n,  1793  I  inoculated  two  children,  who  had  not 
had  the  fmall-pox,  with  blood  ;  which  was  taken  from  a  patient 
on  the  fecond  day  after  the  eruption  commenced,  and  before  it 
was  completed,  And  at  the  fame  time  I  inoculated  myfelf  with 
blood  from  the  fame  perfon,  in  order  to  compare  the  appearance, 
which  might  arife  in  a  perfon  liable  to  receive  the  infection,  and 
in  one  not  liable  to  receive  it.  On  the  fame  day  I  inoculated 
from  other  children  liable  to  receive  the  infection  with  blood 
taken  from  another  perfon  on  the  fourth  day  after  the  com- 
mencement of  the  eruption.  The  patients  from  whom  the  blood 
was  taken  had  the  difeafe  mildly,  but  had  the  moil  puftules  of 
any  I  could  feletl  from  twenty  inoculated  patients  ;  and  as 
much  of  the  blood  was  infmuated  under  the  cuticle,  as  I  could 
introduce  by  elevating  the  fkin  without  drawing  blood  •,  and 

three 


316  DISEASES        SECT.  XXXIH.  2.  10- 

three  or  four  fuch    pun&ures  were  made  in  each  of  their  arms, 
and  the  blood  was  ufed  in  its  fluid  ftate. 

«  As  the  appearances  in  all  thefe  patients,  as  well  as  in  myfelf, 
were  fimilar,  I  fhall  only  mention  them  in  general  terms. 
March  13.  A  flight  fubcuticular  difcoloration,  with  rather  a 
livid  appearance,  without  forenefs  or  pain,  was  vifible  in  them 
all,  as  well  as  in  my  own  hand.  15.  The  difcoloration  fome- 
what  lefs,  without  pain  or  forenefs.  Some  patients  inoculated 
on  the  fame  day  with  variolous  matter  have  confiderable  inflame 
mation.  1 7.  The  difcoloration  is  quite  gone  in  them  all,  and 
from  my  own  hand,  a  dry  mark  only  remaining.  And  they 
were  all  inoculated  on  the  1 8th,  with  variolous  matter,  which 
produces  the  difeafe  in  them  all." 

Mr.  Power  afterwards  obferves,  that,  as  the  patients  from 
whom  the  blood  was  taken  had  the  difeafe  mildly,  it  may  be 
fuppofed,  that  though  the  contagious  matter  might  be  mixed 
with  the  blood,  it  might  dill  be  in  too  dilute  a  ftate  to  convey 
the  infeclion  ;  but  adds  at  the  fame  time,  that  he  has  diluted 
recent  matter  with  at  lead  five  times  its  quantity  of  water,  and 
which  has  ftill  given  the  infection  5  though  he  has  fometimes 
diluted  it  fo  far  as  to  fail. 

The  following  experiments  were  inflituted  at  my  requeft  by 
my  friend  Mr.  Hadley,  furgeon  in  Derby,  to  afcertain  whether 
the  blood  of  a  perfon  in  the  fmall-pox  be  capable  of  communi- 
eating  the  difeafe.  "Experiment  i  ft,  October  i8th,  1793.  * 
took  fome  blood  from  a  vein  in  the  arm  of  a  perfon  who  had 
the  fmali-poxj  on  the  fecond  day  of  the  eruption,  and  introdu- 
ced a  fmall  quantity  of  it  immediately  with  the  point  of  a  lancet 
between  the  fcarf  and  true  fkin  of  the  right  arm  of  a  boy  nine 
years  old  in  two  or  three  different  places  ;  the  other  arm  was 
Inoculated  with  variolous  matter  at  the  fame  time. 

"  ipth.  The  punctured  parts  of  the  right  arm  were  furround- 
ed  with  fome  degree  of  fubcuticular  inflammation.  2oth  The 
inflammation  more  confiderable,  with  a  flight  degree  of  itching, 
but  no  pain  upon  preflure.  21  ft.  Upon  examining  the  arm 
this  day  with  a  lens,  I  found  the  inflammation  lefs  extenfive, 
and  the  rednefs  changing  to  a  deep  yellow  or  orange -colour. 
22d.  Inflammation  nearly  gone.  23d.  Nothing  remained,  except 
a  flight  difcoloration  and  a  little  fcurfy  appearance  on  the  punc- 
tures. At  the  fame  time  the  inflammation  of  the  arm  inoculated 
with  variolous  matter  was  increafing  faft,  and  he  had  the  difeafe 
mildly  at  the  ufual  time. 

«  Experiment  2d.  I  inoculated  another  child  at  the  fame 
time  and  in  the  fame  manner,  with  blood  taken  on  the  firft  day 
of  the  eruption  ;  but  as  the  appearance  and  effedi  were  fimilar 

to 


SECT.  XXXIII.  2.  10.      OF  SENSATION.  317 

to  thofe  in  the  preceding  experiment,  I  (hall  not   relate  them 
minutely. 

"  Experiment  3d  October  2oth.  Blood  was  taken  from  a 
perfon  who  had  the  ftnall-pox,  on  the  third  day  of  the  eruption, 
and  on  the  fixth  from  the  commencement  of  the  eruptive  fever, 
I  introduced  fome  of  it  in  its  fluid  (late  into  both  arms  of  a  boy 
feven  years  old.  21.  There  appeared  to  be  fome  inflammation 
under  the  cuticle,  where  the  punctures  were  made.  22d.  In- 
flammation more  confiderable.  23d.  On  this  day  the  inflamma- 
tion was  fomewhat  greater,  and  the  cuticle  rather  elevated. 

"  24th.  Inflammation  much  lefs,  and  only  a  brown  or  orange- 
colour  remained.  25th.  Scarely  any  difcoloration  left.  On 
this  day  he  was  inoculated  with  variolous  matter,  the  progrefs  of 
the  infection  went  on  in  the  ufual  way,  and  he  had  the  fmall- 
pox  very  favourably. 

"  At  this  time  I  was  requefted  to  inoculate  a  young  pefojn, 
who  was  thought  to  have  had  the  fmall-pox,  but  his  parents  were 
not  quite  certain  •,  in  one  arm  I  introduced  variolous  matter,  and 
in  the  other  blood,  taken  as  in  experiment  3d.  On  the  fecond 
day  after  the  operation,  the  punctured  parts  were  inflamed, 
though  I  think  the  arm  in  which  I  had  inferted  variolous  mat- 
ter was  rather  more  fo  than  the  other.  On  the  third  the  inflam- 
mation was  increafed,  and  looked  much  the  fame  as  in  the  pre- 
ceding experiment.  4th.  The  inflammation  was  much  dimin- 
ifhed,  and  on  the  5th  almoftgone.  He  was  expofed  at  the  fame 
time  to  the  natural  infection,  but  has  continued  perfectly  well, 

"  I  have  frequently  obferved  (and  believe  moft  practitioners 
have  done  the  fame),  that  if  variolous  matter  be  inferted  in  the 
arm  of  a  perfon  who  has  previouily  had  the  fmall-pox,  the  in- 
flammation on  the  fecond  or  third  day  is  much  greater,  than  if 
they  had  not  had  the  difeafe,  but  on  the  fourth  or  fifth  it  dif- 
appears. 

"  On  the  23d  I  introduced  blood  into  the  arms  of  three  more 
children,  taken  on  the  third  and  fourth  days  of  the  eruption. 
The  appearances  were  much  the  fame  as  mentioned  in  experi- 
ments firft  and  third.  -They  were  afterwards  inoculated  with 
variolous  matter,  and  had  the  difeafe  in  the  regular  way. 

"  The  above  experiments  were  made  with  blood  taken  from 
a  fmall  vein  in  the  hand  or  foot  of  three  or  four  different  patients, 
whom  I  had  at  that  time  under  inoculation.  They  were  fele&- 
edfrom  160,  as  having  the  greateft  number  of  puftules.  The 
part  was  wafhed  with  warm  water  before  the  blood  was  taken, 
to  prevent  rhe,poffibility  of  any  matter  being  mixed  with  it  from 
the  fuvface." 

Shall  we  conclude  from  hence,  that  the  variolous  matter  never 

enters 


3 1 8  DISEASES          SECT.  XXXIII.  2.  le. 

enters  the  blood- veffels  -9  but  that  the  morbid  motions  of  the  vef- 
fels  of  the  (kin  around  the  infertion  of  it  continue  to  increafe  in 
a  larger  and  larger  circle  for  fix  or  feven  days  •,  that  then  their 
quantity  of  morbid  a£lion  becomes  great  enough  to  produce  a 
fevc-r-fit,  and  to  affeft  the  ftomach  by  aflbciation  of  motions  ? 
and  finally,  that  a  iecond  aflbciation  of  motions  is  produced  be- 
tween the  ftomach  and  the  other  parts  of  the  fkin,  inducing 
them  into  morbid  actions  fimilar  to  thofe  of  the  circle  round 
the  infertion  of  the  variolous  matter  ?  Many  more  experiments 
and  observations  are  required  before  this  important  queflion  can 
be  fat  isfadl  only  anfwered. 

It  may  be  adduced,  that  as  the  matter  inferted  into  the  fkin  of 
the  arm  frequently  fwells  the  lymphatic  in  the  axilla,  that  in  that 
circumstance  it  feems  to  be  there  arrefted  in  its  progrefs,  and 
cannot  be  imagined  to  enter  the  blood  by  that  lymphatic  gland 
till  the  fwelling  of  it  fubfides.  Some  other  phenomena  of  the 
diieafe  are  more  eafily  reconcileable  to  this  theory  of  fympathet- 
ic  motions  than  to  that  of  abforption  ;  as  the  time  taken  up  be- 
tween the  infertion  of  the  matter,  and  the  operation  of  it  on  the 
fyftenij  as  mentioned  above.  For  the  circle  round  the  infertion 
is  feen  to  increafe,  and  to  inflame  ;  and  I  believe,  undergoes  a 
kind  of  diurnal  paroxyfm  of  torpor  and  palenefs  with  a  fucceed- 
ing  increafe  of  action  and  colour,  like  a  topical  fever-fit. 
Whereas  if  the  matter  is  conceived  to  circulate  for  fix  or  feven 
days  with  the  blood,  without  producing  diforder,  it  ought  to  be 
rendered  milder,  or  the  blood  veflels  more  familiarized  to  its 
-acrimony. 

It  is  much  eafier  to  conceive  from  this  doftrine  of  aflbciated 
or  fympathetic  motions  of  diftant  parts  of  the  fyflem,  how  it 
happens,  that  the  vaiiolous  infection  may  be  received  but  once, 
as  before  explained  ;  than  by  fuppofing,  that  a  change  is  effect- 
ed in  the  mafs  of  blood  by  any  kind  of  fermentative  procefs. 

The  curious  circumftance  of  the  two  contagions  of  fmall-pox 
and  meafles  not  acting  at  the  fame  time,  but  one  of  them  reding 
or  iufpending  its  aftion  till  that  of  the  other  ceafes,  may  be  much 
eafiev  explained  from  fympatht-tic  or  aflbciated  a&ionsof  the  in- 
feded  part  with  other  parts  of  the  fyftem,  than  it  can  from  fup- 
pofing the  two  contagions  to  enter  the  circulation. 

The  fkin  of  the  face  is  fubjed  to  more  frequent  viciflitudes  of 
heat  and  cold,  from  its  expofure  to  the  open  air,  and  is  in  con- 
fequence  more  liable  to  fenfitive  aflbciation  with  the  ftomach 
than  any  other  part  of  the  furface  of  the  body,  becaufe  their  ac- 
tions have  been  .more  frequently  thus  aflbciated.  Thus  in  a 
furfeit  from  drinking  cold  water,  when  a  perfon  is  very  hot  and 
fatigued,  an  eruption  is  liable  to  appear  on  the  fae«  in  confe- 

quence 


SECT.  XXXIII.  3.  i.       OF  SENSATION. 

quence  of  this  fympathy.  In  the  fame  manner  the  rofy  eruption 
on  the  faces  of  drunkards  more  probably  arifes  from  the  fympathy 
of  the  face  with  the  ftomach,  rather  than  between  the  face  and 
the  liver,  as  is  generally  fuppofed. 

This  fympathy  between  the  ftomach  and  the  Ikin  of  the  face 
is  apparent  in  the  eruption  of  the  fmall-pox  ;  fmce,  where  the  dif- 
eafe  is  in  coniiderable  quantity,  the  eruption  on  the  face  firft: 
fucceeds  the  ficknefs  of  the  ftomach.  In  the  natural  difeafe  the 
ftomach  feems  to  be  frequently  primarily  affected,  either  alone 
or  along  with  the  tonfils,  as  the  matter  feems  to  be  only  diffufed 
in  the  air,  and  by  being  mixed  with  the  faliva,  or  mucus  of  the 
tonfils,  to  be  fwallowed  into  the  ftomach. 

After  fome  days  the  irritative  circles  of  motions  become  dif- 
ordered  by  this  new  ftimulus,  which  acts  upon  the  mucous  li- 
ning of  the  ftomach  •,  and  ficknefs,  vertigo,  and  diurnal  fever 
fucceed.  Thefe  difordered  irritative  morions  become  daily  in- 
creafed  for  two  or  three  days,  and  then  by  their  increafed  action 
certain  fenfitive  motions,  or  inflammation,  is  produced,  and  at 
the  next  cold  fit  of  fever,  when  the  ftomach  recovers  from  its 
torpor,  an  inflammation  of  the  external  (kin  is  formed  in  points 
(which  afterwards  fuppurate),  by  fenfitive  aTociation,  in  the 
fame  manner  as  a  cough  is  produced  in  confequence  of  expofing 
the  feet  to  cold,  as  defcribed  in  Seel.  XXV.  i.  i.  and  Clafs  IV. 
2.  1.7.  If  the  inoculated  (kin  of  the  arm,  as  far  as  it  appears 
inflamed,  was  to  be  cut  out,  or  deftroyed  by  cauftic,  before  the 
fever  commenced,  as  fuppofe  on  the  fourth  day  after  inoculation, 
would  this  prevent  the  difeafe  ?  as  it  is  fuppofed  to  prevent  the 
hydrophobia. 

III.  i.  Where  the  new  veflels,  and  enlarged  old  ones,  which 
conftitute  inflammation,  are  not  fo  haftily  diftended  as  to  burft, 
and  form  a  new  kind  of  gland  for  the  fecretion  of  matter,  as 
above  mentioned  ;  if  fuch  circumftances  happen  as  diminifh  the 
painful  fenfation,  the  tendency  to  growth  ceafes,  and  by  and  by 
an  abforption  commences,  not  only  of  the  fuperabundant  quan- 
tity of  fluids  depofited  in  the  inflamed  part,  but  of  the  folids 
likewife,  and  this  even  of  the  hardeft  kind 

Thus  during  the  growth  of  the  fecond  fet  of  teeth  in  children, 
the  roots  of  the  firft  fet  are  totally  abforbed,  till  at  length  noth- 
ing of  them  remains  but  the  crown  ;  though  a  few  weeks  before, 
if  they  are  drawn  im maturely,  their  roots  are  found  complete. 
Similar  to  this  Mr  Hunter  has  observed,  that  where  a  dead 
piece  of  bone  is  to  exfoliate,  or  to  feparate  from  a  living  one, 
the  dead  part  does  not  putrify,  but  remains  perfectly  found, 
while  the  furface  of  the  living  part  of  the  bone,  which  is  in  con- 
tact with  the  dead  part,  becomes  abforbed,  and  thus  effects  its 

feparation. 


320  DISEASES         SECT.  XXXIIL  3. 2. 

reparation.  Med.  Comment.  Edinb.  V.  1.425.  In  the  fame 
manner  the  calcareous  matter  of  gouty  concretions,  the  coagula- 
ble  lymph  depofited  on  inflamed  membranes  in  rheumatifm  and 
extravafated  blood  become  abforbed  j  which  are  all  as  folid  and  as 
indiflbluble  materials  as  the  new  veflels  produced  in  inflammation. 

This  abforption  of  the  new  veflels  and  depofited  fluids  of  in- 
flamed parts  is  called  refolution  :  it  is  produced  by  firft  ufing 
fuch  internal  means  as  decreafe  the  pain  of  the  part,  and  in  con- 
fequence  its  new  motions,  as  repeated  bleedings,  cathartics,  dilu- 
ent potations,  and  warm  bath. 

After  the  veflels  are  thus  emptied,  and  the  abforption  of  the 
new  veflels  and  depofited  fluids  is  evidently  begun,  it  is  much 
promoted  by  flimulating  the  part  externally  by  folutions  of  lead, 
or  other  metals,  and  internally  by  the  bark,  and  fmall  dofes  of 
opium.  Hence  when  an  opthalmy  begins  to  become  paler, 
any  acrid  eye  water,  as  a  folution  of  fix  grains  of  white  vitriol 
in  an  ounce  of  water,  haflens  the  abforption,  and  clears  the  eye 
in  a  very  fhort  time.  But  the  fame  application  ufed  a  few  days 
fooner  would  have  increafed  the  inflammation.  Hence  after 
evacuation  opium  in  fmall  dofes  may  contribute  to  promote  the 
abforption  of  fluids  depofited  on  the  brain,  as  obferved  by  Mr. 
Bromfield  in  his  treatife  of  furgery. 

2.  Where  an  abfcefs  is  formed  by  the  rupture  of  thefe  new 
veflels,  the  violence  of  inflammation  ceafes,  and  a  new  gland 
feparates  a  material  called  pus  :  at  the  fame  time  a  leis  degree 
of  inflammation  produces  new  veflels  called  vulgarly  proud 
flefh  ;  which,  if  no  bandage  confines  its  growth,  nor  any  other 
circumftance  promotes  abforption  in  the  wound,  would  rife  to  a 
great  height  above  the  ufual  fize  of  the  part. 

Hence  the  art  of  healing  ulcers  confifts  in  producing  a  ten- 
dency to  abforption  in  the  wound  greater  than  the  depofition. 
Thus  when  an  ill-conditioned  ulcer  feparates  a  copious  and  thin 
difcharge,  by  the  ufe  of  any  ftimulus,  as  of  falts  of  lead,  or  mer- 
cury, or  copper  externally  applied,  the  difcharge  becomes  dimin- 
ifhed  in  quantity,  and  becomes  thicker,  as  the  thinner  parts  are 
firft  abforbed. 

To  which  in  ulcerations  of  the  lungs,  and  in  fome  catarrhs,  a 
pertinacious  abftinence  from  fluids  has  been  recommended*  as 
well  as  in  dropfies,  and  diabetes,  which  in  the  former  as  well  as 
in  the  latter,  may  have  a  tendency  to  increafe  abforpcion  from 
the  affedled  parts,  and  may  thus  be  moderately  employed  with 
advantage  ;  but  may  have  a  dangerous  tendency  if  ufed  to  an 
extreme,  by  inducing  too  great  third,  and  confequent  fever  or 
inflammation.  Lower  de  Catarrhis.  Davidfon  on  Pulmonary 
Syftem.  Rollo  on  Diabetes. 

But 


SECT.  XXXIII  3.  3.      v'OF  SENSATION.  321 

But  nothing  fo  much  contributes  to  increafe  the^abforption  in. 
a  wound  as  covering  the  whole  limb  above  the  fore  with  a  band- 
age, which  fhould  be  fpread  with  fome  plafter,  as  with  emplaf- 
trum  de  minio,  to  prevent  it  from  flipping.  By  this  artificial 
tightnefs  of  the  (kin,  the  arterial  pulfations  aft  with  double  their 
ufu  il  power  in  promoting  the  afcending  current  of  the  fluid  in 
the  valvular  lymphatics. 

Internally  the  abforption  from  ulcers  (hould  be  promoted  firft 
by  evacuation,  then  by  opium,  bark,  mercury,  fteel. 

3.  Where  the  inflammation  proceeds  with  greater  violence 
or  rapidity,  that  is,  when  by  the  painful  fenfation  a  more  inor- 
dinate activity  of  the  organ  is  produced,  and  by  this  great  activity 
an  additional  quantity  of  painful  fenfation  follows  in  anincreafing 
ratio,  till  the  whole  of  the  fenforial  power,  or  fpirit  of  animation, 
in  the  part  becomes  exhaufted,  a  mortification  enfues,  as  in  a 
carbuncle,  in  inflammations  of  the  bowels,  in  the  extremities  of 
old  people,  or  in  the  limbs  of  thofe  who  are  brought  near  a 
fire  after  having  been  much  benumbed  with  cold.  And  from 
hence  it  appears,  why  weak  people  are  more  fubje£l  to  mortifi- 
cations than  (Irong  ones,  and  why  in  weak  perfons  lefspain  will 
produce  mortification,  namely,  becaufe  the  fenforial  power  is 
fooner  exhaufted  by  an  excefs  of  aftivity.  I  remember  feeing 
a  gentleman  who  had  the  preceding  day  travelled  two  itages  in 
a  chaife  with  what  he  termed  a  bearable  pain  in  his  bowels  ; 
which  when  I  faw  him  had  ceafed  rather  fuddenly,  and  without 
a  paflage  through  him  ;  his  pulfe  was  then  weak,  though  not 
very  quick;  but  as  nothing  which  he  fwallowed  would  continue 
in  his  ftomach  many  minutes,  I  concluded  that  the  bowel  was 
mortified  ;  he  died  on  the  next  day.  It  is  ufual  for  patients 
finking  under  the  fmall-pox  with  mortified  puftules,  and  with 
purple  fpots  intermixed,  to  complain  of  no  pain,  but  to  fay 
they  are  pretty  well  to  the  bift  moment. 


Recapitulation. 

IV.  When  the  motions  of  any  part  of  the  fyftem,  in  confe- 
quence  of  previous  torpor,  are  performed  with  more  energy 
than  in  the  irritative  fevers,  a  dif agreeable  fenation  is  produced', 
and  new  actions  of  fome  part  of  the  fyftem  commence  in  con- 
fequence  of  this  fenfation  conjointly  with  the  irritation  :  which 
motions  conftitute  inflammation,  If  the  fever  be  attended  with 
a  ftrong  pulfe,  as  in  pleurify,  or  rheumatifm,  it  is  termed  fyno- 
cha  fenfitiva  or  fenfitive  fever  with  ftrong  pulfe  ;  which  is  ufu- 
ally  termed  inflammatory  fever.  If  it  bs  attended  with  weak 

VOL,  I.  S  s  pulfe, 


'322 


DISEASES  SECT.  XXXI1L 


pulfe,  it  is  termed  typhus  fenfitivus,  or  fenfitive  fever  with  weak 
pulfe,  or  typhus  gravior,  or  putrid  malignant  fever. 

The  fynocha  fenfitiva,  or  fenfitive  fever  with  ftrong  pulfe,  is 
generally  attended  with  fome  topical  inflammation,  as  in  perip- 
neumony,  hepatitis,  and  is  accompanied  with  much  coagulable 
lymph,  or  fize ;  which  rifes  to  the  furface  of  the  blood,  when 
taken  into  a  bafm,  as  it  cools  ;  and  which  is  believed  to  be  the 
mcreafed  mucous  fecretion  from  the  coars  of  the  arteries,  infpif- 
fated  by  a  greater  abforption  of  its  aqueous  and  faline  part,  and 
perhaps  changed  by  its  delay  in  the  circulation. 

The  typhus  fenfitivus,  or  fenfitive  fever  with  weak  pulfe,  is 
frequently  attended  with  delirium,  which  is  caufed  by  the  de- 
ficiency of  the  quantity  of  fenforial  power,  and  with  variety  of 
cutaneous  eruptions. 

Inflammation  is  caufed  by  the  pains  occafioned  by  excefs  of 
action,  and  not  by  thofe  pains  which  are  occafioned  by  defect:  of 
action.  Thefe  morbid  actions,  which  are  thus  produced  by  two 
fenforial  powers,  viz.  by  irritation  and  fenfation,  fecrece  new 
living  fibres,  which  elongate  the  old  veifels,  or  form  new  ones, 
and  at  the  fame  time  much  heat  is  evolved  from  thefe  combina- 
tions. By  the  rupture  of  thefe  veflels,  or  by  a  new  conftruction 
of  their  apertures,  purulent  matters  are  fecrered  of  various  kinds  ; 
which  are  infectious  the  firft  time  they  are  applied  to  the  fkin 
beneath  the  cuticle,  or  fwallowed  with  the  faliva  into  the  ftom- 
ach. This  contagion  acts  not  by  its  being  abforbed  into  the 
circulation,  but  by  the  fympathies,  or  aflbciated  aclions,  between 
the  part  firft  ftimulated  by  the  contagious  matter  and  the  other 
parts  of  the  fyftem.  Thus  in  the  natural  imall-pox  the  conta- 
gion is  f wallowed  with  the  faliva,  and  by  its  ftimulus  inflames  the 
ftomach  ;  this  variolous  inflammation  of  the  ftomach  increafes 
every  day,  like  the  circle  round  the  puncture  of  an  inoculated 
arm,  till  it  becomes  great  enough  to  diforder  the  circles  of  irri- 
tative and  fenfitive  motions,  and  thus  produces  fever-fits,  with 
{icknefs  and  vomiting.  Laftly,  after  the  cold  paroxyfm,  or  fit 
of  torpor,  of  the  ftomach  has  increafed  for  two  or  three  fuccef- 
five  days,  an  inflammation  of  the  fkin  commences  in  points  ; 
which  generally  firft  appear  upon  the  face,  as  the  aflbciated  ac- 
tions between  the  fkin  of  the  face  and  that  of  the  ftomach  have 
been  more  frequently  exerted  together  than  thofe  of  any  other 
parts  of  the  external  furface. 

Contagious  matters,  as  thofe  of  the  meafles  and  fmall-pox,  do 
not  act  upon  the  fyftem  at  the  fame  time  ;  but  the  progrefs  of 
that  which  was  laft  received  is  delayed,  till  the  action  of  the 
former  infeftion  ceafes.  All  kinds  of  matter,  even  that  from 
common  ulcers,  are  probably  contagious  the  firft  time  they  are  in- 
fer ted 


SECT.  XXXIII.  4.  i.          OF  SENSATION.  323 

ferted  beneath  the  cuticle  or  fwallowed  into  the  ftomach  ;  that 
is,  as  they  were  formed  by  certain  morbid  adlions  of  the  ex- 
tremities of  the  vefiels,  they  have  the  power  to  excite  fimilar 
morbid  aftions  in  the  extremities  of  other  veffels,  to  which  they 
are  applied  ;  and  thefe  by  fympathy,  or  aflbciations  of  morion, 
excite  fimilar  morbid  actions  in  diftant  parts  of  the  fyftem,  with- 
out entering  the  circulation  ;  and  hence  the  blood  of  a  patient  in 
the  fmall-pox  will  not  give  that  difeafe  by  inoculation  to  others. 
When  the  new  fibres  or  veflels  become  again  abforbed  into 
the  circularion,  the  inflammation  ceafes  ;  which  is  promoted, 
after  fufficient  evacuation,  by  external  (limulants  and  bandages  : 
but  where  the  aft  ion  of  the  veflels  is  very  great,  a  mortification 
of  the  part  is  liable  to  enfue,  owing  to  the  exhauftion  of  fenfori- 
al  power  ;  which  however  occurs  in  weak  people  without  much 
pain,  and  without  very  violent  previous  inflammation  ;  and,  like 
partial  paralyfis,  may  be  efteemed  one  mode  of  natural  death 
of  old  people,  a  part  dying  before  the  whole. 


SECT, 


324  DISEASES         SECT.  XXXIV.   i.  i. 


SECT.       XXXIV. 

DISEASES    OF     VOLITION. 

I.  I.   Volition  defined.      Motions  termed  involuntary  are  canfed  by 
volition.     Deftres    cppofed  to  each  ether.      Deliberation,     sifs  be- 
tween two  hay- cocks.       Saliva  Jwaliowed  againjl    one's  defire. 
Voluntary  motions  difllnguifhed from  thcfe  officiated  withferfitive 
motions.      2.   Pains  from  excefsy  and  from  defecJ  oj  motion.      No 
pain  is  felt  during  vehement  voluntary  exertion  ;  (is  in  cold  fits  of 
ague^  labour-pains,  Jlrangury,  tenefmus^  vomiting,    refllejjiiefs  in 
fevers^  convulfion  of  a  wounded  mujcle.      3.    Of  holding  the  breath 
and  f creaming  in  pain  ;  why  Jwine  and  dogs  cry  out  in  pain ,  and 
notjheep  and  horfes.      Of  grinning  and  biting  in  pain  ;  why  mad 
animals  bite  others.      4.   Epileptic  convulfions   explained  >  why  the 
Jits  begin  with  quivering  of  the  under  jaw >  biting  the  tongue^  and 
fetting  the  teeth  ;   why  the  convulfive  motions  are  alternately  re/ax- 
ed.    "The  phanometwn  of  laughter  explained  >      Why  children  can- 
not tickle   themf elves.      How   feme  have   died  from  immoderate 
laughter.      5.   Of  cataleptic  fpafms^  of  the  locked  jaw 3  of  painful 
cramps.     6.   Syncope   explained.     Why  no    external  objects  are 
perceived  in  fynccpe.      7.    Of  palfy  and  apoplexy  from  violent  exer- 
tions.     Cafe  of  Mrs.  Scot-      From  dancing^  fcating,  fwimming. 
Cafe  of  Mr.  Nairne.      Why  palfies   are  not  always  immediately 
preceded    by  violent  exertions*      Palfy    and  epilepfy  from  di/eafed 
livers.      Why  the  right  arm  more  frequently  paralytic  than  the 
left.     How  paralytic  limbs  regain  their  motions.     II.   Difea/es  of 
the  fenfuai  motions  from  excefs  or  defeft  of    voluntary  exertion. 
I.   Aladnefs.      2.  Diftinguijhed  from  delirium •.      3.    Why  man- 
kind  more  liable  to  infanity    than  brutes.      Sufpicion       Want    of 
Jhame^  and  of  clean  linefs.    5.  They  bear  co/dy  hunger ,  and  fatigue. 
Charles  XII.  of  Sweden.      6.   Pleafurable  delirium,  and  infinity. 
Child  riding  on  a  flick.      Pains  of  martyrdom  not  felt.      7.  Drop- 
fy.      8.   Inflammation  cured  by   infanity.     III.    I.   Pain  relieved 
by  reverie.     Reverie  is  an  exertion  of  voluntary  andfenfttive  mo- 
tions.     2.  Cafe  of  reverie.      3.   Ladyfuppojedto  have  two  fouls. 
4.   Methods  of  relieving  pain. 

I.  i.  BEFORE  we  commence  this  Seflion  on  Difeafed  Vol- 
untary Motions,  it  may  be  neceflary  to  premife,  that  the  word 
volition  is  not  ufed  in  this  work  exactly  in  its  common  accepta- 
tion. Volition  is  faid  in  Section  V.  to  bear  the  fame  analogy  to 
defire  and  averfion,  which  fenfation  does  to  pleafure  and  pain. 
And  hence  that,  when  defire  or  averfion  produces  any  action  of 

the 


SECT.  XXXIV.  i.  i.      OF  VOLITION.  325 

the  mufcular  fibres,  or  of  the  organs  of  fenfe,  it  is  termed  voli- 
tion j  and  the  ad  ions  produced  in  confequence  are  termed  vol- 
untary a£tions>  Whence  it  appears,  that  motions  of  our  muf- 
cles  or  ideas  may  be  produced  in  confequence  of  defire  or  aver- 
fion without  our  having  the  power  to  prevent  them,  and  yet  thefe 
motions  may  be  termed  voluntary,  according  to  our  definition  of 
the  word  ;  though  in  common  language  they  would  be  called 
involuntary. 

The  objects  of  defire  andaverfion  are  generally  at  a  diftance, 
whereas  thofeof  pleafure  and  pain  are  immediately  acting  upon 
our  organs.  Hence,  before  defire  or  averfion  is  exerted,  fo  as 
to  caufe  any  actions,  there  is  generally  time  for  deliberation  ; 
which  confifts  in  difcoveriqg  the  means  to  obtain  the  object  of 
defire,  or  to  avoid  the  object  of  averfion  j  or  in  examining  the 
good  or  bad  confequences,  which  may  refult  from  them.  la 
this  cafe  it  is  evident,  that  we  have  a  power  to  delay  the  pro- 
pofed  action,  or  to  perform  it  ;  and  this  power  of  choofing, 
whether  we  {hall  act  or  not,  is  in  common  language  exprefied 
by  the  word  volition,  or  will.  Whereas  in  this  work  the  word 
volition  means  {imply  the  active  (late  of  the  fenforial  faculty  in 
producing  motion  in  confequence  of  defire  or  averfion  :  whether 
we  have  the  power  of  retraining  that  action,  or  not ;  that  is, 
whether  we  exert  any  adtions  in  confequence  of  oppofite  defires 
or  averfions  or  not. 

For  if  the  objects  of  defire  or  averfion  are  prefent,  there  is  no 
necenity  to  investigate  and  compare  the  means  of  obtaining  them, 
nor  do  we  always  deliberate  about  their  confequences  ;  that  is,, 
no  deliberation  necefiarily  intervenes,  and  in  confequence  the 
power  of  choofing  to  act  or  not  is  not  exerted.  It  is  probable* 
that  this  two-fold  ufe  of  the  word  volition  in  all  languages  has 
confounded  the  metaphyficians,  who  have  difputed  about  free 
will  and  neceflity.  Whereas  from  the  above  analyfis  it  would 
appear,  that  during  our  fleep,  we  ufe  no  voluntary  exertions  at 
all  ;  and  in  our  waking  hours,  that  they  are  the  confequence  of 
defire  or  averfion. 

To  will  is  to  act  in  confequence  of  defire  ;  but  to  defire 
means  to  defire  fomething,  even  if  that  fomethingbe  only  to  be- 
come free  from  the  pain,  which  caufes  the  defire  ;  for  to  defire 
nothing  is  not  to  defire  ;  the  word  defire,  therefore,  includes 
both  the  action  and  the  objed  or  motive ;  for  the  object  and 
motive  of  defire  are  the  fame  thing.  Hence  to  deiire  without  an 
object,  that  is,  without  a  motive,  is  a  folecifm  in  language.  As. 
if  one  fhould  aik,  if  you  could  eat  without  food,  or  breathe 
without  air. 

From  this  account  of  volition  it  appears,  that  coavulfions  o€ 

the 


326  DISEASES          SECT.  XXXIV.  i.  i, 

the  mufcles,  as  in  epileptic  fits,  may  in  the  common  fenfe  of  that 
word  be  termed  involuntary  •,  becaufe  no  deliberation  is  interpo- 
fed  between  the  defire  or  averfion  and  the  confequent  aclion  j 
but  in  the  fenfe  of  the  word,  as  above  defined,  they  belong  to 
the  clafs  of  voluntary  motions,  as  delivered  in  VoL  I  Clafs  III. 
If  this  ufe  of  the  word  be  difcordant  to  the  ear  of  the  reader, 
the  term  morbid  voluntary  motions,  or  motions  in  confequencc 
of  averfion,  may  be  fubflituted  in  its  (lead. 

If  a  perfon  has  a  defire  to  be  cured  of  the  ague,  and  has  at  the 
fame  time  an  averfion  (or  contrary  defire  )to  fwallowing  an  ounce 
of  Peruvian  bark  ;  he  balances  defire  againft  defire,  or  averfion 
againft  averfion  ;  and  thus  he  acquires  the  power  of  choofing, 
which  is  the  common  acceptation  of  the  word  'willing.  But  in 
the  cold  fit  of  ague,  after  having  difcovered  that  the  a£l  of 
fhuddering,  or  exerting  the  fubcutaneous  mufcles,  relieves  the 
pain  of  cold  ;  he  immediately  exerts  this  aft  of  volition,  and 
ihudders,  as  foon  as  the  pain  and  confequent  averfion  return, 
without  any  deliberation  intervening  ;  yet  is  this  a£l,  as  well  as 
that  of  fwallowing  an  ounce  of  the  bark,  caufed  by  volition  ;  and 
that  even  though  he  endeavours  in  vain  to  prevent  it  by  a  weak- 
er contrary  volition.  This  recals  to  our  minds  the  (lory  of  the 
hungry  afs  between  two  hay-flacks,  where  the  two  defires  are 
fuppofed  fo  exactly  to  counteract  each  other,  that  he  goes  to 
neither  of  the  flacks,  but  perifhes  by  want.  Now  as  two  equal 
and  oppofite  defires  are  thus  fuppofed  to  balance  each  other, 
and  prevent  all  adtion,  it  follows,  that  if  one  of  thefe  hay-flacks 
was  fuddenly  removed,  the  afs  would  irrefiftibly  be  hurried  to 
the  other,  which  in  the  common  ufe  of  the  word  might  be  call- 
ed an  involuntary  aft  ;  but  which,  in  our  acceptation  of  it, 
would  be  clafTed  amongft  voluntary  aftions,  as  above  explained. 

Hence  to  deliberate  is  to  compare  oppofing  defires  or  aver- 
iions,  and  that  which  is  the  moft  interefling  at  length  prevails, 
and  produces  aclion.  Similar  to  this,  where  two  pains  oppofe 
each  other,  the  ftronger  or  more  interefling  one  produces  ac- 
tion j  as  in  pleurify  the  pain  from  fufFocation  would  produce 
expanfion  of  the  lungs,  but  the  pain  occafioned  by  extending 
the  inflamed  membrane,  which  lines  the  cheft,  oppofes  this  ex- 
panfion, and  one  or  the  other  alternately  prevails. 

When  any  one  moves  his  hand  quickly  near  another  performs 
eyes,  the  eye-lids  inflantly  clofe  ;  this  a£l  in  common  language 
is  termed  involuntary,  as  we  have  not  time  to  deliberate  or  to 
exert  any  contrary  defire  or  averfion,  but  in  this  work  it  would 
be  termed  a  voluntary  a£l,  becaufe  it  is  caufed  by  the  faculty  of 
volition,  and  after  a  few  trials  the  nictitation  can  be  prevented 
by  a  contrary  or  oppofing  volition. 

The 


SECT.  XXXIV.  1. 1.         OF  VOLITION.  327 

The  power  of  oppofing  volitions  is  bed  exemplified  in  the 
flory  of  Mutius  Scsevola,  who  is  faid  to  have  thruft  his  hand 
into  the  fire  before  Porcenna,  and  to  have  fuffered  it  to  be  con- 
fumed  for  having  failed  him  in  his  attempt  on  the  life  of  that 
general  Here  the  averfion  for  the  lofs  of  fame,  or  the  unfatis- 
fied  rlefire  to  ferve  his  couutry,  the  too  prevalent  enthufiafms  at 
that  time,  were  more  powerful  than  the  defire  of  withdrawing 
his  hand,  which  mud  be  occasioned  by  the  pain  of  cornbuftion  ; 
of  thefe  oppofing  volitions 

Vincit  amor  patrige,  laudumque  imxnenfa  cupido. 

If  any  one  is  told  not  to  fwallow  his  faliva  for  a  minute,  he 
foon  fwallows  it  contrary  to  his  will,  in  the  common  fenfe  of  that 
word  ;  but  this  alfo  is  a  voluntary  a£tion,  as  it  is  performed  by 
the  faculty  of  volition,  and  is  thus  to  be  underftood.  When 
the  power  of  volition  is  exerted  on  any  of  our  fenfes,  they  be- 
come more  acute,  as  in  our  attempts  tq  hear  fmall  noifes  in  the 
night.  As  explained  in  Section  XIX.  6.  Hence  by  our  atten- 
tion to  the  fauces  from  our  defire  not  to  fwallow  our  faliva  ; 
the  fauces  become  more  fenfible  ;  and  the  (limulus  of  the  fali- 
va is  followed  by  greater  fenfation,  and  confequent  defire  of 
fwallowing  it.  So  that  the  defire  or  volition  in  confequence  of 
the  increased  fenfation  of  the  faliva  is  more  powerful,  than  the 
previous  defire  not  to  fwallow  it.  See  Vol.  I  Deglutitio  in- 
vita.  In  the  fame  manner  if  a  modeft  man  wiflies  not  to  want 
to  make  water,  when  he  is  confined  with  ladies  in  a  coach  or  an 
afTembly  room ;  that  very  acl:  of  volition  induces  the  circum- 
ftance,  which  he  wimes  to  avoid,  as  above  explained  ;  infomuch 
that  I  once  faw  a  partial  infanity,  which  might  be  called  a  vol- 
untary diabetes,  which  was  occafioned  by  the  fear  (and  confe- 
quent averfion)  of  not  being  able  to  make  water  at  all. 

It  is  further  neceflary  to  obferve  here,  to  prevent  any  confu- 
fion  of  voluntary,  with  fenfitive,  or  aflbciate  motions,  that  in  all 
the  inftances  of  violent  efforts  to  relieve  pain,  thofe  efforts  are 
at  firft  voluntary  exertions  ;  but  after  they  have  been  frequent- 
ly repeated  for  the  purpofe  of  relieving  certain  pains,  they  be- 
come aflbciated  with  thofe  pains,  and  ceafe  at  thofe  times  to  be 
fubfervient  to  the  will ;  as  in  coughing,  fneezing,  and  in  ftrangu- 
ry.  Of  thefe  motions  thofe  which  contribute  to  remove  or  dif- 
lodge  the  offending  caufe,  as  the  a£tions  of  the  abdominal  muf- 
cles  in  parturition  or  in  vomiting,  though  they  were  originally 
excited  by  volition,  are  in  this  work  termed  fenfitive  motions ; 
but  thofe  a 61  ions  of  the  mufcles  or  organs  of  fenfe,  which  do 
not  contribute  to  remove  the  offending  caufe,  as  in  general  con- 
vulfions  or  in  madnefs,  are  in  this  work  termed  voluntary  mo- 
tions, 


328  DISEASES  SECT.  XXXIV.  i  2. 

tions,  or  motions  in  confequence  of  avevfion,  though  in  common 
language  they  are  called  involuntary  ones.  Thofe  fenfitivc  un- 
reftrainable  actions,  which  contribute  to  remove  the  caufe  of 
pain  are  uniformly  and  invariably  exerted,  as  in  coughing  or 
freezing ;  but  thofe  motions  which  are  exerted  in  confequence 
of  averfion  without  contributing  to  remove  the  painful  caufe,  but 
only  to  prevent  the  fenfation  of  it,  as  in  epileptic  or  cataleptic 
fits,  are  not  uniformly  and  invariably  exerted,  but  change  from 
one  fet  of  mufcles  to  another,  as  will  be  further  explained  ; 
and  may  by  this  criterion  alfo  be  diftinguifhed  from  the  former. 

At  the  fame  time  thofe  motions,  which  are  excited  by  per- 
petual ftimuius,  or  by  affociation  with  each  other,  or  immedi- 
ately by  pleafurable  or  painful  fenfation,  may  properly  be  term- 
ed involuntary  motions,  as  thofe  of  the  heart  and  arteries  ;  as 
the  faculty  of  volition  feldom  affects  thofe,  except  when  it  exifts 
in  unnatural  quantity,  as  in  maniacal  people, 

2.  It  was  obferved  in  Section  XIV.  on  the  Production  of 
Ideas,  that  thofe  parts  of  the  fyftem,  which  are  ufually  termed 
the  organs  of  fenfe,  are  liable  to  be  excited  into  pain  by  the  ex- 
cefs of  the  ftimuius  of  thofe  objects,  which  are  by  nature  adapt- 
ed to  effect  them  ;  as  of  too  great  light,  found,  or  preffure.  But 
that  thefe  organs  receive  no  pain  from  the  defect  or  abfence  of 
thefe  ftimuli,  as  in  darknefs  or  filence.  But  that  our  other  or- 
gans of  perception,  which  have  generally  been  called  appetites, 
as  of  hunger,  third,  want  of  heat,xwant  of  frefh  air,  are  liable  to 
be  affected  with  pain  by  the  defect,  as  well  as  by  the  excefs  of 
their  appropriated  (Hmuli. 

This  excefs  or  defect  of  ftimuius  is  however  to  be  confidered 
only  as  the  remote  caufe  of  the  pain,  the  immediate  caufe  being 
the  excels  or  defect  of  the  natural  action  of  the  affected  part, 
according  to  Sect.  IV.  5.  Hence  ail  the  pains  of  the  body  may 
be  divided  into  thofe  from  excels  of  motion,  and  thofe  from  de- 
fect of  motion,  which  diftinction  is  of  great  importance  in  the 
knowledge  and  the  cure  of  many  difeafes.  For  as  the  pains 
from  the  excefs  of  motion  either  gradually  fubfide,  or  are  in 
general  fucceeded  by  inflammation  ;  fo  thofe  from  defect  of 
motion  either  gradually  fubfide,  or  are  in  general  fucceeded  by 
convulfion,  or  madnefs.  Thefe  pains  are  eafily  diftinguifhable 
from  each  other  by  this  circumftance,  that  the  former  are  attend- 
ed with  heat  of  the  pained  part,  or  of  the  whole  body  ;  where- 
as the  latter  exid  without  increafe  of  heat  in  the  pained  part, 
and  are  generally  attended  with  coldnefs  of  the  extremities  of 
the  body  •,  which  is  the  true  criterion  of  what  have  been  called 
nervous  pains. 

Tims  when  any  acrid  material,  as  fnuff  or  lime  falls  into  the 

eye, 


SECT.  XXXIV.  i..a.      OF  VOLITION.  32p 

eye,  pain  and  inflammation  and  heat  are  produced  from  the  ex- 
cefs  of  ftimulus ;  but  violent  hunger,  hemicrania,  or  the  clavus 
hyftericus,  are  attended  with  coldnefs  of  the  extremities,  and  de- 
fe&  of  circulation.  When  we  are  expofed  to  great  cold,  the 
pain  we  experience  from  the  deficiency  of  heat  is  attended  with 
a  quiefcence  of  the  motions  of  the  vafcular  fyftem  ;  fo  that  no 
inflammation  is  produced,  but  a  great  defire  of  heat,  and  a  trem- 
ulous motion  of  the  fubcutaneous  mufcles,  which  is  properly  a 
convulfion  in  confequence  of  this  pain  from  defect  of  the  (timu- 
lus  of  heat. 

It  was  before  mentioned,  that  as  fenfation  confifts  in  certain 
movements  of  the  fenforium,  beginning  at  fome  of  the  extremi- 
ties of  it,  and  propagated  to  the  central  parts  of  it  j  fo  volition 
confifts  of  certain  other  movements  of  the  fenforium,  commenc- 
ing in  the  central  parts  of  it,  and  propagated  to  fome  of  its  extrem- 
ities. This  idea  of  thefe  two  great  powers  of  motion  in  the  ani- 
mal machine  is  confirmed  from  observing,  that  they  never  exiit 
in  a  great  degree  or  univerfally  at  the  fame  time  ;  for  while  we 
firongly  exert  our  voluntary  motions,  we  ceafe  to  feel  the  pains 
or  uneafmefles,  which  occafioned  us  to  exert  them. 

Hence  during  the  time  of  fighting  with  fifts  or  fwords  no 
pain  is  felt  by  the  combatants,  till  they  ceafe  to  exert  themfelves. 
Thus  in  the  beginning  of  ague- fits  the  painful  fenfation  of  cold 
is  dimiuiihed,  while  the  patient  exerts  himfelf  in  the  (hivering 
and  gnafhing  of  his  teeth.  He  then  ceafes  to  exert  himfelf»  and 
the  pain  of  cold  returns ;  and  he  is  thus  perpetually  induced 
to  reiterate  thefe  exertions,  from  which  he  experiences  a  tem- 
porary relief.  The  fame  occurs  in  labour- pains,  the  exertion  of 
the  parturient  woman  relieves  the  violence  of  the  pains  for  a 
time,  which  recur  again  foon  after  fhe  has  ceafed  to  ufe  thofe 
exertions.  The  fame  is  true  in  many  other  painful  difeafes,  as 
in  the  ttrangury,  tenefmus,  and  the  efforts  of  vomiting  j  all 
thefe  difagreeable  fenfations  are  diminifhed  or  removed  for  a 
time  by  the  various  exertions  they  occafion,  and  recur  alter- 
nately with  thofe  exertions 

The  re  (lie  (The  fs  in  fome  fevers  is  an  almoft  perpetual  exertion 
of  this  kind,  excited  to  relieve  fome  difagreeable  fenfations  ;  the 
reciprocal  oppofite  exertions  of  a  wounded  worm,  the  alternate 
emproithotonos  and  opifthotonos  of  fome  fpafmodic  difeafes,  and 
the  intervals  of  all  convulfions,  from  whatever  caufe,  feem  to  be 
owing  to  this  circumftanceof  the  laws  of  animation  ;  that  great 
or  univerfal  exertion  cannot  exift  at  the  fame  time  with  great 
or  univerfal  fenfation,  though  they  can  exifl  reciprocally  ;  which 
is  probably  refolvable  into  the  more  general  law,  that  the  whole 
fenforial  power  being  expended  in  one  mode  of  exertion,  there 

VOL.  I.  T  T  is 


33o  DISEASES  SECT.  XXXIV  .1.3. 

is  none  to  fpare  for  any  other.     Whence  fyncope,  or  temporary 
apoplexy,  iucceeds  to  epileptic  convulfjons. 

3.  Hence  when  any  violent  pain  afflidls  us,  of  which  we  can 
neither  avoid  nor  remove  the  caufe.  we  foon  learn  to  endeavour 
to  alleviate  it,  by  exerting  fome  violent  voluntary  effort,  as  men- 
tioned above  ;  and  are  naturally  induced  to  ufe  thofe  mufcles 
for  this  purpofe,  which  have  been  in  the  early  periods  of  our 
lives  mod  frequently  or  moft  powerfully  exerted. 

Now  the  firft  mufcles,  which  infants  ufe  moft  frequently,  are 
thofe  of  refpiration  ;  and  on  this  account  we  gain  a  habit  of 
holding  our  breath,  at  the  fame  time  that  we  uie  great  efforts 
to  exclude  it,  for  this  purpofe  of  alleviating  unavoidable  pain ; 
or  we  prefs  out  our  breath  through  a  fmall  aperture  of  the 
larynx,  and  fcream  violently,  when  the  pain  is  greater  than  i& 
relievable  by  the  former  mode  of  exertion.  Thus  children 
fcream  to  relieve  any  pain  either  of  body  or  mind,  as  from 
anger,  or  fear  of  being  beaten. 

Hence  it  is  curious  to  obferve,  that  thofe  animals,  who  have 
more  frequently  exerted  their  mufcles  of  refpiration  violently, 
as  in  talking,  barking  or  grunting,  as  children,  dogs,  hogs,  fcream 
much  more  when  they  are  in  pain,  than  thofe  other  animals, 
who  uie  little  or  no  language  in  their  common  modes  of  life  j 
as  horfes,  fheep,  and  cows. 

The  next  moft  frequent  or  moft  powerful  efforts,  which  in- 
fants are  firft  tempted  to  produce,  are  thofe  with  the  mu  cles  in 
biting  hard  fubftances  •,  indeed  the  exertion  of  thefe  mufcles  is 
very  powerful  in  common  maftication,  as  appears  from  the  pain 
we  receive,  if  a  bit  of  bone  is  unexpectedly  found  amongft  our 
fofter  food  ;  and  further  appears  from  their  afting  to  fo  great 
mechanical  difadvantage,  particularly  when  we  bite  with  the  in- 
cifores,  or  canine  teeth  ;  which  are  firft  formed,  and  thence  are 
firft  ufed  to  violent  exertion. 

Hence  when  a  perfon  is  in  great  pain,  the  caufe  of  which  he 
cannot  remove,  he  fets  his  teeth  firmly  together,  or  bites  fome 
fubftance  between  them  with  great  vehemence,  as  another 
mode  of  violent  exertion  to  produce  a  temporary  relief.  Thus 
we  have  a  proverb  where  no  help  can  be  had  in  pain,  "  to  grin 
and  abide  -,"  and  the  tortures  of  hell  are  faid  to  be  attended  with 
«  gnafhing  of  teeth," 

Hence  in  violent  fpafmodic  pains  I  have  feen  people  bite  not 
only  their  tongues,  but  their  arms  or  fingers,  or  thofe  of  the  at- 
tendants, or  any  object  which  was  near  them  ;  and  alfo  (hike, 
pinch,  or  tear,  others  or  themfelves,  particularly  the  part  of 
their  own  body,  which  is  painful  at  the  time.  Soldiers,  who 
die  of  painful  wounds  in  battle,  are  faid  in  Homer  to  bite  the 

ground. 


•SECT.  XXXIV.  i.  4-        OF  VOLITION.  33  x 

ground.  Thus  alfc  in  the  bellon,  or  colica  faturnina,  the  pa- 
tients are  faid  to  bite  their  own  fle(h,and  dogs  in  this  difeafe  to 
bite  up  the  ground  they  lie  upon.  It  is  probable  that  the  great 
endeavours  to  bite  in  mad  dogs,  and  the  violence  of  other  mad 
animals,  are  owing  to  the  fame  caufe. 

4.  If  the  efforts  of  our  voluntary  motions  are  exerted  with 
ftill  greater  energy  for  the  relief  of  fofne  difagreeable  fenfation, 
convulfions  are  produced  ;  as  the  various  kinds  of  epilepfy,  and 
in  fome  hyfleric  paroxyfms.  In  all  thefe  difeafes  a  pain  or  difa- 
greeable fenfation  is  produced,  frequently  by  worms,  or  acidity 
in  the  bowels,  or  by  a  difeafed  nerve  in  the  fide,  or  head,  or  by 
the  pain  of  a  difeafed  liver. 

In  fome  conftitutions  a  more  intolerable  degree  of  pain  is 
produced  in  fome  part  at  a  diftance  from  the  caufe  by  fenfitive 
affociation,  as  before  explained  ;  thefe  pains  in  fuch  conititutions 
arife  to  fo  great  a  degree,  that  I  verily  believe  no  artificial  tor- 
tures could  equal  fome,  which  I  have  witnefled  ;  and  am  confi- 
dent life  would  not  have  long  been  preferved,  unlefs  they  had 
been  foon  diminifhed  or  removed  by  the  univerfal  convulfion  of 
the  voluntary  motions,  or  by  temporary  madnefs. 

In  fome  of  the  unfortunate  patients  I  have  obferved,  the  pain 
has  rifen  to  an  inexpreiTible  degree,  as  above  defcribed,  before 
the  convulfions  have  fupervened  ;  and  which  were  preceded  by 
fcreaming,  and  grinning  ;  in  others,  as  in  the  common  epilepfy, 
the  convulfion  has  immediately  fucceeded  the  commencement  of 
the  difagreeable  fenfations  ;  and  as  a  ftupor  frequently  fucceeds 
the  convulfions,  they  only  feemed  to  remember  that  a  pain  at  the 
ftomach  preceded  the  fit,  or  fome  other  uneafy  feel ;  or  more 
frequently  retained  no  memory  at  all  of  the  immediate  caufe  of 
the  paroxyfm.  But  even  in  this  kind  of  epilepfy,  where  the  pa- 
tient does  not  recolleft  any  preceding  pain,  the  paroxyfms  gen- 
erally are  preceded  by  a  quivering  motion  of  the  under  jaw, 
with  a  biting  of  the  tongue  ;  the  teeth  afterwards  become  preff- 
ed  together  with  vehemence,  and  the  eyes  are  then  convulfed, 
before  the  commencement  of  the  univerfal  convulfion  ;  which 
are  all  efforts  to  relieve  pain. 

Thereafon  why  thefe  convulfive motions  are  alternately  exerted 
and  remitted  was  mentioned  above,  and  in  Se£t.  XII.  i.  3. 
*when  the  exertions  are  fuch  as  give  a  temporary  relief  to  the 
pain,  which  excites  them,  they  ceafe  for  a  time,  till  the  pain  is 
again  perceived  ;  and  then  new  exertions  are  produced  for  its 
relief.  We  fee  daily  examples  of  this  in  the  loud  reiterated 
laughter  of  fome  people  ;  the  pleafurable  fenfation,  which  ex- 
cites this  laughter,  arifes  for  a  time  fo  high  as  to  change  its  name 
and  become  painful  :  the  convulfirs  motions  of  the  refpiratory 

mufcles 


332  DISEASES        SECT.  XXXIV.  i.  4, 

mufcles  relieve  the  pain  for  a  time  ;  we  are,  however,  unwil- 
ling to  lofe  the  pleafure,  and  prefently  put  u  (top  to  this  exer- 
tion, and  immediately  the  pleafure  recurs,  and  again  as  inftantly 
rifes  into  pain-  All  of  us  have  felt  the  pain  of  immoderate 
laughter  ;  children  have  been  tickled  into  convulfions  of  the 
whole  body  ;  and  others  have  died  in  the  acl:  of  laughing  ; 
probably  from  a  paralyfis  fucceeding  the  long  continued  actions 
of  the  mufcles  of  refpiration. 

Hence  we  learn  the  reafon,  why  children,  who  are  fo  eafily 
excited  to  Jaugh  by  the  tickling  of  other  people's  fingers,  cannot 
tickle  themfelves  into  laughter  The  exertion  of  their  hands  in 
the  endeavour  to  tickle  themfelves  prevents  the  neceffity  of  any 
exenion  of  the  refpiratory  mufcles  to  relieve  the  excefs  of  pleaf- 
urable  affedion.  See  Scflt  XVII.  3.5. 

Chryfippus  is  recorded  to  have  died  laughing,  when  an  afs 
was  invited  to  fup  with  him.  The  fame  is  related  of  one  of  the 
popes,  who,  when  he  was  ill,  faw  a  tame  monkey  at  his  bed-fide 
put  on  the  holy  tiara.  Hall.  Phyf.  T  III.  p.  306. 

There  are  inftances  of  epilepfy  being  produced  by  laughing 
recorded  by  VanSwieten,  T.  III.  402  and  308.  And  it  is  well 
known,  that  many  people  have  died  inftantaneoufly  from  the 
painful  excefs  of  joy,  which  probably  might  have  been  prevent- 
ed by  the  exertions  of  laughter. 

Every  combination  of  ideas,  which  we  attend  to,  occafions 
pain  or  pleafure  ;  thofe  which  occafion  pleafure,  furnifh  either 
focial  or  felfim  pleafure,  either  malicious  or  friendly,  or  lafcivi- 
ous,  or  fublime  pleafure  ;  that  is,  they  give  us  pleafure  mixed 
with  other  emotions,  or  they  give  us  unmixed  pleafure,  without 
occafioning  any  other  emotions  or  exertions  at  the  fame  time. 
This  unmixed  pleafure,  if  it  be  great,  becomes  painful,  like  all 
other  animal  motions  from  ftimuli  of  every  kind  ;  and  if  no 
other  exertions  are  occafioned  at  the  fame  time,  we  ufe  the  ex- 
ertion of  laughter  to  relieve  this  pain.  Hence  laughter  is  occa- 
fioned by  fuch  wit  as  excites  (imply  pleafure  without  any  other 
emotion,  fuch  as  pity,  love,  reverence.  For  fublime  ideas  are 
mixed  with  admiration,  beautiful  ones  with  love,  new  ones  with 
furprife  ;  and  thefe  exertions  of  our  ideas  prevent  the  action  of 
laughter  from  being  neceflary  to  relieve  the  painful  pleafure 
above  defcribed.  Whence  laughable  wit  confifts  of  frivolous 
ideas,  without  connexions  of  any  confequence,  fuch  as  puns  on 
words,  or  on  phrafes,  incongruous  junctions  of  ideas  ;  on  which 
account  laughter  is  fo  frequent  in  children. 

Unmixed  pleafure  lefs  than  that,  which  caufes  laughter,  caufes 
fleep,  as  in  finging  children  to  fleep,  or  in  flight  intoxication  from 
wine*  or  food.  See  Se£t.  XVIII.  1 2. 


SECT.  XXXIV.  i.  5.        OF  VOLITION.  333 

5,  If  the  pains,  or  difagreeable  fenfations,  above  defcribeddo 
not  obtain  a  temporary  relief  from  thefe  convulfive  exertions  of 
the  mufcles,  thole  convulfive  exertions  continue  without  remif- 
fion,  and  one  kind  of  catalepfy  is  produced.     Thus  when  a  nerve 
or  tendon  produces  great  pain  by  its  being  inflamed  or  wounded, 
the  patient  fets  his  teeth  firmly  together,  and  grins  violently,  to 
diminifh  the  pain  ;  and  if  the  pain  is  not  relieved  by  this  exer- 
tion, no  relaxation  of  the    maxillary  mufcles  takes  place,  as  in 
the  convuifions  above  defcribed,  but  the  jaws  remain  firmly 
fixed  together.     This  locked  jaw  is  the  moft  frequent  inftanct 
of  cataleptic  fpafm,  becaufe  we  are  more  inclined  to  exert  the 
mufcles  fubfervient  to  maftication  from  their  early  obedience  to 
violent  efforts  of  volition. 

But  in  the  cafe  related  in  Se£h  XIX.  on  Reverie,  the  catalep- 
tic lady  had  pain  in  her  upper  teeth  •,  and  pre fling  one  of  her 
hands  vehemently  againfl  her  cheek  bone  to  diminifh  this  pain5 
it  remained  in  that  attitude  for  about  half  an  hour  twice  a  day, 
till  the  painful  paroxyfm  was  over. 

I  have  this  very  day  feen  a  young  lady  in  this  difeafe,  (with 
which  (he  has  frequently  been  .jffllrled ;)  (he  began  to-day  with 
violent  pain  (hooting  from  one  fide  of  the  forehead  to  the  occi- 
put, and  after  various  druggies  lay  on  the  bed  with  her  fingers 
and  wrifts  bent  and  ftifffor  about  two  hours;  in  other  refpccls 
{he  Teemed  in  a  fyncope  with  a  natural  pulfe.  She  then  had  in- 
tervals of  pain  and  of  fpafm,  and  took  three  grains  of  opium 
every  hoar  till  (he  had  taken  nine  grains,  before  the  pains  and 
fpafm  ceafed. 

There  is,  however,  another  fpecies  of  fixed  fpafm,  which  dif- 
fers from  the  former,  as  the  pain  exifts  in  the  contracted  mufcle, 
and  would  feem  rather  to  be  the  confequence  than  the  caufe  of 
the  contraction,  as  in  the  cramp  in  the  calf  of  the  leg,  and  ia 
many  other  parts  of  the  body. 

In  thefe  fpafms  it  (hould  feem,  that  the  mufcle  itfelf  is  firft 
thrown  into  contraction  by  fome  difagreeable  fenfation,  as  of 
cold  ;  and  that  then  the  violent  pain  is  produced  by  the  great 
contraction  of  the  mufcular  fibres  extending  its  own  tendons, 
•which  are  faid  to  be  fenfible  to  extenfion  only  j  and  is  further 
explained  in  Seel.  XVIII.  15. 

6.  Many  inftances  have  been  given  in  this  work,  where  after 
violent  motions  excited  by  irritation,  the  organ  has  become  qui~ 
efcent  to  Icfs,  and  even  to  the  great  irritation,  whidi  induced  it 
into  violent  motion  ;  as  after  looking  long   at  the  fun  or  any 
bright  colour,  they  ceafe  to  be  feen ;  and  after  removing  from 
bright  day- light  into  a  gloomy  room,  the  eye  cannot  at  firft  per- 
ceive the  objects,  which  ftirnulate  it  lefs.     Similar  to  this  is  the 

fyncope, 


334  DISEASES         SECT.  XXXIV.  i.  7. 

fyncope,  which  fucceeds  after  the  violent  exertions  of  our  vol- 
untary motions,  as  after  epileptic  fits,  for  the  power  of  volition 
acts  in  this  cafe  as  the  ftimulus  in  the  other.  This  fyncope  is  a 
temporary  palfy,  or  apoplexy,  which  ceafes  after  a  time,  the  muf- 
cles  recovering  their  power  of  being  excited  into  aclion  by  the 
efforts  of  volition  ;  as  the  eye  in  the  circumftance  above  men- 
tioned recovers  in  ^  little  time  its  power  of  feeing  objects  in  a 
gloomy  room  ;  which  were  invifible  immediately  after  coming 
out  of  a  ftronger  light.  This  is  owing  to  an  accumulation  of 
fenforial  power  during  the  inaction  of  thofe  fibres,  which  were 
before  accuftomed  to  perpetual  exertions,  as  explained  in  Seel:. 
XII.  7.  i.  A  flighter  degree  of  this  difeafe  is  experienced  by~ 
every  one  after  great  fatigue,  when  the  mufcles  gain  fuch  inabili- 
ty to  further  action,  that  we  are  obliged  to  reft  them  for  a  while, 
or  to  fummon  a  greater  power  of  volition  to  continue  their 
motions. 

In  all  the  fyncopes,  which  I  have  feen  induced  after  convul- 
five  fits,  the  pulfe  has  continued  natural,  though  the  organs  of 
fenfe,  as  well  as  the  locomotive  mufcles,  have  ceafed  to  perform 
their  functions ;  for  it  is  neceflary  for  the  perception  of  objects, 
that  the  external  organs  of  fenfe  ihould  be  properly  excited  by 
the  voluntary  power,  as  the  eye-lids  muft  be  open,  and  perhaps 
the  mufcles  of  the  eye  put  into  action  to  diftend,  and  thence 
give  greater  pellucidity  to  the  cornea,  which  in  fyncope,  as  in 
death,  appears  flat  and  lefs  tranfparent.  The  tympanum  of  the 
ear  alfo  feems  to  require  a  voluntary  exertion  of  its  mufcles,  to 
gain  its  due  tenfion,  and  it  is  probable  the  other  external  organs 
of  fenfe  require  a  fimilar  voluntary  exertion  to  adapt  them  to 
the  diflinct  perception  of  objects.  Hence  in  fyncope  as  in  fleep, 
as  the  power  of  volition  is  fufpended,  no  external  objects  are 
perceived.  See  Sect.  XVIII  5.  During  the  time  which  the 
patient  lies  in  a  fainting  fit,  the  fpirit  of  animation  becomes  ac- 
cumulated :  and  hence  the  mufcles  in  a  while  become  irritable 
by  their  ufual  ilimulation,  and  the  fainting  fit  ceafes.  See  Sect. 
XII.  7.  i. 

7.  If  the  exertion  of  the  voluntary  motions  has  been  ftill  more 
energetic,  the  quiefcence,  which  fucceeds,  is  fo  complete,  that 
they  cannot  again  be  excited  into  action  by  the  efforts  of  the 
will.  In  this  manner  the  palfy,  and  apoplexy  (which  is  an  uni- 
verfal  paify)  are  frequently  produced  after  convulfions,  or  other 
violent  exertions  5  of  this  I  {hall  add  a  few  inftances. 

Platnerus  mentions  fome,  who  have  died  apoplectic  from  vio- 
lent exertions  in    dancing  ;  and  Dr.  Mead,  in  his  eflay  on  Poi- 
fons,  records   a  patient  in  the   hydrophobia,  who  at  one  effort 
broke  the  cords   which  bound  him,  and  at  the  fame  inftarit  ex- 
pired o 


SECT.  XXXIV.  i.  7.        OF  VOLITION.  335 

pired.  And  it  is  probable,  that  thofe,  who  have  expired  from 
immoderate  laughter,  have  died  from  this  paralyfis  confequent 
to  violent  exertion.  Mrs.  Scott  of  Stafford  was  walking  in  her 
garden  in  perfect  health  with  her  neighbour  Mrs. •,  the  lat- 
ter accidentally  fell  into  a  muddy  rivuletr  and  tried  in  vain  to 
difengage  herlelf  by  the  afiiftance  of  Mrs.  Scott's  hand.  Mrs. 
Scott  exerted  her  utmoft  power  for  many  minutes,  firfl  to  aflift 
her  friend,  and  next  to  prevent  herfelf  from  being  pulled  into 
the  morafs,  as  her  diftreffed  companion  would  not  difengage 
her  hand.  After  other  afiiftance  was  procured  by  their  united 
fcreams,  Mrs.  Scott  walked  to  a  chair  about  twenty  yards  from 
the  brook,  and  was  feized  with  an  apoplectic  ftroke  :  which 
continued  many  days,  and  terminated  in  a  total  lofs  of  her  right 
arm,  and  her  fpeech  •,  neither  of  which  (he  ever  after  perfectly 
recovered. 

It  is  faid,  that  many  people  in  Holland  have  died  after  fkating 
too  long  or  too  violently  on  their  frozen  canals  ;  it  is  probable 
the  death  of  thefe,  and  of  others,  who  have  died  fuddenly  in 
fwimming,  has  been  owing  to  this  great  quiefcence  or  paralyfis  ; 
which  has  fucceeded  very  violent  exertions,  added  to  the  con- 
comitant cold,  which  has  had  greater  effect  after  the  fufferers 
had  been  heated  and  exhaufted  by  previous  exercile. 

I  remember  a  young  man  of  the  name  of  Nairne  at  Cambridge, 
who  walking  on  the  edge  of  a  barge  fell  into  the  river.  His 
coufm  and  fellow-ftudent  of  the  fame  name,  knowing  the  other 
could  not  fwim,  plunged  into  the  water  after  him,  caught  him 
by  his  clothes,  and  approaching  the  bank  by  a  vehement  exertion 
propelled  him  fafe  to  the  land,  but  that  initant,  feized,  as  was 
fuppofed,  by  the  cramp,  or  paralyfis,  funk  to  rife  no  more.  The 
reafon  why  the  cramp  of  the  mufcles,  which  compofe  the  calf 
of  the  leg,  is  fo  liable  to  affect  fwimmers,  is,  becaufe  thefe  muf- 
cles have  very  weak  antagonifts,  and  are  in  walking  generally 
elongated  again  after  their  contraction  by  the  weight  of  the  body 
on  the  ball  of  the  toe,  which  is  very  much  greater  than  the  re- 
fiftance  of  the  water  in  fwimming.  See  Section  XVIII.  15. 

It  does  not  follow  that  every  apoplectic  or  paralytic  attack  is 
immediately  preceded  by  vehement  exertion  ;  the  quiefence, 
which  fucceeds  exertion,  and  which  is  not  fo  great  as  to  be  term- 
ed paralyfis,  frequently  recurs  afterwards  at  certain  periods  ; 
and  by  other  caufes  of  quiefcence,  occurring  with  thofe  periods, 
as  was  explained  in  treating  of  the  paroxyfms  of  intermitting 
fevers  \  the  quiefcence  at  length  becomes  fo  great  as  to  be  in- 
capable of  again  being  removed  by  the  efforts  of  volition,  and 
complete  paralyfis  is  formed.  See  Section  XXXII.  3.  2. 

Many  of  the  paralytic  patients,  whorn  I  have  feen,  have  evi- 

dentlv 


DISEASES          SECT.  XXXIV.  2.  i, 

dently  had  difeafed  livers  from  the  too  frequent  potation  of 
fpirituous  liquors ;  fome  of  them  have  had  the  gutta  rofea  ort 
their  faces  and  breads  ;  which  has  in  fome  degree  receded  either 
fpontaneoufly,  or  by  the  ufe  of  external  remedies,  and  the  para- 
lytic ftroke  has  fucceeded  ;  and  as  in  feveral  perfons,  who  have 
drunk  much  vinous  fpirits,  I  haveobferved  epileptic  fits  to  com- 
mence at  about  forty  or  fifty  years  of  age,  without  any  heredita- 
ry taint,  from  the  flimulus,  as  I  believed,  of  a  difeafed  liver  ;  I 
was  induced  to  afcribe  many  paralytic  cafes  to  the  fame  fource  ; 
which  were  riot  evidently  the  effect  of  age,  or  of  unacquired  de- 
bility. And  the  account  given  before  of  dropfies,  which  very 
frequently  are  owing  to  a  paralyfis  of  the  abforbent  fyltem,  and 
are  generally  attendant  on  free  drinkers  of  fpirituous  liquors, 
confirmed  me  in  this  opinion. 

The  difagreeable  irritation  of  a  difeafed  liver  produces  exer- 
tions and  confequent  quiefcence ;  thefe  by  the  accidental  con- 
currence of  other  caufes  of  quiefcence,  as  cold,  folar  or  lunar 
periods,  inanition,  the  want  of  their  ufual  portion  of  fpirit  of 
wine,  at  length  produce  paralyfis. 

This  is  further  confirmed  by  obferving,  that  the  mufcles,  we 
mod  frequently,  or  mod  powerfully  exert,  are  mod  liable  to 
pally  ;  as  thofe  of  the  voice  and  of  articulation,  and  of  thofe 
paralytics  which  I  have  feen,  a  much  greater  proportion  have 
loll  the  ufe  of  their  right  arm  ;  which  is  fo  much  more  gener- 
ally exerted  than  the  left. 

I  cannot  difmifs  this  fubjeft  without  obferving,  that  after  a 
paralytic  ftroke,  if  the  vital  powers  are  not  much  injured,  the 
patient  has  all  the  movements  of  the  affe&ed  limb  to  learn  over 
again,  juft  as  in  early  infancy  ;  the  limb  is  firft  moved  by  the 
irritation  of  its  mufcles,  as  in  ftretching,  (of  which  a  cafe  was 
related  in  Section  VII.  i.  3.)  or  by  the  electric  concuflion ; 
afterwards  it  becomes  obedient  to  fenfation,  as  in  violent  danger 
or  fear  ;  and  laftly,  the  mufcles  become  again  affociated  with 
volition,  and  gradually  acquire  their  ufual  habits  of  acting  to- 
gether. 

Another  phenomenon  in  palfies  is,  that  when  the  limbs  of  one 
fide  are  difabled,  thofe  of  the  other  are  in  perpetual  motion, 
This  can  only  be  explained  from  conceiving  that  the  power  of 
motion,  whatever  it  is,  or  wherever  it  refides,  and  which  is  capa- 
ble of  being  exhaufted  by  fatigue,  and  accumulated  in  reft,  is 
now  lefs  expended,  whilft  one  half  of  the  body  is  incapable  of 
receiving  its  ufual  proportion  of  it,  and  is  hence  derived  with 
greater  eafe  or  in  greater  abundance  into  the  limbs,  which  re- 
main unaffected 

H.  i.  The  excefs  or  defect  of  voluntary  exertion  produces 

fimilar 


SECT.  XXXIV.  2.  2.        OF  VOLITION.  337 

fimilar  effects  upon  the  fenfual  motions,  or  ideas  of  the  mind,  as 
thole  already  mentioned  upon  the  mufcular  fibres.  Thus  when 
any  violent  pain,  arifmg  from  the  defect  of  fome  peculiar  ftimu- 
lus,  exifts  either  in  the  mufcular  or  fenfual  fyftems  of  fibres,  and 
which  cannot  be  removed  by  acquiring  the  defective  (limulus  ; 
as  in  fome  conftitutions  convulfions  of  the  mufcles  are  produced 
to  procure  a  temporary  relief,  fo  in  other  conftitutions  vehement 
voluntary  exertions  of  the  ideas  of  the  mind  are  produced  for 
the  fame  purpofe  ;  for  during  this  exertion,  like  that  of  the  muf- 
cles, the  pain  either  vaniflies  or  is  diminifhed  :  this  violent  ex- 
ertion conftitutes  madnefs  ;  and  in  many  cafes  I  have  feen  the 
madnefs  take  place,  and  the  convulfions  ceafe,  and  reciprocally 
the  madnefs  ceafe,  and  the  convulfions  fupervene.  See  Section 
III.  5.  8. 

2.  Madnefs  is  diftinguifhable  from  delirium,  as  in  the  latter 
the  patient  knows  not  the  place  where  he  refides,  nor  the  per- 
fons  of  his  friends  or  attendants,  nor  is  confcious  of  any  external 
objects,  except  when  fpoken  to  with  a  louder  voice,  or  ftimu- 
lated  with  unufual  force,  and  even  then  he  foon  relapfes  into  a 
date  of  inattention  to  every  thing  about  him.  Whilft  in  the 
former  he  is  perfectly  fenfible  to  every  thing  external,  but  has 
the  voluntary  powers  of  his  mind  intentely  exerted  on  fome  par- 
ticular object  of  his  defire  or  averfion,  he  harbours  in  his 
thoughts  a  fufpicion  of  all  mankind,  left  they  ftiould  counteract 
his  defigns  ;  and  while  he  keeps  his  intentions,  and  the  motives 
of  his  actions  profoundly  fecret  ;  he  is  perpetually  ftudying  the 
means  of  acquiring  the  object  of  his  wifh,  or  of  preventing  or 
revenging  the  injuries  he  fufpects. 

3  A  late  French  phtlofopher,  Mr.  Helvetius,  has  deduced  al- 
moft  all  our  actions  from  this  principle  of  their  relieving  us 
from  the  ennui  or  tedium  vitse  ;  and  true  it  is,  that  our  defires 
or  averfions  are  the  motives  of  all  our  voluntary  actions  ;  and 
human  nature  feems  to  excel  other  animals  in  the  more  facile 
ufe  of  this  voluntary  power,  and  on  that  account  is  more  liable 
to  infanity  than  other  animals.  But  in  mania  this  violent  exer- 
tion of  volition  is  expended  on  miftaken  objefts,  and  would  not 
be  relieved,  though  we  were  to  gain  or  efcape  the  objects,  that 
excite  it.  Thus  I  have  feen  two  inftances  of  madmen,  who  con- 
ceived that  they  had  the  itch,  and  feveral  have  believed  they  had 
the  venereal  infection,  without  in  reality  having  a  fymptom  of 
cither  of  them.  They  have  been  perpetually  thinking  upon  this 
fubject,  and  fome  of  them  were  in  vain  falivated  with  defign  of 
convincing  them  to  the  contrary. 

4.  In  the  minds  of  mad  people  thofe  volitions  alone  exift, 
which  are  unmixed  with  fenfation  ;  immoderate  fufpicion  is 

VOL.  I.  1T  T  generally 


33 »  DISEASES          SECT.  XXXIV.  2. 5. 

generally  the  firft  fymptom,  and  want  of  fhame,  and  want  of 
delicacy  about  cleanlinefs.  Sufpicion  is  a  voluntary  exertion  of 
the  mind  arifing  from  the  pain  of  tear,  which  it  is  exerted  to 
relieve  :  fhame  is  the  name  of  a  peculiar  difagreeable  fenfation, 
fee  Fable  of  the  Bees,  and  delicacy  about  cleanlinefs  arifes  from 
another  difagreeable  fenfation.  And  therefore  are  not  found  in 
the  minds  of  maniacs,  which  are  employed  folely  in  voluntary 
exertions.  Hence  the  mod  modeft  women  in  this  difeafe  walk 
naked  amongft  men  without  any  kind  of  concern,  ufe  obfcene 
difcourfe,  and  have  no  delicacy  about  their  natural  evacuations. 

5.  Nor  are  maniacal  people  more  attentive  to  their  natural 
appetities,  or  to  the  irritations  whichfurround  them,  except  as  far 
as  may  refpedl  their  fufpicions  or  defigns  ;  for  the  violent  and 
perpetual  exertions  of  their  voluntary  powers  of  mind  prevent 
their  perception  of  almofl  every  other  object,  either  of  irritation 
or  of  fenfation.   Hence  it  is  that  they  bear  cold,  hunger,  and  fa- 
tigue, with  much  greater  pertinacity  than  in  their  fober  hours,  and 
are  lefs  injured  by  them  in  refpect  to  their  general  health.  Thus 
it  is  afierted  by  hiftorians,  that  Charles  the  Twelfth  of  Sweden 
ilept  on  the  fnow,  wrapped  only  in  his  cloak,  at  the  fiege  of  Fred- 
erickftadt,  and  bore  extremes  of  cold  and  hunger,  and  fatigue, 
under  which  numbers  of  his  folders  perifhed  ;  becaufe  the  king 
was  infane  with  ambition,  but  the  foldier  had  no  fuch  powerful 
ftimulus  to  preferve  his  fyftem  from  debility  and  death. 

6.  Befides  the  infanities  arifing  from  exertions  in  confequence 
of  pain,  there  is  alfo  a  pleafurable  infanity,  as  well  as  a  pleafura- 
ble  delirium  ;  as  the  infanity  of  perfonal  vanity,  and  that  of  re- 
Jigious  fanticifm.     When  agreeable  ideas  excite  into  motion  the 
fenforial  power  of  fenfation,  and  this  again  caufes  other  trains  of 
agreeable  ideas,  a  conftant  ftream  of  pleafurable  ideas  fucceeds, 
and  produces  pleafurable  delirium.  So  when  the  fenforial  power 
of  volition  excites  agreeable  ideas,  and  the  pleafure  thus  produ- 
ced excites  more  volition  in  its  turn,  a  conftant  flow  of  agreea- 
ble voluntary  ideas  fucceeds  \  which    when  thus  exerted  in  the 
extreme  conftitutes  infanity. 

Thus  when  our  mufcular  actions  are  excited  by  our  fenfations 
of  pleafure,  it  is  termed  play  ;  when  they  are  excited  by  our 
volition,  it  is  termed  work  ;  and  the  former  of  thefe  is  attended 
with  lefs  fatigue,  becaufe  the  mufcular  actions  in  play  produce 
in  their  turn  more  pleafurable  fenfation  ;  which  again  has  the 
property  of  producing  more  muicular  action,  An  agreeable  in- 
ftance  of  this  I  faw  this  morning.  A  little  boy,  who  was  tired 
w;fh  walking,  begged  of  his  papa  to  carry  him.  "  Here,"  faya 
the  reverend  doctor,  "  ride  upon  my  gold- headed  cane  ;"  and 
the  pleafed  child,  putting  it  between  his  legs,  gallopped  away 

with 


SECT.  XXXIV.  2. 7.        OF  VOLITION.  339 

with  delight,  and  complained  no  more  of  his  fatigue.  Here  the 
aid  of  another  fenforial  power,  that  of  pleafurable  fenfation,  fu- 
peradded  vigour  to  the  exertion  of  exhauiled  volition.  Which 
could  otherwife  only  have  been  excited  by  additional  pain,  as  by 
the  lafh  of  flavery.  On  this  account  where  the  whole  fenforial 
power  has  been  exerted  on  the  contemplation  of  the  promifed 
joys  of  heaven,  the  faints  of  all  perfecuted  religions  have  borne 
the  tortures  of  martyrdom  with  otherwife  unaccountable  firmnefs. 

7.  There  are  fome  difeafes,  which  obtain  at  lead  a  temporary 
relief  from  the  exertions  of  infanity  ;  many  inftances  of  dropfies 
being  thus  for  a  time  cured  are  recorded.     An  elderly  woman 
labouring  with  afcites  I  twice  faw  relieved  for  fome  weeks  by 
infanity,  the  dropfy  ceafed  for  feveral  weeks,  and  recurred  again 
alternating  with  the  infanity,     A  man  afflifted  with  difficult  ref- 
piration  on  lying  down,  with  very  irregular  pulfe,  and  cedema- 
tous  legs,  whom  I  faw  this  day,  has  for  above  a  week  been  much 
relieved  in  refpeft  to  all  thofe  fymptorns  by  the  accefllon  of  in- 
fanity, which  is  (hewn  by  inordinate  fufpicion,  and  great  anger. 

In  cafes  of  common  temporary  anger  the  increafed  aclion  of 
the  arterial  fyftem  is  feen  by  the  red  fkin,  and  increafed  pulfe, 
with  the  immediate  increafe  of  mufcular  activity.  A  friend  of 
mine,  when  he  was  painfully  fatigued  by  riding  on  horfeback, 
was  accuftomed  to  call  up  ideas  into  his  mind,  which  ufed  to  ex^ 
cite  his  anger  or  indignation,  and  thus  for  a  time  at  leait  relieved 
the  pain  of  fatigue.  By  this  temporary  infanity,  the  effecT:  of 
the  voluntary  power  upon  the  whole  of  his  fyftem  was  increafed; 
as  in  the  cafes  of  dropfy  above  mentioned,  it  would  appear,  that 
the  increafed  aclion  of  the  voluntary  faculty  of  the  fenfonum 
affe&ed  the  abforbent  fyftem,  as  well  as  the  fecerning  one. 

8.  In  refpect  to  relieving  inflammatory  pains,  and  removing 
fever,  I  have  feen  many  inftances,   as  mentioned  in  Sect.  XII. 
2. 4.     One  lady,  whom  I  attended,  had  twice  at  fome  years  in- 
terval a  locked  jaw,  which  relieved  a  pain  on  her  fternuin  with 
peripneumony.     Two  other  ladies  I  faw,  who  towards  the  end 
of  violent  peripneumony,  in   which  they  frequently  loft  blood, 
were  at  length    cured  by  infanity  fupervening.     In  the  former 
the  increafed  voluntary  exertion  of  the  mufcles  of  the  jaw,  in  the 
latter  that  of  the  organs  of  fenfe,  removed  the  difeafe  ;  that  is, 
the  difagreeable  fcnfation,    which  had  produced  the  inflamma- 
tion, now  excited  the  voluntary  power,  and  thefe  new  voluntary 
exertions   employed  or    expended  the  fuperabundant  fenforial 
power,  which  had  previoufly  been  exerted  on  the  arterial  fyftem, 
and  caufed  inflammation. 

s  Another  cafe  which  I  think  worth  relating,  was  of   a  young 
man    about  twenty;  he   had  laboured  under  an'  irritative  fe^er 

with 


340  DISEASES          SECT.  XXXIV.  3.  i, 

with  debility  for  three  or  four  weeks,  with  very  quick  and  very 
feeble  pulfe,  and  other  ufual  fymptoms  of  that  fpecies  of  typhus, 
but  at  this  time  complained  much  and  frequently  of  pain  of  his 
legs  and  feet.  When  thofe  who  attended  him  were  nearly  in 
defpair  of  his  recovery,  I  obferved  with  pleafure  an  infanity  of 
mind  fupervene  :  which  was  totally  different  from  delirium,  as 
he  knew  his  friends,  calling  them  by  their  names,  and  the  room 
in  which  he  lay,  but  became  violently  fufpicious  of  his  attend- 
ants, and  calumniated  with  vehement  oaths  his  tender  mother, 
who  fat  weeping  by  his  bed.  On  this  his  pulfe  became  flower 
and  firmer,  but  the  quicknefs  did  not  for  feme  time  entirely 
ceafe,  and  he  gradually  recovered.  In  this  cafe  the  introdu&ion 
of  an  increafed  quantity  of  the  power  of  volition  gave  vigour  to 
thofe  movements  of  the  fyftem,  which  are  generally  only  a6lu- 
ated  by  the  power  of  irritation,  and  of  aflbciation. 

Another  cafe  I  recoiled  of  a  young  man,  about  twenty-five, 
who  had  the  fcarlet-fever,  with  very  quick  pulfe,  and  an  univer- 
fal  eruption  on  his  Ikin,  and  was  not  without  reafon  efteemed  to 
be  in  great  danger  of  his  life.  After  a  few  days  an  infanity  fu- 
pervened,  which  his  friends  miftook  for  delirium,  and  he  gradu- 
ally recovered,  and  the  QUticle  peeled  off.  From  thefe  and  a 
few  other  cafes  I  have  always  efteemed  infanity  to  be  a  favoura- 
ble fign  in  fevers,  and  have  cautioufly  diftinguifhed  it  from  de- 
lirium. 

III.  Another  mode  of  mental  exertion  to  relieve  pain,  is  by 
producing  a  train  of  ideas  not  only  by  the  efforts  of  volition,  as 
in  infanity  ;  but  by  thofe  of  fenfation  likewife,  as  in  delirium 
and  fleep.  This  mental  effort  is  termed  reverie,  or  fomnambula- 
tion,  and  is  defcribed  more  at  large  in  Seft.  XIX  on  that  iub- 
jeftr  But  I  (hall  here  relate  another  cafe  of  that  wonderful  dif- 
eafe,  which  fell  yefterday  under  my  eye,  and  to  which  I  have 
feen  many  analogous  alienations  of  mind,  though  not  exadtly 
fimilar  in  all  circumftances.  But  as  all  of  them  either  began  or 
terminated  with  pain  or  convulfion,  there  can  be  no  doubt  but 
that  they  are  of  epileptic  origin,  and  conftitute  another  mode  of 
mental  exertion  to  relieve  fome  painful  fenfation. 

i.  Mailer  A.  about  nine  years  old,  had  been  feized  at  feven 
every  morning  for  ten  days  with  uncommon  fits,  and  had  had 
flight  returns  in  the  afternoon.  They  were  fuppofed  to  origin- 
ate from  worms,  and  had  been  in  vain  attempted  to  be  removed 
by  vermifuge  purges.  As  his  fit  was  expected  at  feven  yefter- 
day morning,  I  faw  him  before  that  hour  •,  he  was  afleep,  feemed 
free  from  pain,  and  his  pulfe  natural.  About  feven  he  began 
to  complain  of  pain  about  his  navel,  or  more  to  the  left  fide, 
and  in  a  few  minutes  had  exertions  of  his  arms  and  legs  like 

fwimming, 


SECT.  XXXIV.  3. 2.        OF  VOLITION,  34i 

fwimming.  He  then  for  half  an  hour  hunted  a  pack  of  hounds ; 
as  appeared  by  his  hallooing,  and  calling  the  dogs  by  their  names, 
and  difcourfing  with  the  attendants  of  the  chafe,  defcribing  ex- 
aftly  a  day  of  hunting,  which  (I  was  informed)  he  had  witnefled 
a  year  before,  going  through  all  the  mod  minute  circumftances 
of  it ;  calling  to  people,  who  were  then  prefent,  and  lamenting 
the  abfence  of  others,  who  were  then  alfo  abfent.  After  this 
fcene  he  imitated,  as  he  lay  in  bed,  fome  of  the  plays  of  boys, 
as  fwimming  and  jumping,  He  then  fung  an  Englifh  and  then 
an  Italian  fong  ;  part  of  which  with  his  eyes  open,  and  part  with 
them  clofed,  but  could  not  be  awakened  or  excited  by  any  vio- 
lence, which  it  was  proper  to  ufe. 

After  about  an  hour  he  came  fuddenly  to  himfelf  with  ap-r 
parent  furprife,  and  feemed  quite  ignorant  of  any  part  of  what 
had  pafied,  and  after  being  apparently  well  for  half  an  hour,  he 
fuddenly  fell  into  a  great  ftupor,  with  flower  pulfe  than  natural, 
and  a  flow  moaning  refpiration,  in  which  he  continued  about 
another  half  hour,  and  then  recovered. 

The  fcquel  of  this  difeafe  was  favourable ;  he  was  directed 
one  grain  of  opium  at  fix  every  morning,  and  then  to  rife  out  of 
bed  ;  at  half  pan:  fix  he  was  directed  fifteen  drops  of  laudanum 
in  a  glafs  of  wine  and  water.  The  firft  day  the  paroxyfin  be- 
came fhorter,  and  lefs  violent.  The  dofe  of  opium  was  increaf- 
ed  to  one  half  more,  and  in  three  or  four  days  the  fits  left  him. 
The  bark  and  filings  of  iron  were  alfo  exhibited  twice  a  day  ; 
and  I  believe  the  complaint  returned  no  more. 

2.  In  this  paroxyfin  it  mud  be  obferved,  that  he  began  with 
pain,  and  ended  with  (lupor,  in  both  circumftances  refernbling 
a  fit  of  epilepfy.  And  that  therefore  the  exertions  both  of  mind 
and  body,  both  the  voluntary  ones,  and  thofe  immediately  excited 
by  pieafurable  fenfation,  were  exertions  to  relieve  pain. 

The  hunting  fcene  appeared  to  be  rather  an  act  of  memory 
than  of  imagination,  and  was  therefore  rather  a  voluntary  exer- 
tion, though  attended  with  the  pieafurable  eagernefs,  which 
was  the  consequence  of  thofe  ideas  recalled  by  recollection,  and 
not  the  caufe  of  them. 

Thefe  ideas  thus  voluntarily  recollected  were  fucceeded  by  fen- 
fations  of  pleafure,  though  his  fenfes  were  unaffected  by  the 
ftimuli  of  vifible  or  audible  objects ;  or  fo  weakly  excited  by 
them  as  not  to  produce  fenfation  or  attention.  And  the  pleaf- 
ure thus  excited  by  volition  produced  other  ideas  and  other  mo- 
tions in  confequence  of  the  fenforial  power  of  fenfation. 
Whence  the  mixed  catentations  of  voluntary  and  fenfitive  ideas 
and  mqfcular  motions  in  reverie  j  which,  like  every  other  kind 

of 


342  DISEASES         SECT.  XXXIV.  3. 3. 

of  vehement  exertion,  contribute  to  relieve  pain,  by  expending 
a  large  quantity  of  fenforial  power. 

Thofe  fits  generally  commence  during  fleep,  from  whence  I 
fuppofe  they  have  been  thought  to  have  fome  connexion  with 
fleep,  and  have  thence  been  termed  Somnambulifm  ;  but  their 
commencement  during  fleep  is  owing  to  our  increafed  excita- 
bility by  internal  fenfations  at  that  time,  as  explained  in  Se£h 
XVIII.  14  and  15,  and  not  to  any  fimilitude  between  reverie 
and  fleep. 

3.  I  was  once  concerned  for  a  very  elegant  and   ingenious 
young  lady,  who  had  a  reverie  on  alternate  days,  which  continu- 
ed nearly  the  whole  day  ;  and  as  in  her  days  of  difeafe  fhe  took 
up  the  fame  kind  of  ideas,   which  fhe  had  converfed  about  on 
the  alternate  day  before,  and  could  recollect  nothing  of  them  on 
her  well  day  ;  fhe  appeared  to  her  friends  to  poflfefs  two  minds. 
This  cafe  alfo  was  of  the  epileptic  kind,  and  was  cured,  with 
fome  relapfes,  by  opium  adminiftered  before  the  commencement 
of  the  paroxyfm. 

4.  Whence  it  appears,  that  the  methods  of  relieving  inflam- 
matory pains,  is  by  removing  all  ftimulus,  as  by  venefection, 
cool  air,  mucilaginous  diet,  aqueous  potation,  filence,  darknefs. 

The  methods  of  relieving  pains  from  defeat  of  ftimulus  is  by 
fupplying  the  peculiar  ftimulus  required,  as  of  food  or  warmth. 

And  the  general  method  of  relieving  pain  is  by  exciting  into 
aftion  fome  great  part  of  the  fyftem  for  the  purpofe  of  expend- 
ing a  part  of  the  fenforial  power.  This  is  done  either  by  ex- 
ertion of  the  voluntary  ideas  and  mufcles,  as  in  infanity  and 
convulfion ;  or  by  exerting  both  voluntary  and  fenfitive  mo- 
tions, as  in  reverie ;  or  by  exciting  the  irritative  motions  by 
wine  or  opium  internally,  and  by  the  warm  bath  or  blifters  ex- 
ternally ;  or  laftly,  by  exciting  the  fenfitive  ideas  by  good  news, 
afiefting  ftories,  or  agreeable  paffions. 


SECT. 


SfiCT.XXXV.  i.  i.          ASSOCIATION.  343 


SECT.      XXXV. 

DISEASES    OF    ASSOCIATION. 

L  i.  Sympathy  or  confent  of  parts.  Primary  and  fecondary  parts 
of  an  officiated  train  of  motions  reciprocally  affect  each  other. 
Parts  of  irritative  trains  of  motion  affect  each  other  in  four  ways. 
Sympathies  of  thejkin  and  flomach.  Flujhing  of  the  face  after  a 
meal.  Eruption  of  the  fmall-pox  on  the  face.  Chilnefs  after  a 
meal.  2.  Vertigo  from  intoxication.  3.  Abforption  from  the 
lungs  and  pericardium  by  emetics.  In  vomiting  the  ablions  of  the 
Jlomach  are  decreafed^  not  increafed.  Digejlionflrengthened  after 
an  emetic.  Vomiting  from  deficiency  of  fenforial  power.  4. 
Dyfpnaafrom  cold  bathing.  S/oiv  pulfe  from  digitalis.  Death 
from  gout  in  the  flomach  II.  I.  Primary  and  fecondary  parts 
of  fenfitive  affbciations  affecl  each  other.  Pain  from  gail-Jlone^ 
from  urinary  Jlone.  Hemicrania.  Painful  epilepfy  2.  Gout 
and  red  face  from  inflamed  liver  Shingles  from  inflamed  kidney. 
3.  Cor yza  from  cold  applied  to  the  feet.  Hepatitis.  4.  Pain  of 
Jhoulders  from  inflamed  liver.  III.  Difeafesfrom  the  affilia- 
tions of  ideas. 

I.  i.  MANY  fynchronous  and  fucceflive  motions  of  our  muf- 
cular  fibres,  and  of  our  organs  of  fenfe,  or  ideas,  become  affoci- 
ated  fo  as  to  form  indiffolubie  tribes  or  trains  of  a£Uon,  as  fliewn 
in  Section  X.  on  Aflbciate  Motions.  Some  conftiturions  more 
eafily  eftablifh  thefe  aflbciations,  whether  by  voluntary,  fenfi- 
tive, or  irritative  repetitions,  and  fome  more  eafily  lofe  them 
again,  as  (hewn  in  Section  XXXI.  on  Temperaments. 

When  the  beginning  of  fuch  a  train  of  adtions  becomes  by 
any  means  difordered,  the  fucceeding  part  is  liable  to  become 
difturbed  in  confequence,  and  this  is  commonly  termed  fympa- 
thy  or  confent  of  parts  by  the  writers  of  medicine.  For  the 
more  clear  underftanding  of  the  fympathies  we  mud  confider 
a  tribe  or  train  of  a£tions  as  divided  into  two  parts,  and  call  one 
of  them  the  primary  or  original  motions,  and  the  other  the 
fecondary  or  fympathetic  ones. 

The  primary  and  fecondary  parts  of  a  train  of  irritative  actions 
may  reciprocally  affect  each  other  in  four  different  manners. 

1.  They  may  both  be  exerted  with  greater  energy  than  natural. 

2.  The  former   may    act  with  greater,   and  the  latter  with  lefs 
energy.     3.  The  former  may  act  with  lefs,  and  the  latter  with 
greater  energy      4.  They  may    both  act  with  lefs  energy  than 
natural,     I   ftiajl  now  give  an  example  of  each  kind  of  thefe 

modes 


244  DISEASES  SECT.  XXXV.  i.  2 

modes  of  action,  and  endeavour  to  {hew,  that  though  the  pri- 
mary and  fecondary  parts  of  thefe  trains  or  tribes  of  motion  are 
connected  by  irritative  aflbciation,  or  their  previous  habits  of 
ading  together,  as  defcribed  in  Ser'l.  XX.  on  Vertigo.  Yet 
that  their  a£ling  with  fimilar  or  diiiimilar  degrees  of  energy, 
depends  on  the  greater  or  lefs  quantity  of  fenforial  power,  which 
the  primary  part  of  the  train  expends  in  its  exertions. 

The  a£lions  of  the  (lomach  conftitute  fo  important  a  part  of 
the  aflbciations  of  both  irritative  and  fenfitive  motions,  that  it  is 
faid  to  fympathize  with  almoft  every  part  of  the  body  ;  the  firfl 
example,  which  I  (hall  adduce  to  fhew  that  both  the  primary 
and  fecondary  parts  of  a  train  of  irritative  aflbciations  of  motion 
a£t  with  increafed  energy,  is  taken  from  the  confent  of  the  fkui 
with  this  organ.  When  the  a£Hon  of  the  fibres  of  the  (lomach 
is  increafed,  as  by  the  flimulus  of  a  full  meal,  the  exertions  of 
the  cutaneous  arteries  of  the  face  become  increafed  by  their  ir- 
ritative aflbciations  with  thofe  of  the  ftomach,  and  a  glow  or 
flufhing  of  the  face  fucceeds.  For  the  finall  veffels  of  the  ikin 
of  the  face  having  been  more  accuftomed  to  the  varieties  of  ac- 
tion,from  their  frequent  expofure  to  various  degrees  of  cold  and 
heat,  become  more  eafily  excited  into  increafed  aciion,  than  thofe 
of  the  covered  parts  of  our  bodies,  and  thus  ac~l  with  more  ener- 
gy from  their  irritative  or  fenfitive  aflbciations  with  the  ftom- 
ach.  On  this  account  in  fmall-pox  the  eruption  in  confequence 
of  the  previous  affection  of  the  ilomach  breaks  out  a  day  foonej 
on  the  face  than  on  the  hands,  and  two  days  fooner  than  on  the 
trunk,  and  recedes  in  fimilar  times  after  maturation. 

But  fecondly,  in  weaker  conftitutions,  that  is,  in  thofe  who 
poffefs  lefs  fenforial  power,  fo  much  of  it  is  expended  in  the  in- 
creafed actions  of  the  fibres  of  the  ftomach  excited  by  the  ftimu- 
iusof  a  meal,  that  a  fenfe  of  chilnefs  fucceeds  inftead  of  the  uni- 
verfal  glow  above  mentioned  ;  and  thus  the  fecondary  part  of 
the  aflbciated  train  of  motions  is  diminifhed  in  energy,  in  con- 
fequence  of  the  increafed  a&ivity  of  the  primary  part  of  it. 

2.  Another  inftance  of  a  fimilar  kind,  where  the  fecondary 
part  of  the  train  a&s  with  lefs  energy  in  confequence  of  the 
greater  exertions  of  the  primary  part,  is  the  vertigo  attending  in- 
toxication ;  in  this  circumftance  fo  much  fenforial  power  is  ex- 
pended on  the  ftomach,  and  on  its  neareft  or  more  ftrongly  aflb- 
ciated motions,  as  thofe  of  the  fubcutaneous  veflels,  and  proba- 
bly of  the  membranes  of  fome  internal  vifcera,  that  the  irritative 
motions  of  the  retina  become  imperfe£Uy  exerted  from  defi- 
ciency of  fenforial  power,  as  explained  in  Sed.  XX.  and  XXL 
3. on  Vertigo  and  on  Drunkennefs,  and  hence  the  Daggering  ine- 
briate cannot  completely  balance  himfelf  by  fuchindiftincT;  vifion. 

q.  An 


SECT.  XXXV.  1.3.      OF  ASSOCIATION.  345 

3.  An  inftance  of  the  third  circumftance,  where  the  primary 
part  of  a  train  of  irritative  motions  a£ts  with  lefs,  and  the  fec- 
ondary  part  with  greater  energy,  may  be  obferved  by  making 
the  following  experiment.  If  a  perfon  lies  with  his  arms  and 
(boulders  out  of  bed,  till  they  become  cold,  a  temporary  coryza 
or  catarrh  is  produced  ;  fo  that  the  pafTage  of  the  noftrils  be- 
€omes  totally  obftrufted  ;  at  leaft  this  happens  to  many  people  j 
and  then  on  covering  the  arms  and  (boulders,  till  they  become 
warm,  the  paflage  of  the  noftrils  ceaies  again  to  be  obftru&ed, 
and  a  quantity  of  mucus  is  difcharged  from  them.  In  this  cafe 
the  quiefcence  of  the  veflels  of  the  fkin  of  the  arms  and  ilioul- 
ders,  occafioned  by  expofure  to  cold  air,  produces  by  irritative 
aflbciation  an  increafed  a£Hon  of  the  veflels  of  the  membrane  of 
the  noftrils ;  and  the  accumulation  of  fenforial  power  during 
the  torpor  of  the  arms  and  (boulders  is  thus  expended  in  produc- 
ing  a  temporary  coryza  or  catarrh. 

Another  inftance  may  be  adduced  from  the  fympathy  or  con- 
fent  of  the  motions  of  the  ftomach  with  other  more  diftant  links 
of  the  very  extenfive  tribes  or  trains  of  irritative  motions  aflbci- 
ated  with  them,  defcribed  in  Sedt.  XX.  on  Vertigo.  When 
the  adlions  of  the  fibres  of  the  ftomach  are  diminifhed  or  invert- 
ed, the  actions  of  the  abforbent  veflels,  which  take  up  the  mucus 
from  the  lungs,  pericardium,  and  other  cells  of  the  body,  be- 
come increafed,  and  abforb  the  fluids  accumulated  in  them  with 
greater  avidity,  as  appears  from  the  exhibition  of  foxglove,  anti- 
mony, or  other  emetics,  in  cafes  of  anafarca,  attended  with  un- 
equal pulfe  and  difficult  refpiration. 

That  the  aft  of  naufea  and  vomiting  is  a  decreafed  exertion 
of  the  fibres  of  the  ftomach  may  be  thus  deduced  ;  when  an 
emetic  medicine  is  adminiftered,  it  produces  the  pain  of  ficknefsj 
as  a  difagreeable  tafte  in  the  mouth  produces  the  pain  of  naufea  ; 
thefe  pains,  like  that  of  hunger,  or  of  cold,  or  like  thofe,  which 
are  ufually  termed  nervous,  as  the  head-ach  or  hemicrania,  do 
not  excite  the  organ  into  greater  a£Hon  ;  but  in  this  cafe  I  im- 
agine the  pains  of  ficknefs  or  of  naufea  counteract  or  deftroy 
the  pleafurable  ferifation,  which  feems  neceflary  to  digeftion,  at, 
(hewn  in  Seft.  XXXIII.  i.  i.  The  periftaltic  motions  of  the 
fibres  of  the  ftomach  become  enfeebled  by  the  want  of  this 
ftimulus  of  pleafurable  fenfation,  and  in  confequence  itop  for  a 
time,  and  then  become  inverted  ;  for  they  cannot  become  invert- 
ed without  being  previoufly  flopped.  Now  that  this  inverfion 
of  the  trains  of  motion  of  the  fibres  of  the  ftomach  is  owing  to 
the  deficiency  of  pleafurable  fenfation  is  evinced  from  this  cir- 
cumftance, that  a  naufeous  idea  excited  by  words  will  produce 
vomiting  as  effectually  as  a  naufoeus  drug. 

VOL.  I.  W  w  Hence 


DISEASES  SECT.  XXXV.  i.  4, 

Hence  it  appears,  that  the  aft  of  naufea  or  vomiting  expends 
lefs  fenforial  power  than  the  ufual,  periftaltic  motions  of  the 
ftomach  in  the  digeftion  of  our  aliment  ;  and  that  hence  there 
Is  a  greater  quantity  of  fenforial  power  becomes  accumulated 
in  the  fibres  of  the  ftomach,  and  more  of  it  in  confequence  to 
{pare  for  the  aft  ion  of  thofe  parts  of  the  fyftem,  which  are  thus 
aflbciated  with  the  ftomach,  as  of  the  whole  abforbent  feries  of 
veffels,  and  which  are  at  the  fame  time  excited  by  their  ufual 
ftimuli. 

From  this  we  can  underftand,  how  after  the  operation  of  an 
emetic  the  ftomach  becomes  more  irritable  and  fenfible  to  the 
ftimulus,  and  the  pleafure  of  food  ;  fmce  as  the  fenforial  power 
becomes  accumulated  during  the  naufea  and  vomiting,  the  digef- 
tive  power  is  afterwards  exerted  more  forcibly  for  a  time.  It 
fhould,  however,  be  here  remarked,  that  though  vomiting  is  in 
general  produced  by  the  defeft  of  thi$  ftimuius  of  pleafurable 
fenfation,  as  when  a  naufeous  drug  is  adminiltered  ;  yet  in  long- 
continued  vomiting,  as  in  fea-ficknefs,  or  from  habitual  dram- 
drinking,  it  arifes  from  deficiency  of  fenforial  power,  which  in 
the  former  cafe  is  exhaufted  by  the  increafed  exertion  of  the  ir- 
ritative ideas  of  vifion,  and  in  the  latter  by  the  frequent  applica- 
tion of  an  unnatural  ftimulus. 

4.  An  example  of  the  fourth  circumftance  above  mentioned, 
where  both  the  primary  and  fecondary  parts  of  a  train  of  mo- 
tions proceed  with  energy  lefs  than  natural,  may  be  obferved  in 
the  dyfpnosa,  which  occurs  on  going  into  a  very  cold  bath,  and 
which  has  been  defcribed  and  explained  in  Seft.  XXXII.  3,  2. 
And  by  the  increafed  debility  of  the  pulfations  of  the  heart 
and  arteries  during  the  operation  of  an  emetic.  Secondly,  from 
the  flownefs  and  intermillion  of  the  pulfations  of  the  heart  from 
the  inceffant  efforts  to  vomit  occafioned  by  an  over-dofe  of  dig- 
italis. And  thirdly,  from  the  total  ftoppage  of  the  motions  of 
the  heart,  or  death,  iri  confequence  of  the  torpor  of  the  ftom- 
ach, when  affected  with  the  commencement  or  cold  paroxyfin 
of  the  gout.  See  Seft.  XXV.  1 7. 

II.  i .  The  primary  and  fecondary  parts  of  the  trains  of  fen- 
litive  affociation  reciprocally  affeft  each  other  in  different  man- 
ners, i .  The  increafed  fenfation  of  the  primary  part  may  ceafe, 
when  that  of  the  fecondary  part  commences.  2*  The  increafed 
aftion  of  the  primary  part  may  ceafe,  when  that  of  the  fecondary 
part  commences.  3.  The  primary  part  may  have  increafed  fen- 
fation, and  the  fecondary  part  increafed  aftion.  4.  The  pri- 
mary part  may  have  increafed  aftion,  and  the  fecondary  part  in- 
creafed fenfation. 

Examples  of  the  firft  mode,  where  the  increafed  fenfation  of 

tbe 


SECT.  XXXV.  2.  r.      OF  ASSOCIATION.  347 

the  primary  part  of  a  train  of  fenfitive  aflbciation  ceafes,  when 
that  of  the  fecondary  part  commences,  are  not  unfrequent  ;  as 
this  is  the  general  origin  of  thofe  pains,  which  continue  fome 
time  without  being  attended  with  inflammation,  fuch  as  the  pain 
at  the  pit  of  the  flomach  from  a  (tone  at  the  neck  of  the  gall- 
bladder, and  the  pain  of  (Irangury  in  the  glaris  penis  from  a  (lone 
at  the  neck  of  the  urinary  bladder.  In  both  thefe  cafes  the  part 
which  is  aftedted  fecondarily,  is  believed  to  be  much  more  fen- 
fible  than  the  part  primarily  affected,  as  defcribed  in  the  cata- 
logue of  difeafes,  Clafs  II.  i.  i.  1 1.  and  IV.  2.  2.  2.  and  IV. 
2.  2.  4. 

The  hemicrania,  or  nervous  head-ach,  as  it  is  called,  when  it 
originates  from  a  decaying  tooth,  is  another  difeafe  of  this  kind  ; 
as  the  pain  of  the  carious  tooth  always  ceafes,  when  the  pain 
over  one  eye  and  temple  commences.  And  it  is  probable,  that 
the  violent  pains,  which  induce  convulfions  in  painful  epilepfies, 
are  produced  in  the  fame  manner,  from  a  more  fenfible  part 
fympathizing  with  a  difeafed  one  of  lefs  fenfibility.  See  Cata- 
logue of  difeafes,  Clafs  IV.  2  2  8.  and  III.  I.  I.  6. 

The  lad  tooth,  or  dens  fapientix,  of  the  upper  jaw  moft  fre- 
quently decays  firii,  and  is  liable  to  produce  pain  over  the  eye 
and  temple  of  that  fide.  The  lad  tooth  of  the  under  jaw  is  alfo 
liable  to  produce  a  fimilar  hemicrania,  when  it  begins  to  decay. 
When  a  tooth  in  the  upper  jaw  is  the  caufe  of  the  headach,  a 
{lighter  pain  is  fometimes  perceived  on  the  cheek-bone.  And 
when  a  tooth  in  the  lower  jaw  is  the  caufe  of  headach,  a  pain 
ibmetimes  affects  the  tendons  of  the  mufcles  of  the  neck,  which 
are  attached  near  the  jaws.  But  the  clavus  hyftericus,  or  pain 
about  the  middle  of  the  parietal  bone  on  one  fide  of  the  head,  I 
have  feen  produced  by  the  fecond  of  the  molares,  or  grinders,  of 
the  under  jaw  j  of  which  I  (hall  relate  the  following  cafe.  See 
Clafs  IV.  2.  2.  8. 

Mrs- ,  about  30  years  of  age,  was  feized  with  great  pain 

about  the  middle  of  the  right  pariecal  bone,  which  had  continu- 
ed a  whole  duy  before  I  faw  her,  and  was  fo  violent  as  to  threat- 
en to  occafion  convulfions.  Not  being  able  to  deleft  a  decay- 
ing tooth,  or  a  tender  one,  by  examination  with  my  eye,  or  by 
{Inking  them  with  a  tea-fpoon,  and  fearing  bad  confequences 
from  her  tendency  to  convulfion,  I  advifed  her  to  extract  the 
laft  tooth  of  the  under  jaw  on  the  affefted  fide  ;  which  was 
done  without  any  good  effect.  She  was  then  dire&ed  to  lofe 
blood,  and  to  take  a  brifk  cathartic  ;  and  after  that  had  operated, 
about  60  drops  of  laudanum  were  given  her,  with  large  dofes 
of  bark  ;  by  which  the  pain  was  removed.  In  about  a  fortnight 
fhe  took  a  cathartic  medicine  by  ill  advice,  and  the  pain  returned 

with 


348  DISEASES  SECT.  XXXV.  2.  r, 

with  greaf-er  violence  in  the  fame  place  ;  and,  before  I  could  ar- 
rive, as  fhe  lived  30  miles  from  me,  (he  fuffered  a  paralytic 
ftroke  ;  which  affefted  her  limbs  and  her  face  on  one  fide,  and 
relieved  the  pain  of  her  head. 

About  a  year  afterwards  I  was  again  called  to  her  on  account 
of  a  pain,  as  violent  as  before,  exactly  on  the  fame  part  of  the 
other  parietal  bone.  On  examining  her  mouth  I  found  the  fecond 
molaris  of  the  under  jaw  on  the  fide  before  affe&ed  was  now- 
decayed,  and  concluded  that  this  tooth  had  occafioned  the  ftroke 
of  the  palfy  by  the  pain  and  confequent  exertion  it  had  caufed. 
On  this  account  I  earneftly  entreated  her  to  allow  the  found  mo- 
laris  of  the  fame  jaw  oppofite  to  the  decayed  one  to  be  extraft- 
ed  ;  which  was  forthwith  done,  and  the  pain  of  her  head  im- 
mediately ceafed,  to  the  aftonifhment  of  her  attendants. 

In  the  cafes  above  related  of  the  pain  exifting  in  a  part  dif- 
tant  from  the  feat  of  the  difeafe,  the  pain  is  owing  to  defe£l  of 
the  ufual  motions  of  the  painful  part.  This  appears  from  the 
coldnefs,  palenefs,  and  emptinefs  of  the  affetted  veffels,  or  of 
the  extremities  of  the  body  in  general,  and  from  there  being  no 
tendency  to  inflammation.  The  increafed  a£Uon  of  the  prima- 
ry part  of  thefe  aflbciated  motions,  as  of  the  hepatic  termination 
of  the  bile-duft  from  the  ftimulus  of  a  gall-ftone,  or  of  the  inte- 
rior termination  of  the  urethra  from  the  ftimulus  of  a  ftone  in 
the  bladder,  or  laftly,  of  a  decaying  tooth  in  hemicrania,  de- 
prives the  fecondary  part  of  thefe  aflbciated  motions,  namely, 
the  exterior  terminations  of  the  bile-dudl  or  urethra,  or  the  pain- 
ed membranes  of  the  head  in  hemicrania,  of  their  natural  fhare 
of  fenforial  power  :  and  hence  the  fecondary  parts  of  thefe  fen- 
fitive  trains  of  affbciation  become  pained  from  the  deficiency  of 
their  ufual  motions,  which  is  accompanied  with  deficiency  of 
fecretions  and  of  heat.  See  Sett  IV.  5.  XII.  5.  3.  XXXIV.  i. 

Why  does  the  pain  of  the  primary  part  of  the  aflbciation 
ceafe,  when  that  of  the  fecondary  part  commences  ?  This  is  a 
queftion  of  intricacy,  but  perhaps  not  inexplicable.  The  pain 
of  the  primary  part  of  thefe  aflbciated  trains  of  motion  was  ow- 
ing to  too  great  ftimulus,  as  of  the  ftone  at  the  neck  of  the  blad- 
der, and  was  confequently  caufed  by  too  great  adlion  *of  the 
pained  part.  This  greater  aftion  than  natural  of  the  primary 
part  of  thefe  aflbciated  motions,  by  employing  or  expending  the 
fenforial  power  of  irritation  belonging  to  the  whole  aflbciated 
train  of  motions,  occafioned  torpor,  and  confequent  pain  in 
the  fecondary  part  of  the  aflbciated  train  j  which  was  poflefled 
of  greater  fenfibility  than  the  primary  part  of  it.  Now  the  great 
pain  of  the  fecondary  part  of  the  train,  as  foon  as  it  commences, 
employs  or  expends  the  fenforial  power  of  fenfation  belonging 

to 


SECT.  XXXV.  2.  i.      OF  ASSOCIATION.  349 

to  the  whole  aflbciated  train  of  motions  ;  and  in  confequence 
the  motions  of  the  primary  part,  though  increafed  by  the  ftim- 
ulus  of  an  extraneous  body,  ceafe  to  be  accompanied  with  pain 
or  fenfation. 

If  this  mode  of  reafoning  be  juft  it  explains  a  curious  fact, 
why  when  two  parts  of  the  body  are  ftrongly  ftimulated,  the 
pain  is  only  felt  in  one  of  them,  though  it  is  poflible  by  volunta- 
ry attention  it  may  be  alternately  perceived  in  them  both.  In 
the  fame  manner,  when  two  new  ideas  are  prefented  to  us  from 
the  ftimulus  of  external  bodies,  we  attend  to  but  one  of  them  at 
a  time.  In  other  words,  when  one  fet  of  fibres,  whether  of  the 
mulcles  or  organs  of  ienfe,  contract  fo  ftrongly  as  to  excite 
much  fenfation  ;  another  fet  of  fibres  contracting  more  weakly 
do  not  excite  fenfation  at  all,  becaufe  the  fenforial  power  of  fen- 
fation is  pre-occupied  by  the  firft  fet  of  fibres.  So  we  cannot 
will  more  than  one  effect  at  once,  though  by  aflbciations  previ- 
oufly  formed  we  can  move  many  fibres  in  combination. 

Thus  in  the  inftances  above  related,  the  termination  of  the 
bile-duct  in  the  duodenum,  and  the  exterior  extremity  of  the 
urethra,  are  more  fenfible  than  their  other  terminations.  When 
thefe  parts  are  deprived  of  their  ufual  motions  by  deficiency  of 
fenforial  power,  as  above  explained,  they  become  painful  ac- 
cording to  law  the  fifth  in  Section  IV.  and  the  lefs  pain  orig- 
inally excited  by  the  ftimulus  of  concreted  bile,  or  of  a  (tone  at 
their  other  extremities  ceafes  to  be  perceived.  Afterwards,  how- 
ever, when  the  concretions  of  bile,  or  the  ftone  in  the  urinary 
bladder,  become  more  numerous  or  larger,  the  pain  from  their 
increafed  ftimulus  becomes  greater  than  the  aflbciated  pain ;  and 
is  then  felt  at  the  neck  of  the  gall-bladder  or  urinary  bladder  ; 
and  the  pain  of  the  glans  penis,  or  at  the  pit  of  the  ftomach, 
ceafes  to  be  perceived. 

2.  Examples  of  the  fecond  mode,  where  the  increafed  action 
of  the  primary  part  of  a  train  of  fenfitive  aflbciation  ceafes,  when 
that  of  the  fecondary  part  commences,  are  alfo  not  unfrequent ; 
as  this  is  the  ufual  manner  of  the  tranflation  of  inflammations 
from  internal  to  external  parts  of  the  fyftem,  fuch  as  when  an 
inflammation  of  the  liver  or  ftomach  is  tranflated  to  the  mem- 
branes of  the  foot,  and  forms  the  gout  ;  or  to  the  fkin  of  the 
face,  and  forms  the  rofy  drop  ;  or  when  an  inflammation  of  the 
membranes  of  the  kidneys  is  tranflated  to  the  fkin  of  the  loins, 
and  forms  one  kind  of  herpes,  called  (hinglcs  5  in  thefe  cafes  by 
whatever  caufe  the  original  inflammation  may  have  been  pro- 
duced, as  the  fecondary  part  of  the  train  of  fenfitive  aflbciation 
is  more  fenfible,  it  becomes  exerted  with  greater  violence  than 
»the  firft  part  of  it ;  and  by  both  its  increufed  pain,  and  the  in- 

creafed 


35o  DISEASES         SECT.  XXXV.  2.  3 , 

» 

creafed  motion  of  its  fibres,  fo  far  diminifhes  or  exhaufts  the  feti- 
forial  power  of  fenfation  ;  that  the  primary  part  of  the  train  be- 
ing lefs  fenfible  ceafes  both  to  feel  pain,  and  to  act  with  un- 
natural energy. 

3.  Examples  of  the  third  mode,  where  the  primary  part  of  a 
train  of  fenfitive  affociation  of  motions  may  experience  increafed 
fenfation,  and  the  fecondary  part  increafed  action,  are  likewife 
not  unfrequent  ;  as  it  is  in  this  manner  that  mod  inflammations 
commence.     Thus,  after  (landing  fome  time  in  fnow,  the  feet 
become  affected  with  the  pain  of  cold,   and  a  common  coryza, 
or  inflammation   of  the  membranes  of  the  noftrils,    fucceeds. 
It  is  probable  that  the  internal  inflammations,  as  pleurifes,  or  he- 
patitis,  which  are  produced  after  the  cold  paroxyfm  of  fever, 
originate  in  the  fame  manner  from  the  fympathy  of  thofe  parts 
with  fome  others,  which  were  previouily  pained   from  quief- 
cence  ;  as  happens  to  various  parts  of  the  fyftem  during  the  cold 
fits  of  fevers.     In  thefe  cafes  it  would  feem,    that  the  fenforial 
power  of  fenfation  becomes  accumulated  during  the  pain  of  cold, 
as  the  torpor  of  the  veflels  occafioned  by  the  defect  of  heat  con- 
tributes to  the  increafe  or  accumulation  of  the  fenforial  power  of 
irritation,  and  that  both  thefe  become  exerted  on  fome  internal 
part,  which  was  not  rendered  torpid  by  the  cold  which  affected 
the  external  parts,  nor  by  its  affociation  with  them  ;  or  which 
fooner  recovered  its  fenfibility.     This  requires  further  confid- 
eration. 

4.  An  example  of  the  fourth  mode,  or  where  the  primary 
part  of  a  fenfitive  affociation  of  motions  may  have  increated  ac- 
tion, and  the  fecondary  part  increafed  fenfation,  may   be  taken 
from  the  pain  of  the  fhoulder,  which  attends  inflammation  of  the 
membranes  of  the  liver,  fee  Clafs  IV.  2.  2.  9  ;  in  this  circum- 
fiance  fo  much  fenforial  power  feems  to  be  expended  in  the  vio- 
lent actions  and  fenfations  of   the   inflamed  membranes  of  the 
liver,  that  the  membranes  affociated  with  them  become  quief- 
cent  to  their  ufual  flimuli,  and  painful  in  confequence. 

There  may  be  other  modes  in  which  the  primary  and  feconda- 
ry parts  of  the  trains  of  affociated  fenfitive  motions  may  recipro- 
cally affect  each  other,  as  may  be  feen  by  looking  over  Clafs  IV. 
in  the  catalogue  of  difeafes  ;  all  which  may  probably  be  refolved 
into  the  plus  and  minus  of  fenforial  power,  but  we  have  not  yet 
had  fufficient  obfervations  made  upon  them  with  a  view  to  this 
doclrine. 

III.  The  affociated  trains  of  our  ideas  may  have  fympathies, 
and  their  primary  and  fecondary  parts  affect  each  other  in  fome 
manner  fimilarto  thofe  above  defcribed  ;  and  may  thus  occafiou 
various  curious  phenomena  not  yet  adverted  to,  befides  thofe  ex, 

plained 


SECT.  XXXV.  3.1.      OF  ASSOCIATION.  351 

plained  in  the  Sections  on  Dreams,  Reveries,  Vertigo,  and 
Drunkennefs  -,  and  may  thus  difturb  the  deductions  of  our  rea- 
fonings,  as  well  as  the  ftreams  of  our  imaginations  :  prefent  us 
with  falfe  degrees  of  fear,  attach  unfounded  value  to  trivial  cir- 
cumftances  ;  give  occafion  to  our  early  prejudices  and  antipa- 
thies ;  and  thus  embarrafs  the  happinefs  of  our  lives.  A  copi- 
ous and  curious  harveft  might  be  reaped  from  this  province  of 
fcience,  in  which,  however,  I  (hall  not  at  prefent  wield  my 
fickle. 


SECT, 


PERIODS  SECT.  XXXVI.  i.  i, 

SEC  TV     XXXVI. 

OF    THE    PERIODS    OF    DISEASES. 

I.  Mufcles  excited  by  volition  focn  ceafe  to  contracl,  or  by  fenfation, 
or  by  irritation,  owing  to  the  exhauftion  of  fenforial power.  Muf- 
cles fubjecledto  lefs  Jlimulus  have  their  fenforial  power  accumula- 
ted. Hence  the  periods  of  feme  fevers.  Want  of  irritability 
after  intoxication*  II.  I.  Natural  aclions  catenated  with  daily 
habits  of  life.  2  With  folar  periods.  Periods  of  Jleep.  Of 
evacuating  the  bowels.  3.  Natural  aclions  catenated  with  lunar 
periods.  M.enjlruation.  Venereal  orgafm  of  animals*  Barren- 
nefs.  III.  Periods  of  difeafed  animal  aftions  from  Jiated  returns 
of  noclurnal  cold,  from  folar  and  lunar  influence.  Periods  of 
diurnal  fever,  heclic  fever,  quotidian,  tertian,  quartan  fever. 
Periods  of  gout,  pleurify,  of  fevers  with  arterial  debility,  and  with 
arterial jlrength.  Periods  of  rhaphania,  of  nervous  cough,  hemi- 
crania,  arterial  hemorrhages,  hemorrhoids,  hamoptoc,  epilepfy^ 
palfy,  apoplexy,  madnefs.  IV.  Critical  days  depend  on  lunar 
periods.  Lunar  periods  in  the  f mall-pox. 

I.  IF  any  of  our  mufcles  be  made  to  contract  violently  by  the 
power  of  volition,  as  thofe  of  the  fingers,  when  any  one  hangs 
by  his  hands  on  a  fwing,  fatigue  foon  enfues  ;  and  the  mufcles 
ceafe  to  act  owing  to  the  temporary  exhauftion  of  the  fpirit  of 
animation  ;  as  foon  as  this  is  again  accumulated  in  the  n^ufcles, 
they  are  ready  to  contract  again  by  the  efforts  of  volition. 

Thofe  violent  mufcular  actions  induced  by  pain  become  in 
the  fame  manner  intermitted  and  recurrent ;  as  in  labour-pains, 
vomiting,  tenefmus,  ftrangury  ;  owing  likewife  to  the  temporary 
exhauftion  of  the  fpirit  of  animation,  as  above  mentioned. 

When  any  ftimulus  continues  long  to  acl  with  unnatural  vi- 
olence, fo  as  to  produce  too  energetic  adtion  of  any  of  our 
moving  organs,  thofe  motions  foon  ceafe  though  the  ftimulus 
continues  to  acl: ;  as  in  looking  long  on  a  bright  object,  as  on  an 
inch-fquare  of  red  filk  laid  on  white  paper  in  the  funmine.  See 
Plate  I.  in  Sea.  III.  i. 

On  the  contrary,  where  lefs  of  the  ftimulus  of  volition,  fenfa- 
tion,  or  irritation,  has  been  applied  to  a  mufcle  than  ufual ; 
there  appears  to  be  an  accumulation  of  the  fpirit  of  animation  in 
the  moving  organ  ;  by  which  it  is  liable  to  acl:  with  greater 
energy  from  lefs  quantity  of  ftimulus,  than  was 'previoufly  nec- 
eflary  to  excite  it  into  fo  great  action  ;  as  after  having  been  im- 
merfed  in  fnow  the  cutaneous  veflels  of  our  hands  are  excited 

into 


SECT.  XXXVI.  2.  i.          OF  DISEASES.  353 

Into  ftronger  a£lion   by  the  ftimulus  of  a    lefs  degree  of  heat 
than  would  previoufly  have  produced  that  effect. 

From  hence  the  periods  of  fDoie  fever-fits  may  take  their  ori- 
gin, either  (imply,  or  by  their  accidental  coincidence  with  lunar 
and  folar  periods,  or  with  the  diurnal  periods  of  heat  and  cold, 
to  be  treated  of  below  5  for  during  the  cold  fit  at  the  commence- 
ment of  a  fever,  from  whatever  caufe  that  cold  fit  may  have 
been  induced,  it  follows,  i.  That  the  fpirit  of  animation  mud 
become  accumulated  in  the  parts,  which  exert  during  this  cold 
fit  lefs  than  their  natural  quantity  of  aclion.  2.  If  the  caufe 
producing  the  cold  fit  does  not  increafe,  or  becomes  diminiihed  ; 
the  parts  before  benumbed  or  inactive  become  now  excitable  by 
fmaller  ftimulus,  and  are  thence  thrown  into  more  violent  ac- 
tion than  is  natural  ;  that  is  a  hot  fit  fucceeds  the  cold  one.  3. 
By  the  energetic  aciion  of  the  fyftem  during  the  hot  fit,  if  it 
continues  long,  an  exhauftion  of  the  fpirit  of  animation  takes 
place  ;  and  another  cold  fit  is  liable  to  fucceed,  from  the  moving 
fyitem  not  being  excitable  into  action  from  its  ufual  ftimulus. 
This  inirritability  of  the  fyftem  from  a  too  great  previous  ftimu- 
lus, and  confequent  exhauftion  of  fenforial  power,  is  the  caufe  of 
the  general  debility,  and  ficknefs,  and  head-ach,  fome  hours  af- 
ter intoxication.  And  hence  we  fee  one  of  the  caufes  of  the 
periods  of  fever-fits  ;  which  however  are  frequently  combined 
with  the  periods  of  our  diurnal  habits,  or  of  heat  and  cold,  or  of 
folar  or  lunar  periods. 

When  befides  the  tendency  to  quiefcence  occafioned  by  the 
expenditure  of  fenforial  power  during  the  hot  fit  of  fever,  fome 
other  caufe  of  torpor,  as  the  folar  or  lunar  periods,  is  neceflary 
to  the  introduction  of  a  fecond  cold  fit  5  the  fever  becomes  of 
the  intermittent  kind  ;  that  is,  there  is  a  fpace  of  time  intervenes 
between  the  end  of  the  hot  fit,  and  the  commencement  of  the 
next  cold  one.  But  where  no  exterior  caufe  is  neceffary  to  the 
introduction  of  the  fecond  cold  fit  ;  no  fuch  interval  of  health 
intervenes  5  but  the  fecond  cold  fit  commences,  as  foon  as  the 
fenforial  power  is  fufEciently  exhaufted  by  the  hot  fit  ;  and  the 
fever  becomes  continual. 

II.  i.  The  following  are  natural  animal  actions,  which  are 
frequently  catenated  with  our  daily  habits  of  life,  as  well  as  ex- 
cited by  their  natural  irritations.  The  periods  of  hunger  and 
thirft  become  catenated  with  certain  portions  of  time,  or  degrees 
of  exhauftion,  or  other  diurnal  habits  of  life.  And  if  the  pain 
of  hunger  be  not-relieved  by  taking  food  at  the  ufual  time,  it  is 
liable  to  ceafe  till  the  next  period  of  time  or  other  habits  recur  ; 
this  is  not  only  true  in  refpecl  to  our  general  defire  of  food,  but 
the  kinds  of  it  alfo  are  governed  by  this  periodical  habit ;  info- 

VOL.  I.  X  x  much 


354  PERIODS  SECT,  XXXVI.  2,  2. 

much  that  beer  taken  to  breakfaft  will  difturb  the  digeflion  of 
thofe,  who  have  been  accuftomed  to  tea  ;  and  tea  taken  at  din- 
ner will  difagree  with  thofe,  who  have  been  accuftomed  to  beer. 
Whence  it  happens,  that  thofe,  who  have  weak  ftomachs,  will 
be  able  to  digeft  more  food,  if  they  take  their  meals  at  regular 
hours  ;  becaufe  they  have  both  the  ftirnulus  of  the  aliment  they 
take,  and  the  periodical  habit,  to  affift  their  digeftion. 

The  periods  of  emptying  the  bladder  are  not  only  dependent 
on  the  acrimony  or  diftention  of  the  water  in  it,  but  are  fre- 
quently catenated  with  external  cold  applied  to  the  fkin,  as  in 
cold  bathing,  or  warning  the  hands  ;  or  with  other  habits  of 
life,  as  many  are  accuftomed  to  empty  the  bladder  before  going 
to  bed,  or  into  the  houfe  after  a  journey,  and  this  whether  it  be 
full  or  not. 

Our  times  of  refpiration  are  not  only  governed  by  the  ftimu- 
lus  of  the  blood  in  the  lungs,  or  our  defire  of  frefh  air,  but  alfo 
by  our  attention  to  the  hourly  objects  before  us.  Hence  when 
a  perfon  is  earneftly  contemplating  an  idea  of  grief,  he  forgets  to 
breathe,  till  the  fenfation  in  his  lungs  becomes  very  urgent  ; 
and  then  a  figh  fucceeds  for  the  purpofe  of  more  forcibly  pufh- 
Ing  forwards  the  blood,  which  is  accumulated  in  the  lungs. 

Our  times  of  refpiration  are  alfo  frequently  governed  in  part 
by  our  want  of  a  fteady  fupport  for  the  aftions  of  our  arms, 
and  hands,  as  in  threading  a  needle,  or  hewing  wood,  or  in 
fwimming  •,  when  we  are  intent  upon  thefe  obje&s,  we  breathe 
at  the  intervals  of  the  exertion  of  the  pe£loral  mufcles. 

2.  The  following  natural  animal  actions  are  influenced  by  fo- 
lar  periods.  The  periods  of  fleep  and  of  waking  depend  much 
on  the  folar  period,  for  we  are  inclined  to  fleep  at  a  certain  hour, 
and  to  awake  at  a  certain  hour,  whether  we  have  had  more  or 
lefs  fatigue  during  the  day,  if  within  certain  limits  ;  and  are  li- 
able to  wake  at  a  certain  hour,  whether  we  went  to  bed  earlier 
or  later,within  certain  limits.  Hence  it  appears,  that  thofe  who 
complain  of  want  of  fleep,  will  be  liable  to  fleep  better  or  longer 
if  they  accuftoni  themfelves  to  go  to  reft,  and  to  rife  at  certain 
hours. 

The  periods  of  evacuating  the  bowels  are  generally  connected 
with  fome  part  of  the  folar  day,  as  well  as  with  the  acrimony  or 
diftention  occafioned  by  the  feces.  Hence  one  method  of  cor- 
re£Ung  coftivenefs  is  by  endeavouring  to  eftablifh  a  habit  of 
evacuation  at  a  certain  hour  of  the  day,  as  recommended  by  Mr. 
Locke,  which  may  be  accomplifhed  by  ufing  daily  voluntary  ef- 
forts at  thofe  times,  joined  with  the  ufual  ftimulus  of  the  mate- 
rial to  be  evacuated. 

j.  The  following  natural  animal  aftions  are  connefted  with 

lunar 


SECT.  XXXVI.  3.  i.         OF  DISEASES.  355 

lunar  periods,  i  •  The  periods  of  female  menftruation  are  con- 
nected with  lunar  periods  to  great  exaftnefs,  in  fome  inftances 
even  to  a  few  hours.  Thefe  do  not  commence  or  terminate  at 
the  full  or  change,  or  at  any  other  particular  part  of  the  luna- 
tion, but  after  they  have  commenced  at  any  part  of  it,  they  con- 
tinue to  recur  at  that  part  with  great  regularity,  unlefs  difturbed 
by  fome  violent  circumftance,  as  explained  in  Sedh  XXXII. 
No.  6.  their  return  is  immediately  caufed  by  deficient  venous 
abforption,  which  is  owing  to  the  want  of  the  ftimulus,  defigned 
by  nature,  of  amatorial  copulation,  or  of  the  growing  fetus. 
When  the  catemenia  returns  fooner  than  the  period  of  lunation, 
it  (hews  a  tendency  of  the  conftirution  to  irritability ;  that  is  to 
debility,  or  deficiency  of  fenforial  power,  and  is  to  be  relieved 
by  fmall  dofes  of  fteel  and  opium. 

The  venereal  orgafm  of  birds  and  quadrupeds  feems  to  com- 
mence, or  return  about  the  mod  powerful  lunations  at  the  ver- 
nal or  autumnal  equinoxes  ;  but  if  it  be  difappointed  of  its  ob- 
jecl,  it  is  faid  to  recur  at  monthly  periods  ;  in  this  refpecl:  re- 
fembling  the  female  catamenia.  Whence  it  is  believed,  that 
women  are  more  liable  ro  become  pregnant  at  or  about  the  rime 
of  their  catamenia,  than  at  the  intermediate  times;  and  on  this 
account  they  are  feldom  much  miltaken  in  their  reckoning  of 
nine  lunar  periods  from  the  lalt  menftruation  ;  the  attention  to 
this  may  fometimes  have  been  the  caufeof  fuppofed  barrennefs, 
and  is  Therefore  worth  the  obfervation  of  thofe,  who  wifh  to 
have  children. 

III.  We  now  come  to  the  periods  of  difeafed  animal  aftions. 
The  periods  of  fever-fits,  which  depend  on  the  Hated  returns  of 
nodlurnal  cold,  are  di  feu  fled  in  Se£l.  XXXII.  3.  Thofe  which 
originate  or  recur  at  folar  or  lunar  periods,  are  alfo  explained  in 
Section  XXXIL  6.  Thefe  we  (hall  here  enumerate  ;  obferv- 
ing,  however,  that  it  is  not  more  furprifing,  that  the  influence  of 
the  varying  attractions  of  the  fun  and  moon,  (hould  raiie  the 
ocean  into  mountains,  than  that  it  mould  afFetl:  the  nice  fenfi- 
bilities  of  animal  bodies  ;  though  the  maruier  of  its  operation  on 
them  is  difficult  to  be  underftood.  It  is  probable  however,  that 
as  this  influence  gradually  leflens  during  the  courfe  of  the  day, 
or  of  the  lunation,  or  of  the  year,  fome  actions  of  our  fyftem  be- 
come lefs  and  lefs  ;  till  at  length  a  total  quiefcence  of  fome  part 
is  induced  ;  which  is  the  commencement  of  the  paroxyfms  of 
fever,  of  menftruation,  of  pain  with  decreafed  aclion  of  the  af- 
fecled  organ,  and  of  confequent  convullion. 

i.  A  diurnal  fever  in  fome  weak  people  is  diftinftly  obferved 
to  come  on  towards  evening,  and  to  ceale  with  a  moid  (kin  early 
in  the  morning,  obeying  the  folar  periods.  Perfons  of  weak 

conftitutions 


356  PERIODS          SECT.  XXXVI.  3.  2. 

conftitutions  are  liable  to  get  into  better  fpirits  at  the  accefs  of 
the  hot  fit  of  this  evening  fever  ;  and  are  thence  inclined  to  fit 
up  late  ;  which  by  further  enfeebling  them  increases  the  dif- 
eafe  ;  whence  they  lofe  their  ftrength  and  their  colour. 

Hence  delicate  ladies,  who  do  not  ufe  rouge,  are  obferved  to 
become  paler  in  the  evening  ;  which  is  probably  owing  to  the 
circulation  through  the  whole  fyftem  being  lefs  frequently  per- 
formed in  a  given  time,  though  the  pulfe  is  quicker  ;  and  hence 
the  mafs  of  blood  becomes  lefs  frequently  oxygenated  in  the 
lungs,  and  in  confequence  has  a  lefs  florid  colour.  This  pale 
colour  therefore  arifes  from  debility,  which  occurs  to  delicate 
people  in  the  evening  from  the  exhauftion  of  fenforial  power 
during  the  day,  and  is  generally  attended  by  quicknefs  of  pulfe  ; 
by  which  circumftance  the  debility  may  in  fome  degree  be 
meafured. 

Another  caufe  of  the  colour  of  the  fkin  may  occafionally  de- 
pended on  the  increafed  aftion  of  the  cutaneous  capillaries,  as  in 
the  hot  fit  of  fever  ;  or  by  the  prod ucl  ion  of  new  blood  veflels, 
as  in  topical  inflammations  And  palenefs  may  arife  from  the 
contrary  fituations,  as  from  inaftion  of  the  cutaneous  capillaries 
in  the  cold  paroxyfm  of  fever,  and  from  the  concretion  of  the 
fides  of  the  fmall  cutaneous  arteries,  as  in  old  age. 

2  The  periods  of  hec~Hc   fever,  fuppofed  to  arife  from  ab- 
forption  of  matter,  obey  the  diurnal    periods  like  the  above, 
having  the  exacerbefcence    towards    evening,  and  the  remif- 
fion  early  in  the  morjning,   with   fweats,  or  diarrhoea,  or  urine 
with  white  fediment. 

3  The  periods  of   quotidian  fever  are  either  catenated  with 
folar  time,  and  return  at  the  intervals  of  twenty- four  hours  ;  or 
with  lunar  time,  recurring  at  the  intervals  of  about  twenty- five 
hours.     There  is  great  ufe  in  knowing  with  what  circumflances 
the  periodical  return  or  new  morbid  motions  are  conjoined,  as 
tfee  moft  effectual  times  of  exhibiting  the  proper  medicines  are 
thus  determined.     So  if  the  torpor,  which  ufliers  in  an  ague  fit, 
is  catenated  with  the  lunar  day  ;  it  is  known  when  the  bark  or 
opium  muft  be  given,  fo  as  to  exert  itvS  principal  effeft  about  the 
time  of  the  expe&ed  return.    Solid  opium  (hould  be  given  about 
an  hour  before  the    expedted  cold  fit ;  liquid  opium  and  wine 
about  half  an  hour  ;  the   bark  repeatedly  for  fix  or  eight  hours 
previous  to  the  expe&ed  return. 

4.  The  periods  of  tertian  fevers,  reckoned  from  the  com- 
mencement of  one  cold  fit  to  the  commencement  of  the  next 
cold  fit,  recur  with  folar  intervals  of  forty-eight  hours,  or  with 
lunar  ones  of  about  fifty  hours.  When  the  recurrence  of  thefe 
begins  one  or  two  hours  earlier  than  the  folar  period,  it  (hews, 

that 


SECT.  XXXVI.  3.  5.       OF  DISEASES.  357 

that  the  torpor  or  cold  fit  is  produced  by  lefs  external  influence; 
and  therefore  that  it  is  more  liable  to  degenerate  into  a  fever 
with  only  retniflions  j  fo  when  menftruation  recurs  fooner  than 
the  period  of  lunation,  it  (hews  a  tendency  of  the  habit  to  tor- 
por or  inirritability. 

5.  The  periods  of  quartan  fevers  return  at  folar  intervals  of 
feventy-two  hours,  or  at  lunar  ones  of  about  feventy-four  hours 
and  a  half.     This  kind  of  ague  appears  moft  in  moid  cold  au- 
tumns, and  in    cold   countries   replete  with  marlhes.     It  is  at- 
tended  with  greater  debility,  and  its  cold  accefs  more  difficult 
to  prevent.     For  where  there  is  previoufly  a  deficiency  of  fenfp- 
rial  power  the  conflitution  is   liable  to  run  into  greater  torpor 
from  any  further  diminution  of  it ;  two  ounces  of  bark  and  fome 
fteel  mould  be  given  on  the  day  before  the  return  of  the  cold 
paroxyfm,  and  a  pint  of  wine  by  degrees  a  few  hours  before  its 
return,  and    thirty    drops  of  laudanum  one  hour  before  the  ex* 
peeled  cold  fit. 

6.  The    periods  of  the  gout  generally  commence  about  an 
hour  before  fun-rife,   which  is  ufually  the  coldeft  part  of  the 
twenty-four  hours.     The  greater  periods  of  the  gout  feem  alfo 
to  obferve  the  folar  influence,  returning  about  the  fame  feafon 
of  the  year. 

7.  The  periods  of  the   pleurify  recur  with  exacerbation  of  the 
pain  and    fever    about   fun-fet,  at  which  time  venefeclion  is  of 
mod  fervice.     The  fame  may  be  obferved  of  the  inflammatory 
rheumatifm,  and  other  fevers  with  arterial  ftrength  which  feem 
to  obey  folar  periods  ;  and  thofe  with  debility  feem  to  obey  lu- 
nar ones. 

8  The  periods  of  fevers  with  arterial  debility  feem  to  obey 
the  lunar  day,  having  their  accefs  daily  nearly  an  hour  later  ; 
and  have  fometimes  two  acceflfes  in  a  day,  refembling  the  lunar 
effects  upon  the  tides. 

9.  The  periods  of  rhaphania,  or  convulfions  of  the  limbs  from 
rheumatic  pain,  feem  to  be  connected  with  folar  influence,  re- 
turning at  nearly  the  fame  hour  for  weeks  together,  unlefs  dif- 
turbed  by  the  exhibition  of  powerful  dofes  of  opium. 

So  the  periods  of  tuflis  ferina,  or  violent  cough  with  flow 
pulfe,  called  nervous  cough,  recur  by  folar  periods.  Five  grains 
of  opium  given  at  the  time  the  cough  commenced  difturbed  the 
period,  from  feven  in  the  evening  to  eleven,  at  which  time  it 
regularly  returned  for  fome  days,  during  which  time  the  opium 
was  gradually  omitted.  Then  120  drops  of  laudanum  were 
given  an  hour  before  the  accefs  of  the  cough,  and  it  totally 
ceafed.  The  laudanum  was  continued  a  fortnight,  and  then 
gradually  difcontinued. 

is.  The 


358  PERIODS        SECT  XXXVI.  3.  10. 

jo.  The  periods  of  hemicrania,  and  of  painful  epilepfy,  are 
liable  to  obey  lunar  periods,  both  In  their  diurnal  returns,  and 
in  their  greater  periods  of  weeks,  but  are  alfo  induced  by  other 
exciting  caufes. 

11.  The  periods  of  arterial  haemorrhages  feem  to  return  at 
folar  periods  about  the  fame  hour  of  the  evening  or  morning. 
Perhaps  the  venous  haemorrhages  obey  the  lunar  periods,  as  the 
catamema,  and  haemorrhoids. 

i  2.  The  periods  of  the  haemorrhoids,  or  piles,  in  fome  recur 
monthly,  in  others  only  at  the  greater  lunar  influence  about  the 
equinoxes. 

13.  The  periods  of  hsemoptoe  fometimes  obey  folar  influence, 
recurring  early  in  the  morning  for  feveral  days  ;  and  fometimes 
lunar  periods,  recurring  monthly  ;  and    fometimes  depend  on 
our  hours  of  fleep.     See  Clafs  I.  2.  i  9. 

14.  Many  of  the  firft  periods  of  epileptic  fits  obey  the  month- 
ly lunation  with  fome  degree  of  accuracy  ;  others  recur  only  at 
the  moft  powerful  lunations  before  the  vernal  equinox,  and  af- 
ter the  autumnal  one  ;  but  when  the  conftitution  has  gained    a 
habit  of  relieving  difagreeable  fenfations  by  this  kind  of  exertion 
the  fit  recurs  from  any  flight  caufe. 

15.  The  attack  of  palfy  and  apoplexy  are  known  to  recur  with 
great  frequency  about  the  equinoxes. 

1 6.  There  are  numerous  inflances  of  the  effect  of  the  luna- 
tions upon  the  periods  of  infanity,  whence  the  name  of  lunatic 
has  been  given  to  thofe  afflicted  with  this  difeafe. 

IV.  The  critical  days,  in  which  fevers  are  fuppofed  to  termi- 
nate, have  employed  the  attention  of  medical  philofophers  from 
the  days  of  Hippocrates  to  the  prefent  time.  In  whatever  part 
of  a  lunation  a  fever  commences,  which  owes  either  its  whole 
caufe  to  folar  and  lunar  influence,  or  to  this  in  conjunction  with 
other  caufes  ;  it  would  feem,  that  the  effect  would  be  the  great- 
eft  at  the  full  and  new  moon,  as  the  tides  rife  higheft  at  thofe 
times,  and  would  be  the  lead  at  the  quadratures  -,  thus  if  a  fe- 
ver-fit mould  commence  at  the  new  or  full  moon,  occafioned 
by  the  folar  and  lunar  attraction  diminifhing  fome  chemical  af- 
finity of  the  particles  of  blood,  and  thence  decreafmg  their  Ulmu- 
lus  on  our  fanguiferous  fyftem,  as  mentioned  in  Sea.  XXXIL 
6.  this  effect  will  daily  decreafe  for  the  firft  feven  days,  and 
will  then  increafe  till  about  the  fourteenth  day,  and  will  ugain 
decreafe  till  about  the  twenty-firft  day,  and  increafe  again  till 
the  end  of  the  lunation.  If  a  fever  fit  from  the  above  caufe 
fhould  commence  on  the  feventh  day  after  either  lunation,  the 
reverfeof  the  above  circumstances  would  happen.  Now  it  is 
probable,  that  thofe  fevers,  whofe  crifis  or  termination  are  in- 
fluenced 


SECT.  XXXVI.  4-  i-    OF  DISEASES.  359 

fluenced  by  lunations,  may  begin  at  one  or"other  of  the  above 
times,  namely  at  the  changes  or  quadratures  ;  though  fufficient 
obfervations  have  not  been  made  to  afcertain  this  rircumftance. 
Hence  I  conclude,  that  the  fmall-pox  and  meafie?  have  their 
critical  days,  not  governed  by  the  times  required  for  certain 
chemical  changes  in  the  blood,  which  affect  or  alter  the  ftimu- 
lus  of  the  contagious  matter,  but  from  the  daily  increafing  or 
decreafing  effect  of  this  lunar  link  of  catenation,  as  explained  in 
Se6lion  XVII.  3.  3.  And  as  other  fevers  terminate  moft  fre- 
quently about  the  feventh,  fourteenth,  twenty- firft,  or  about  the 
end  of  four  weeks,  when  no  medical  affiftance  has  difturbed 
their  periods,  I  conclude,  that  thefe  crifes,  or  terminations,  are 
governed  by  periods  of  the  lunations,  though  we  are  (till  igno- 
rant of  their  manner  of  operation. 

In  the  diftincl  fmall-pox  the  veiliges  of  lunation  are  very  ap- 
parent ;  after  inoculation  a  quarter  of  a  lunation  precedes  the 
commencement  of  the  fever,  another  quarter  terminates  with 
the  complete  eruption,  another  quarter  with  the  complete  matu- 
ration, and  another  quarter  terminates  the  complete  abforption 
of  a  material  now  rendered  inoffenfive  to  the  confthution. 


SECT. 


36o  DIGESTION,        SECT.  XXXVII.  i.  i. 

SECT.      XXXVIL 

OF  DIGESTION,     SECRETION,  NUTRITION. 

I.  Cryjlals  tncreafe  by  the  greater  attraclion  of  their  Jides.  Accre- 
tion by  chemical  precipitations,  by  welding^  by  preflure,  by  aggluti- 
nation. II  Hunger ',  digejlion^  why  it  cannot  be  imitated  out  of 
the  body.  Lacleals  abforb  by  animal  feleclion^  or  appetency.  III. 
The  glands  and  pores  abforb  nutritious  particles  by  animal felecHon. 
Organic  particles  of  Buff  on.  Nutrition  applied  at  the  time  of 
elongation  of  fibres.  Like  inflammation.  IV.  It  feems  eafier  to 
have  preferred  animals  than  to  reproduce  them.  Old  age  and  death 
from  inirrit  ability*  Three  cau/es  of  this.  Original  fibres  of  the 
organs  of  fenfe  and  mufcles  unchanged.  V.  Art  of  producing 
long  life. 

I.  THE  larger  cryftals  of  faline  bodies  may  be  conceived  to 
arife  from  the  combination  of  fmaller  cryftals  of  the  fame  form, 
owing  to  the  greater  attractions  of  their  fides  than  of  their  an- 
gles. Thus  if  eight  cubes  were  floating  in  a  fluid,  whofe  fric- 
tion or  refiftance  is  nothing,  it  is  certain  the  fides  of  thefe  cubes 
would  attract  each  other  ftronger  than  their  angles  ;  and  hence 
that  thefe  eight  fmaller  cubes  would  fo  arrange  themfelves  as  to 
produce  one  larger  one. 

There  are  other  means  of  chemical  accretion,  fuch  as  the  de» 
pofitions  of  diflblved  calcareous  or  filiceous  particles,  as  are  feen 
in  the  formation  of  the  ftalaCtites  of  limeftone  in  Derbyfhire,  or 
of  calcedorie  in  Cornwall  Other  means  of  adhefion  are  produ- 
ced by  heat  and  preflure,  as  in  the  welding  of  iron-bars  ;  and 
other  means  by  fimple  preflure,  as  in  forcing  two  piece  of  ca- 
outchou,  or  elaftic  gum,  to  adhere  ;  and  laftly,  by  the  aggluti- 
nation of  a  third  fubftance  penetrating  the  pores  of  the  other 
two,  as  in  the  agglutination  of  wood  by  means  of  animal  gluten. 
Though  the  ultimate  particles  of  animal  bodies  are  held  togeth- 
er during  life,  as  well  as  after  death,  by  their  fpecific  attraction 
of  cohefion,  like  all  other  matter  j  yet  it  does  not  appear,  that 
their  original  organization  was  produced  by  chemical  laws,  and 
their  production  and  increafe  muft  therefore  only  be  looked  for 
from  the  laws  of  animation. 

II.  When  the  pairr  of  hunger  requires  relief,  certain  parts  of 
the  material  world,  which  furround  us,  when  applied  to  our 
palates,  excite  into  a£Uon  the  mufcles  of  deglutition  ;  and  the 
material  is  fwallowed  into  the  ftomach.  Here  the  new  aliment 
becomes  mixed  with  certain  animal  fluids,  and  undergoes  a 

chemical 


SECT.  XXXVII.  3.  i.      SECRETION,  &c.  36: 

chemical  procefs,  termed  digeftion  ;  which,  however,  chemiftry 
has  not  yet  learnt  to  imitate  out  of  the  bodies  of  living  animate 
or  vegetables.  This  procefs  feems  very  fimiiar  to  the  faccharine 
procefs  in  the  lobes  of  farinaceous  feeds,  as  of  barley,  when  it 
begins  to  germinate  ;  except  that,  along  v/ith  the  fugar,  oil  and 
mucilage  are  aiio  produced  •,  which  form  the  chyle  of  animals, 
which  is  very  fimilar  to  their  milk. 

The  reafon,  I  imagine,  why  this  chyle-making,  or  faccharine 
procefs,  has  not  yet  been  imitated  by  chemical  operations,  is 
owing  to  the  materials  being  in  fuch  a  fituation  in  refpedl  to 
warmth,  moiilure,  and  motion  ;  that  they  will  immediately 
change  into  the  vinous  or  acetous  fermentation  ;  except  the 
new  fugar  be  abforbed  by  the  numerous  lacleal  or  lymphatic 
veflels,  as  foon  as  it  is  produced  j  which  is  not  cafy  to  imitate 
in  the  laboratory. 

Thefe  lacteal  vefTels  have  mouths,  which  are  irritated  into  ac- 
tion by  the  ftimulus  of  the  fluid  which  furrounds  them  ;  and  by 
animal  fe!e£Hon,  or  appetency,  they  abforb  fuch  part  of  the  flu- 
id as  is  agreeable  to  their  palate  ;  tho  e  parts,  for  inftance, 
which  are  already  converted  into  chyle,  before  they  have  time 
to  undergo  another  change  by  a  vinous  or  acetous  fermentation. 
This  animal  abforption  of  fluid  is  almoft  vifible  to  the  naked  eye 
in  the  aftion  of  the  pun: la  lachrymalia  ;  which  imbibe  the  tears 
from  the  eye,  and  difcharge  them  again  into  the  noftrils. 

III.  The  arteries  coniiitute  another  refervoir  of  a  changeful 
fluid  ;  from  which,  after  its  recent  oxygenation  in  the  lungs,  a 
further  animal  feledlion  of  various  fluids  is  abforbed  by  the  nu- 
merous glands  •,  thefe  fele£l  their  refpe&ive  fluids  from  the 
blood,  which- is  perpetually  undergoing  a  chemical  change  ;  but 
the  feledlion  by  thefe  glands,  like  that  of  the  lacleals,  which 
open  their  mouths  into  the  digefling  aliment  in  the  ftomach,  is 
from  animal  appetency,  not  from  chemical  affinity  ;  fecretion 
cannot  therefore  be  imitated  in  the  laboratory,  as  it  confifts  in  a 
fele&ion  of  part  of  a  fluid  during  the  chemical  change  of  that 
fluid. 

The  mouths  of  the  lafteals,  and  lymphatics,  and  the  ultimate 
terminations  of  the  glands,  are  finer  than  can  eafily  be  conceived  ; 
yet  it  is  probable,  that  the  pores,  or  interfaces  of  the  parts,  or 
coats,  which  conftitute  thefe  ultimate  veflels,  may  ftill  have 
greater  tenuity  ;  and  that  thefe  pores  from  the  above  analogy 
mull  poflefs  a  fimilar  power  of  irritability,  and  abforb  by  their 
living  energy  the  particles  of  fluid  adapted  to  their  purpofes, 
whether  to  replace  the  parts  abraded  or  diflblved,  or  to  elongate 
and  enlarge  themfelves,  Not  only  every  kind  of  gland  is  thus 
endued  with  its  peculiar  appetency,  and  feledts  the  material 
VOL.  I.  Y  Y  agreeable 


362  DIGESTION,        SECT.  XXXVII.  3.  i. 

agreeable  to  its  tafte  from  the  blood,  but  every  individual  pore 
acquires  by  animal  fele^ion  the  material,  which  it  wants  ;  and 
thus  nutrition  feems  to  be  performed  in  a  manner  fo  fimilar  to 
fecretion  ;  that  they  only  differ  in  the  one  retaining,  and  the 
other  parting  again  with  the  particles,  which  they  have  fele£led 
from  the  blood. 

They  may,  indeed,  differ  in  another  circum fiance  ;  that  in 
nutrition  certain  particles  of  the  circulating  blood,  which  have 
not  prevfoufly  been  ufed  in  the  fyflem,  are  embraced,  and  form 
a  folid  part  of  the  animal.  Whereas  in  fome  of  the  fecretions, 
thofe  particles  appear  to  be  imbibed  by  the  glands,  which  have 
already  been  ufed  in  the  fyftem,  and  probably  abraded  or  de- 
tached from  it  into  the  circulation  :  thefe  are  depoGted  in  refer- 
voirs  for  future  ufe,  as  bile  and  mucus ;  or  excluded  for  other 
purpofes,  as  femen  and  tears  ;  or  evacuated  fimply  as  feces  and 
urine.  And  it  fhould  be  obferved,  that  all  the  fecretions  are 
produced  from  their  glands,  in  a  very  dilute  date,  mingled,  I  be- 
lieve, with  mucus  diflblved  in  water  :  which  is  in  part  re-ab- 
forbed  from  the  refervoirs  of  the  glands,  or  from  the  cells  or 
furfaces  of  the  body,  that  no  unneceflary  wafte  of  animal  mat- 
ter may  occur  ;  which  accounts  for  the  urinary  bladders  of  fifh, 
which  would  otherwife  appear  to  be  unneceflary,  according  to 
the  obfervation  of  Munro. 

This  way  of  accounting  for  nutrition  from  ftimulus,  and  the 
confequent  animal  fele&ion  of  particles,  is  much  more  analo- 
gous to  other  phenomena  of  the  animal  microcofm,  than  by 
having  recourfe  to  the  microfcopic  animalcula,  or  organic  par- 
ticles of  Buffbn  and  Needham  ;  which  being  already  compound- 
ed mud  themfelves  require  nutritive  particles  to  continue  their 
own  exiftence.  And  muft  be  liable  to  undergo  a  change  by  our  di- 
geftive  or  fecretory  organs;  otherwife  mankind  would  foon  refem- 
ble  by  their  theory  the  animals  which  they  feed  upon.  He,  who 
is  nourifhed  by  beef  or  venifon,  would  in  time  become  horned  ; 
and  he,  who  feeds  on  pork  or  baeon,  would  gain  a  nofe  proper 
for  rooting  into  the  earth,  as  well  as  for  the  perception  of  odours. 

The  whole  animal  fyftem  may  be  conlidered  as  confiding  of 
the  extremities  of  the  nerves,  or  of  having  been  produced  from 
them  ;  if  we  except  perhaps  the  medullary  part  of  the  brain 
refiding  in  the  head  and  fpine,  and  in  the  trunks  of  the  nerves. 
Thefe  extremities  of  the  nerves  are  either  of  thofe  of  locomotion, 
which  are  termed  mufcular  fibres  ;  or  of  thofe  of  fenfation, 
which  conftitute  the  immediate  organs  of  fenfe,  and  which  have 
alfo  their  peculiar  motions.  Now  as  the  fibres,  which  confti- 
tute the  bones  and  membranes,  poflefled  originally  fenfation  and 
motion  ;  and  are  liable  again  to  poflefs  them,  when  they  become 

inflamed ; 


SECT.  XXXVII.  3.  i.      SECRETION,  &c.  363 

inflamed  ;  it  follows,  that  thole  were,  when  firft  formed,  ap- 
pendages to  the  nerves  of  fenfation  or  locomotion,  or  were 
formed  from  them.  And  that  hence  all  thefe  folid  parts  of  the 
body,  as  they  have  originally  confided  of  extremities  of  nerves, 
require  an  appofition  of  nutritive  particles  of  a  fimilar  kind, 
contrary  to  the  opinion  of  BufTon  and  Needham  above  recited. 

Laftly,  as  all  thefe  filaments  have  poflefled,  or  do  poflefs,  the 
power  of  contraction,  and  of  confequent  inertion  or  elongation  ; 
it  feems  probable,  that  the  nutritive  particles  are  applied  during 
their  times  of  elongation  ;  when  their  original  condiment  par- 
ticles are  removed  to  a  greater  diftance  from  each  other.  For 
each  mufcular  or  fenfual  fibre  may  be  confidered  as  a  row  or 
firing  of  beads  ;  which  approach,  when  in  contraction,  and  re- 
cede during  its  reft  or  elongation  \  and  our  daily  experience 
{hews  us,  that  great  action  emaciates  the  fydem,  and  that  it  is 
repaired  during  reft. 

Something  like  this  is  feen  out  of  the  body  ;  for  if  a  hair,  or 
a  fingle  untwided  fibre  of  flax  or  filk,  be  foaked  in  water  ;  it  be- 
comes longer  and  thicker  by  the  water,  which  is  abforbed  into. 
its  pores.  Now  if  a  hair  could  be  fuppofed  to  be  thus  rmmerfed. 
in  a  folution  of  particles  fimilar  to  thofe,  which  compofe  it  ; 
one  may  imagine,  that  it  might  be  thus  increafed  in  weight  and 
magnitude ;  as  the  particles  of  oak-bark  increafe  the  fubdance 
of  the  hides  of  beads  in  the  procefs  of  making  leather.  I  men- 
tion thefe  not  as  philofophic  analogies,  but  as  fimilies  to  facili- 
tate our  ideas,  how  an  accretion  of  parts  may  be  effected  by 
animal  appetences,  or  feleclions,  in  a  manner  fomewhat  fimilar 
to  mechanical  or  chemical  attractions. 

If  thole  new  particles  of  matter,  previoufly  prepared  by  di- 
geftion  and  fanguification,  only  fupply  the  places  of  thofe,  which 
have  been  abraded  by  the  actions  of  the  fydem,  it  is  properly* 
termed  nutrition.  If  they  are  applied  to  the  extremities  of  the 
nervous  fibrils,  or  in  fuch  quantity  as  to  increafe  the  length  or 
crafhtude  of  them,  the  body  becomes  at  the  fame  time  enlarged, 
and  its  growth  is  increafed,  as  well  as  its  deficiencies  repaired, 

In  this  lad  cafe  fomething  more  than  a  fimple  appofition  or 
felection  of  particles  feems  to  be  neceflary  ;  as  many  parts  of 
the  fydem  during  its  growth  are  caufed  to  recede  from  thofe, 
with  which  they  were  before  in  contact ;  as  the  ends  of  the 
bones,  or  cartilages,  recede  from  each  other,  as  their  growth 
advances :  this  procefs  refembles  inflammation,  as  appears  in 
ophthalmy,  or  in  the  production  of  new  flefh  in  ulcers,  where 
old  veffcls  are  enlarged,  and  new  ones  produced  ;  and  like  that 
is  attended  with  fenfation.  In  this  fituation  the  veflels  become 
didended  with  blood,  and  acquire  greater  fenfibility,  and  may 

thus 


364  DIGESTION,        SECT.  XXXVII.  4.  i . 

s 

thus  be  compared  to  the  eredion  of  the  penis,  or  of  the  nipples 
of  the  breafts  of  women  ;  while  new  particles  become  added  at 
the  fame  time  ;  as  in  the  procefs  of  nutrition  above  defcribed. 

When  only  the  natural  growth  of  the  various  parts  of  the 
body  is  produced,  a  pleafurable  fenfation  attends  it,  as  in  youth, 
and  perhaps  in  thofe,  who  are  in  the  progrefs  of  becoming  fat. 
When  an  unnatural  growth  is  the  confequence,  as  in  inflam- 
matory difeafes,  a  painful  fenfation  attends  the  enlargement  of 
the  fyftem. 

IV.  This  appofition  of  new"  parts,  as  the  old  ones  difappear, 
felefted  from  the  aliment  we  take,  firft  enlarges  and  ftrength- 
ens  our  bodies  for  twenty  years ;  for  another  twenty  years  it 
keeps  us  in  health  and  vigour,  and  adds  ilrength  and  folidity  to 
the  fyftem,  and  then  gradually  ceafes  to  nourifh  us  properly  ; 
and  for  another  twenty  years  we  gradually  fink  into  decay,  and 
finally  ceafe  to  acl,  and  to  exift. 

On  confidering  this  fubjetl  one  fhould  have  imagined  at  firft 
view,  that  it  might  have  been  eafier  for  nature  to  have  fup- 
ported  her  progeny  for  ever  in  health  and  life,  than  to  have  per- 
perually  reproduced  them  by  the  wonderful  and  myfterious 
procefs  of  generation.  But  it  feems  our  bodies  by  long  habit 
ceafe  to  obey  the  ftimulus  of  the  aliment,  which  fhould  fupport 
us.  After  we  have  acquired  our  height  and  folidity  we  make 
no  more  new  parts,  and  the  fyftem  obeys  the  irritations,  fenfa- 
tions,  volitions,  and  aflbciations,  with  lefs  and  lefs  energy,  till 
the  whole  finks  into  inaction. 

Three  caules  may  confpire  to  render  our  nerves  lefs  excitable, 
which  have  been  already  mentioned,  i .  If  a  ftimulus  be  greater 
than  natural,  it  produces  too  great  an  exertion  of  the  ftimulated 
organ,  and  in  confequence  exhaufts  the  fpirit  of  animation  ;  and 
the  moving  organ  ceafes  to  act,  even  though  the  ftiniulus  be 
continued.  And  though  reft  will  recruit  this  exhauftion,  yet 
fome  degree  of  permanent  injury  remains,  as  is  evident  after  ex- 
pofing  the  eyes  long  to  too  ftrong  a  light.  2.  If  excitations 
weaker  than  natural  be  applied,  fo  as  not  to  excite  the  organ 
into  atlion,  (as  when  fmall  dofes  of  aloes  or  rhubarb  are  ex- 
hibited,) they  may  be  gradually  increafed,  without  exciting  the 
organ  into  adion  ;  which  will  thus  acquire  a  habit  of  difobe- 
dience  to  the  ftimulus  ;  thus  by  increafing  the  dofe  by  degrees, 
great  quantities  of  opium  or  wine  may  be  taken  without  intoxi- 
cation. See  Seel.  XII.  3.  i 

3.  Another  mode,  by  which  life  is  gradually  undermined,  is 
when  irritative  motions  continue  to  be  produced  in  confequence 
of  ftimulus,  but  are  not  fucceeded  by  fenfation  ;  hence  the 
ftimulus  of  contagious  matter  is  not  capable  of  producing  fever 


SECT.  XXXVIL  5.  i.      SECRETION,  &c.  365 

a  fecond  time,  becaufe  it  is  not  fucceeded  by  fenfation.  See 
Sect.  XIL  3  6.  And  hence,  owing  to  the  want  of  the  gener- 
al pleafurable  fenfation,  which  ought  to  attend  digeftion  and 
glandular  fecretion,  an  irkfomenefs  of  life  enfues  *,  and,  where 
this  is  in  greater  excefs,  the  melancholy  of  old  age  occurs,  with 
torpor  or  debility. 

From  hence  I  conclude,  that  it  is  probable  that  the  fibrillx, 
or  moving  filaments  at  the  extremities  of  the  nerves  of  fenfe,  and 
the  fibres  which  conftitute  the  mufcles  (which  are  perhaps  the 
only  parts  of  the  fyftem  that  are'  endued  with  contraftile  life) 
are  not  changed,  as  we  advance  in  years,  like  the  other  parts  of 
the  body  ;  but  only  enlarged  or  elongated  with  our  growth  ; 
and  in  confequence  they  become  Jefs  and  lefs  excitable  into  ac- 
tion. Whence,  inftead  of  gradually  changing  the  old  animal, 
the  generation  of  a  totally  new  one  becomes  neceflary  with  un- 
diminifhed  excitability  \  which  many  years  will  continue  to  ac- 
quire new  parts,  or  new  folidity,  and  then  lofing  its  excitability 
in  time,  perifh  like  its  parent. 

V.  From  this  idea  the  art  of  preferving  long  health  and  life 
may  be  deduced  ;  which  mud  confift  in  ufmg  no  greater  ftimu- 
lus,  whether  of  the  quantity  or  kind  of  our  food  and  drink,  or 
of  external  circumftances,  fuch  as  heat,  and  exercife,  and  wake- 
fulnefs,  than  isfufficient  to  preferve  us  in  vigour  ;  and  gradual- 
ly, as  we  grow  old  to  increafe  the  ftimulus  of  our  aliment,  as 
the  inirritability  of  our  fyftem  increafes. 

The  debilitating  effeds  afcribed  by  the  poet  Martial  to  the 
exceflive  ufe  of  warm  bathing  in  Italy,  may  with  equal  propriety 
be  applied  to  the  warm  rooms  of  England  ;  which,  with  the 
general  exceflive  ftimulus  of  fpirituous  or  fermented  liquors, 
and  in  fome  inftances  of  immoderate  venery,  contribute  to 
{horten  our  lives. 

Balnea,  vina^  Venus^  corrumpant  corpora  noftra  : 
At  faclunt  vitam  balnea^  i)ina^  Venus  ! 


Wine,  women,  warmth,  againft  our  lives  combine; 
But  what  is  life,  without  warmth,  women,  wine! 


SECT. 


366  OXYGENATION    SECT.  XXXVIII.  i. 


SECT.      XXXVIIL 

OF   THE   OXYGENATION   OF   THE   BLOOD   IN    THE    LUNGSj     AND 
IN    THE    PLACENTA. 

I.  Blood  abforbs  oxygene  from  the  air ^  whence  phofphoric  acid^changes 
its  colour,  gives  out  heat^  andfome  phlogiflic  material,  and  acquires 
an  ethereal  fpirit,  which  is  diffipated  in  fibrous  motion.  II.  The 
placenta  is  a  pulmonary  organ  like  the  gills  offifh.  Oxygenation  of 
the  blood  from  air ,  from  water ,  by  lungs ,  by  gills  >  by  the  placenta  ; 
tiectffity  of  this  oxygen ation  to  quadrupeds,  to  fi/hy  to  the  fetus  in 
utero.  Placenta]  veffe/s  inferted  into  the  arteries  of  the  mother. 
Ufe  of  cotyledons  in  cows.  Why  quadrupeds  have  not  fanguifer- 
ens  lochia,  Oxygenation  of  the  chick  in  the  egg,  of  feeds.  III. 
The  liquor  amnii  is  not  excrementitious.  It  is  nutritious.  It  is 
found  in  the  e/bphagus  and  Jlomach,  and  forms  the  meconium. 
Monjlrous  births  without  heads,  ^ueflion  of  Dr.  Harvey* 

I  FROM  the  recent  difcoveries  of  many  ingenious  philofo- 
phers  it  appears,  that  during  refpiration  the  blood  imbibes  the 
vital  part  of  the  air,  called  oxygene,  through  the  membranes  of 
the  lungs ;  and  that  hence  refpiration  may  be  aptly  compared  to 
a  flow  combuftion.  As  in  combuftion  the  oxygene  of  the  at- 
mofphere  unites  with  fome  phlogiftic  or  inflammable  body,  and 
forms  an  acid,  as  in  the  production  of  vitriolic  acid  from  fulphur, 
or  carbonic  acid  from  charcoal,  giving  out  at  the  fame  time  a 
quantity  of  the  matter  of  heat ;  fo  in  refpiration  the  oxygene  of 
the  air  unites  with  the  phlogiftic  part  of  the  blood,  and  proba- 
bly produces  phofphoric  or  animal  acid,  changing  the  colour  of 
the  blood  from  a  dark  to  a  bright  red  ;  and  probably  fome  of  the 
matter  of  heat  is  at  the  fame  time  given  out  according  to  the 
theory  of  Dr.  Crawford.  But  as  the  evolution  of  heat  attends 
almoft  all  chemical  combinations,  it  is  probable,  that  it  alfo  at- 
tends the  fecretions  of  the  various  fluids  from  the  blood  ;  and 
that  the  conftant  combinations  or  productions  of  new  fluids  by- 
means  of  the  glands  conftitute  the  more  general  fource  of  ani- 
mal heat  ;  this  feems  evinced  by  the  univerfal  evolution  of  the 
matter  of  heat  in  the  blufh  of  fhame  or  of  anger  ;  in  which  at 
the  fame  time  an  increafed  fecretion  of  the  perfpirable  matter 
occurs  ;  and  the  partial  evolution  of  it  from  topical  inflamma- 
tions, as  in  gout  or  rheumatifm,  in  which  there  is  a  fecretion  of 
new  blood-veflels. 

Some  medical  philofophers  have  afcribed  the  heat  of  animal 
bodies  to  the  friftion  of  the  particles  of  the  blood  againft  the 

fides 


SECT.  XXXVIII.  2.  i.          OF  BLOOD.  367 

fides  of  the  veflels.  But  no  perceptible  heat  has  ever  been  pro- 
duced by  the  agitation  of  water,  or  oil,  or  quickfilver,  or  other 
fluids  ;  except  thofe  fluids  have  undergone  at  the  fame  time  fome 
chemical  change,  as  in  agitating  milk  or  wine,  till  they  become 
four. 

Befides  the  fuppofed  production  of  phofphoric  acid,  and 
change  of  colour  of  the  blood,  and  the  production  of  carbonic 
acid,  there  would  appear  to  be  fomething  of  a  more  fubtile  na- 
ture perpetually  acquired  from  the  atmofphere;  which  is  too 
fine  to  be  long  contained  in  animal  veflels,  and  therefore  re- 
quires perpetual  renovation  ;  and  without  which  perfect  life 
cannot  continue  longer  than  a  minute  or  two ;  this  ethereal  flu- 
id is  probably  fecreted  from  the  blood  by  the  brain,  and  perpetu- 
ally diflipated  in  the  actions  of  the  mufcles  and  organs  of  fenfe, 
but  which  neverthelefs  may  remain  for  a  longer  time,  where 
there  is  little  or  no  exertion  of  the  animated  fibres,  as  in  fyncope, 
and  in  thofe  in  feels  and  other  animals,  which  remain  during  the 
winter  in  a  torpid  (late,  and  may  not  entirely  evaporate  from, 
defect  of  warmth,  or  moifture,  or  other  circumftances,  as  fnails 
are  faid  to  have  revived  after  having  been  many  years  in  a  dry 
cabinet,  and  flies  after  having  been  many  months  drowned  in 
wine,  and  other  infects  after  having  been  frozen. 

That  the  blood  acquires  fomething  from  the  air,  which  is  im- 
mediately neceflary  to  life,  appears  from  an  experiment  of  Dr.  > 
Hare,  (Philof.  Tranfacl.  abridged,  Vol.  III.  p.  239.)  who 
found,  "  that  birds,  mice,  &c  would  live  as  long  again  in  a 
veflel,  where  he  had  crowded  in  double  the  quantity  of  air  by  a 
condenfing  engine,  than  they  did  when  confined  in  air  of  the 
common  denfity."  Whereas  if  fome  kind  of  deleterious  vapour 
only  was  exhaled  from  the  blood  in  refpiration  ;  the  air,  when 
condenfed  into  half  its  compafs,  couid  not  be  fuppofed  to  re- 
ceive fo  much  of  it. 

II.  Sir  Edward  Hulfe,  a  phyfician  of  reputation  at  the  begin- 
ning of  the  prefent  century,  was  of  opinion,  that  the  placenta 
was  a  refpiratory  organ,  like  the  gills  of  fifh  ;  and  not  an  organ 
to  fupply  nutriment  to  the  foetus  ;  as  mentioned  in  Derham's 
Phyfico-theology.  Many  other  phyficians  feem  to  have  efpoufed 
the  fame  opinion,  as  noticed  by  Haller.  Elem.  Phyfiologix,  T. 
I.  Dr.  Gipfon  publifhed  a  defence  of  this  theory  in  the  Medi- 
cal Eflays  of  Edinburgh,  Vol.  I.  and  II.  which  doctrine  is 
there  controverted  at  large  by  the  late  Alexander  Monro  j  and 
fince  that  time  the  general  opinion  has  been,  that  the  placenta 
is  an  organ  of  nutrition  only,  owing  perhaps  rather  to  the  au- 
thority of  fo  great  a  name,  than  to  the  validity  of  the  arguments 
adduced  in  its  fupport.  The  fubject  has  lately  been  refumed  by 
^  Dr. 


368  OXYGEN ATION    SECT.  XXXVIII.  2.  i 

Dr.  James  JefFray,  and  by  Dr.  Forefter  French,  in  their  inaugu- 
ral diiTertations  at  Edinburgh  and  at  Cambridge  ;  who  have  de- 
fended the  contrary  opinion  in  an  able  and  ingenious  manner  ; 
and  from  whofe  Thefes  I  have  extracted  many  of  the  following 
remarks. 

Firit,  by  the  late  difcoveries  of  Dr.  Priedley,  M.  Lavoifier, 
and  ether  philofophers,  it  appears,  thar  the  bafis  of  atmofpher- 
ical  air,  called  oxygene,  is  received  by  the  blood  through  the 
membranes  of  the  lungs  ;  and  that  by  this  addition  the  colour 
of  the  blood  is  changed  from  a  dark  to  a  light  red.  Secondly, 
that  water  poflefles  oxygene  alfo  as  a  part  of  its  compofition, 
and  contains  air  like  wife  in  its  pores  ;  whence  the  blood  of  fifh 
receives  oxygene  from  the  water,  or  from  the  air  it  contains,  by 
means  of  their  gills,  in  the  lame  manner  as  the  blood  is  oxygena- 
ted in  the  lungs  of  air-breathing  animals  ;  it  changes  its  colour 
at  the  fame  time  from  a  dark  to  a  light  red  in  the  veiTds  of  their 
gills,  which  conftitute  a  pulmonary  organ  adapted  to  the  medi- 
um in  which  they  live.  Thirdly,  that  the  placenta  confiils  of 
arteries  carrying  the  blood  to  its  extremities,  and  a  vein  bringing 
it  back,  refembling  exactly  in  ftrudlure  the  lungs  and  gills  above 
mentioned  •,  and  that  the  blood  changes  its  colour  from  a  dark 
to  a  light  red  in  paiTing  through  thefe  veflels. 

This  analogy  between  the  lungs  and  gills  of  animals,  and  the 
placenta  of  the  fetus,  extends  through  a  great  variety  of  other 
circumftances  ;  thus  air-breathing  creatures  and  fiih  can  live 
but  a  few  minutes  without  air  or  water  ;  or  when  they  are  con- 
fired  in  fuch  air  or  water,  as  has  been  fpoiled  by  their  own 
relpiration ;  the  fame  happens  to  the  fetus,  which,  as  foon  as 
the  placenta  is  feparated  from  the  uterus,  mud  either  expandjts 
lungs,  and  receive  air,  or  die.  Hence  from  the  ftruciure,  as 
well  as  the  ufe  of  the  placenta,  it  appears  to  be  a  refpiratory  or- 
gan, like  the  gills  of  fiih,  by  which  the  blood  in  the  fetus  be- 
comes oxygenated. 

From  the  terminations  of  the  placental  veflels  not  being  ob- 
ferved  to  bleed  after  being  torn  from  the  uterus,  while  thofe  of 
the  uteras  effufe  a  great  quantity  of  florid  arterial  blood,  the 
terminations  of  the  placental  veflels  would  feem  to  be  inft-rtecl 
into  the  arterial  ones  of  the  mother ;  and  to  receive  oxygenation 
from  the  pafling  currents  of  her  blood  through  their  coats  or 
membranes  ;  which  oxygenation  is  proved  by  the  change  of  the 
colour  of  the  blood  from  dark  to  light  red  in  its  paflage  from 
the  placental  arteries  to  the  placental  vein. 

The  curious  ftruciure  of  the  cavities  or  lacunae  of  the  placen- 
ta, demonftrated  by  Mr.  J  Hurrer,  explains  this  circumftance. 
This  ingenious  philofopher  has  (hewn,  that  there  are  numerous 

cavities 


SECT.  XXXVIII.  2.  i.         OF  BLOOD,  36? 

cavities  or  lacunae  formed  on  that  fide  of  the  placenta,  which  is 
in  contaft  with  the  uterus  ;  thofe  cavities  or  cells  are  filled  with 
blood  from  the  maternal  arteries,  which  open  into  them  ;  which 
blood  is  again  taken  up  by  the  maternal  veins,  and  is  thus  per- 
petually changed.  While  the  terminations  of  the  placental  ar- 
teries and  veins  are  fpread  in  fine  reticulation  on  the  fides  of 
thefe  cells.  And  thus,  as  the  growing  fejrus  requires  greater 
oxygenation,  an  apparatus  is  produced  refembling  exactly  the 
air-cells  of  the  lungs. 

In  cows,  and  other  ruminating  animals,  the  internal  fur  face 
of  the  uterus  is  unequal  like  hollow  cups,  which  have  been 
called  cotyledons  ;  and  into  thefe  cavities  the  prominences  of 
the  numerous  placentas,  with  which  the  fetus  of  thofe  aninnals 
is  furnifhed,  are  inferred,  and  ftriclly  adhere  ;  though  they  may 
be  extracted  without  effufion  of  blood  Thefe  inequalities  of 
the  uterus,  and  the  numerous  placentas  in  confequence,  feem  to 
be  defigned  for  the  purpofe  of  expanding  a  greater  furface  for 
the  terminations  of  the  placental  veflels  for  the  purpofe  of  re- 
ceiving oxygenation  from  rhe  uterine  ones  ;  as  the  progeny  of 
this  clafs  of  animals  are  more  completely  formed  before  their 
nativity,  than  that  of  the  carnivorous  clafles,  and  mud  thence  in 
the  latter  weeks  of  pregnancy  require  greater  oxygenation. 
Thus  calves  and  lambs  can  walk  about  in  a  few  minutes  after 
their  birth  ;  while  puppies  and  kittens  remain  many  days  with- 
out opening  their  eyes.  And  though  on  the  feparation  of  the 
cotyledons  of  ruminating  animals  no  blood  is  efFufed,  yet  this  is 
owing  clearly  to  the  greater  power  of  contraction  of  their  ute- 
rine lacunx  or  alveoli.  See  Medical  Eflays,  Vol  V,  page  144- 
And  from  the  fame  caufe  they  are  not  liable  to  a  fanguiferous 
menftruation. 

The  necefllty  of  the  oxygenation  of  the  blood  in  the  fetus  is 
farther  illuftrated  by  the  analogy  of  the  chick  in  the  egg  ;  which 
appears  to  have  its  blood  oxygenated  at  the  extremities  of  the 
veflels  lurrounding  the  yolk  ;  which  are  fpread  on  the  air-bag 
at  the  broad  end  of  the  egg,  and  may  abforb  oxygene  through 
that  moid  membrane  from  the  air  confined  behind  it ;  and  which 
is  (hewn  by  experiments  in  the  exhausted  receiver  to  be  change- 
able^ through  the  (hell  See  Phy'tologia,  Sett.  III. 

This  analogy  may  even  be  extended  to  the  growing  feeds  of 
vegetables  -,  which  were  (hewn  by  Mr.  Scheele  to  require  a  reno- 
vation of  the  air  over  the  water,  in  which  they  were  confined. 
Many  vegetable  feeds  are  furrounded  with  air  in  their  pods  or 
receptacles,  as  peas,  the  fruit  of  itaphylea,  and  lichnis  veficaria  5 
but  it  is  probable,  that  thofe  feeds  after  they  are  flied,  as  well  as 
the  fpawn  of  filli,  by  the  fituation  of  the  former  on  or  near  the 

VOL.  I.  Z  z  moift 


37P  OXYGENATION    SECT.  XXXVIIL  3.  i. 

moid  and  aerated  furface  of  the  earth,  and  of  the  latter  in  the 
ever-changing  and  ventilated  water,  may  not  be  in  need  of  an 
apparatus  for  the  oxygenation  of  their  firlt  blood,  before  the 
leaves  of  one,  and  the  gills  of  the  other,  are  produced  for  this 
purpofe.  See  Phytologiaj  Se6r,.  III. 

III.  I.  There  are  many  arguments,  betides  the  drift  analogy 
between  the  liquor  amnii  and  the  albumen  ovi,  which  (hew  the 
former  to  be  a  nutritive  fluid  ;  and  that  the  fetus  in  the  latter 
months  of  pregnancy  takes  it  into  its  ftomach  ;  and  that  in  con- 
fequence  the  placenta  is  produced  for  fome  other  important 
purpofe. 

Firft,  that  the  liquor  amnii  is  not  an  excrementitious  fluid  is 
evinced,  becaufe  it  is  found  in  greater  quantity,  when  the  fetus 
is  young,  decreafmg  after  a  certain  period  till  birth.  Haller  af- 
ferts, "  that  in  fome  animals  but  a  fmall  quantity  of  this  fluid  re- 
mains at  the  birth.  In  the  eggs  of  hens  it  is  confumed  on  the 
eighteenth  day,  fo  that  at  the  exclufion  of  the  chick  fcarcely  any 
remains.  In  rabbits  before  birth  there  is  none."  Elem.  Phyfiol. 
Had  this  been  an  excrementitious  fluid,  the  contrary  would 
probably  have  occurred.  Secondly,  the  fkin  of  the  fetus  is  cov- 
ered with  a  whitim  cruft  or  pellicle,  which  would  feem  to  pre- 
clude any  idea  of  the  liquor  amnii  being  produced  by  any  exu- 
dation of  perfpirable,  matter.  And  it  cannot  confift  of  urine, 
becaufe  in  brute  animals  the  urachus  pafles  from  the  bladder  to 
the  alantois  for  the  exprefs  purpofe  of  carrying  off  that  fluid  ; 
•which  however  in  the  human  fetus  feems  to  be  retained  in  the 
diftended  bladder,  as  the  feces  are  accumulated  in  the  bowels  of 
all  animals. 

2.  The   nutritious  quality  of  the  liquid,  which  furrounds  the 
fetus,  appears  from  the  following  confiderations.      i.   Itisco- 
agulable   by   heat,  by  nitrous  acid,  and  by  fpirit  of  wine,  like, 
milk,  ferum   of  blood,  and  other  fluids,   which  daily  experience 
evinces  to  be  nutritious.     2.   It  has   a  faltifh  tafte  according  to 
the  accurate  Baron   Haller,  not  unlike  the  whey  of  milk,  which 
it  even  refembles  in  fmell.     3.    The  white  of  the    egg  which 
conftitutes  the  food  of  the  chick,  is  (hewn  to  be  nutritious   by 
our  daily  experience  ;   befides  the  experiment  of  its  nutritious 
efFefts   mentioned  by  Dr.   Fordyce   in  his  late  Treatife  on  Di- 
geftion,  p,  178  ;   who  adds,  that  it  much  refembles  the  effential 
parts  of  the  ferum  of  blood. 

3.  A  fluid  fimilar  to  the  fluid,  with  which  the  fetus  is  fur- 
rounded,  except  what  little  change  may  be  produced  by  a  begin- 
ning digeftion,  is   found  in  the  fame    manner  in  the  ftomach  of 
the  chick, 

Numerous  hairs,  fimilar  to  thofe  of  its  Ikin,  are  perpetually 

found 


SECT.  XXXVIIL  3.3.        OF  BLOOD.  371 

found  among  the  contents  of  the  ftomach  in  new-born  calves  ; 
which  rnuft  therefore  have  licked  themfelves  before  their  nativi- 
ty. Blafii  Anatom.  See  Sea.  XVI.  2.  on  Inftinfl:. 

The  chick  in  the  egg  is  feen  gently  to  move  in  its  furround- 
ing  fluid,  and  to  open  and  ftiut  its  mouth  alternately.  The 
fame  has  been  obferved  in  puppies.  Halter's  El.  Phyf.  I.  8. 
p.  201. 

A  column  of  ice  has  been  feen  to  reach  down  the  cefophagus 
from  the  mouth  to  the  ftomach  in  a  frozen  fetus  ;  arid  this  ice 
was  the  liquor  amnii  frozen. 

The  meconium,  or  firft  feces,  in  the  bowels  of  new-born  in- 
fants evince,  that  fomething  has  been  digefted  ;  and  what  could 
this  be  but  the  liquor  amnii  together  with  the  recrements  of  the 
gaftric  juice  and  gall,  which  were  neceflary  for  itsdigeftion  ? 

Another  argument  to  evince,  that  the  fetus  is  nourifhed  by  al- 
iment taken  into  the  ftomach  and  inteftincs  by  the  mouth  dur- 
ing the  latter  months  of  pregnancy,  may  be  deduced  from  the 
liver  of  the  fetus  ;  which  Haller  obferves  to  be  very  large  ;  not 
like  the  lungs,  as  if  defigned  for  the  future  man  after  nativity. 
Phyfiol.  Vol.  VI.  p.  618.  Whence  a  fecretion  of  bile  mud  al- 
ready exift,  which  can  ferve  no  purpofe  but  to  be  mixed  with 
the  digefting  aliment. 

There  have  been  recorded  fome  monftrous  births  of  animals 
without  heads,  and  confequently  without  mouths,  which  feem 
to  have  been  delivered  on  doubtful  authority,  or  from  inaccurate 
obfervation.  There  are  two  of  fuch  monftrous  productions 
however  better  attefted  ;  one  of  a  human  fetus,  mentioned  by 
Gipfon  in  the  Scots  Medical  Eflays  ;  which  having  the  gula  im- 
pervious was  furnifhed  with  an  aperture  into  the  wind-pipe, 
which  communicated  below  into  the  gullet ;  by  means  of  which 
the  liquor  amnii  might  be  taken  into  the  ftomach  before  nativity 
without  danger  of  fufFocation,  while  the  fetus  had  no  occafion 
to  breathe.  The  other  monftrous  fetus  is  defcribed  by  Vander 
Wiel,  who  aflerts  that  he  faw  a  monftruous  lamb,  which  had  na 
mouth  ;  but  in  (lead  of  it  was  furnifhed  with  an  opening  in  the 
lower  part  of  the  neck  into  the  ftomach.  Both  thefe  inftances 
evidently  favour  the  doftrine  of  the  fetus  being  nourifhed  by  the 
mouth  5  as  otherwife  there  had  been  no  neceflity  for  new  or 
unnatural  apertures  into  the  ftomach,  when  the  natural  ones 
were  deficient. 

From  thefe  fa<Sls  and  obfervations  we  may  fafely  infer,  that 
the  fetus  in  the  womb  is  nouriftied  by  the  fluid  which  furrounds 
it  •,  which  during  the  firft  period  of  geftation  is  abforbed  by  the 
naked  lafteals  •,  and  is  afterwards  fwallowed  into  the  ftomach 
and  bowels,  when  thefe  organs  are  perfected  5  and  laftlythat 

the 


372  OXYGENATION,  &c.     SECT.  XXXVIII,  3.  3. 

the  placenta  is  an  organ  for  the  purpofe  of  giving  due  oxygena- 
tion  to  the  blood  of  the  fetus ;  which  is  more  neceflary,  or  at 
leaft  more  frequently  neceflary,  than  even  the  fupply  of  food. 
The  queftion  of  the  great  Harvey  becomes  thus  eafily  anfwer- 
cd.  "  Why  is  not  the  fetus  in  the  womb  fuffocated  for  want 
of  air,  when  it  remains  there  even  to  the  tenth  month  without 
refpiration  :  yet  if  it  be  born  in  the  feventh  or  eighth  month, 
and  has  once  refpired,  it  becomes  immediately  fuffocated  for 
want  of  air,  if  its  refpiration  be  obftrufted  ?" 

For  further  information  on  this  iubjeft,  the  reader  is  referred 
to  the  Tentamen  Medicum  of  Dr.  Jeffray,  printed  at  Edinburgh 
in  1786.  And  it  is  hoped  that  Dr.  Forefter  will  fome  time 
give  his  thefes  on  this  fubjeft  to  the  public. 


SECT, 


SECT.  XXXDC.  GENERATION,  373 

SECT.      XXXIX. 


OF    GENERAITON. 


Felix,  qui  caufas  alta  caligine  merfas 

Pandit,  et  evolvit  tenuiflima  vincula  rerun*.    ANON. 

-I.  Habits  ofacJing  and  feeling  of  individuals  attend  the  foul  into  a 
future  life^  and  attend  the  nerw  embryon  at  the  time  of  its  produc~ 
tion.  The  new  fpeck  of  entity  abjorbs  nutriment,  'and  receives 
oxygene.  Spreads  the  terminations  of  its  ve/Jels  on  cells ,  •which 
communicate  with  the  arteries  of  the  uterus  ;  Jometimes  'with  thofe 
of  the  peritoneum.  Afterwards  it  fwallows  the  liquor  amnii, 
•which  it  produces  by  its  irritation  from  the  uterus^  or  peritoneum. 
Like  infefts  'in  the  heads  of  calves  andjheep  Why  the  white  of 
egg  is  of  two  con/tftences.  Why  nothing  is  found  in  quadrupeds 
jimilar  to  the  yolk,  nor  in  moft  vegetable  feeds.  II.  I.  Eggs 
of  frogs  and  jft/h  impregnated  out  of  their  bodies.  Eggs  of  fowls 
•which  are  not  fecundated,  contain  only  the  nutriment  of  the  embry- 
on. *Ihe  embryon  is  produced  by  the  male,  and  the  nutriment  by 
the  female  Animalcula  in  femine.  Profufion  of  nature's  births. 
2.  Vegetables  viviparous.  Buds  and  bulbs  have  each  a  father  but 
no  mother.  Veffels  of  the  leaf  and  bud  inofculate.  The  paternal 
efeml' 


^spring  exacJly  refembles  the  parent  3 .  In/eels  impregnated  for 
Jtx  generations*  Polypus  branches  like  buds  Creeping  roots. 
Viviparous  flowers.  Tania,  volvox.  Eve  from  Adam's  rib. 
Semen  not  a  Jlimulus  to  the  egg.  III.  I  Embryons  not  original- 
ly created  within  other  embryons  Organized  matter  is  not  Jo  mi- 
nute. 2.  All  the  parts  of  the  embryon  are  not  firmed  in  the  male 
parent.  Crabs  produce  their  legs,  'worms  produce  their  heads  and 
tails.  In  wens,  cancer 's,  and inflammations ,  neiuvejjelt  are  form- 
ed. Mules  partake  of  the  forms  ff  both  parents.  Hair  and 
nails  grow  by  elongation,  not  by  diflenticn.  3.  Organic  particles 
of  Buff  on.  IV.  I.  Rudiment  of  the  embryon  a  Jimple  living  Jita* 
ment)  becomes  a  living  ring,  and  then  a  living  tube.  2.  It  ac- 
quires new  irr liabilities >  and  fenftbilities  with  new  organizations, 
as  in  wounded  fnails,  polypi,  moths,  gnats,  tad-poles*  Hence  new 
parts  are  acquired  by  addition  not  by  di/tention.  3.  All  parts  of 
the  body  grow  if  not  confined.  4.  Fetufes  deficient  at  their  ex- 
tremities, or  have  a  duplicature  of  parts.  Monflrous  birthst 
Double  parts  of  vegetables.  5 ,  Mules  cannot  be  formed  by  dif- 
tention  of  thefeminalens.  6.  Families  of  animals  from  a  mix- 
ture of  their  orders.  Mules  imperfecl.  7,  Animal  appetency 
like  chemical  affinity.  Visfatricatrix  and  medicatrix  of  nature, 

8.  The 


374  GENERATION.  SECT.  XXXIX- 

8.  The  clanges  of  animals  before  and  after  nativity.  Similarity 
of  their  Jlrufture.  Changes  in  them  from  luft>  hunger,  and 
danger.  All  warm-blooded  animals  derived  from  one  living  filament* 
Cold  blooded  animals ,  infecls^  worms ,  vegetables,  derived  alfofrom 
one  living  filament.  Male  animals  have  teats.  Male  pigeon  gives 
milk.  The  world  itf elf  generated.  The  caufe  ofcaufes.  AJlate  of 
probation  and  refponfibility.  V.  I .  Efficient  caufe  of  the  colours  of 
birds'  eggs,  and  of  hair  and  feathers, which  become  white  infnowy 
countries.  Imagination  of  the  female  colours  the  egg.  Ideas  or 
motions  cf  the  retina  imitated  by  the  extremities  of  the  nerves  of 
touch)  or  rete  mucofum.  2.  Nutriment  fupplied  by  the  female  of 
three  kinds.  Her  imagination  can  only  affecl  the  firft  kind. 
Mules  how  produced^  and  mulattoes.  Organs  of  reproduction  why 
deficient  in  mules.  Eggs  with  double  yolks.  VI.  I.  Various  fe- 
cretions  produced  by  the  extremities  of  the  veffels,  as  in  the  glands. 
Contagious  matter.  Many  glands  affected  by  pleafurable  ieleas, 
as  thofe  which  fecrete  the  femen.  2.  Snails  and  worms  are  her- 
maphrodite, yet  cannot  impregnate  themfelves.  Final  caufe  of 
this.  3.  The  imagination  oj  the  male  Jurms  the  fex.  Ideas,  or 
motions  of  the  nerves  of  vifion  or  of  touch,  are  imitaied  by  the  ulti- 
mate extremities  of  the  glands  of  the  tejlesy  which  mark  thefex. 
This  ejfecl  of  the  imagination  belongs  only  to  the  male.  The  f ex  of 
the  embryon  is  not  owing  to  accident.  4.  Caufes  of  the  changes  in 
animals  from  imagination  as  in  monfters.  From  the  male.  From 
the  female.  5.  Mifcarriages  from  fear.  6.  Power  of  the 
imagination  of  the  male  over  the  cdoury  form  ^  and  f  ex  of  the  prog- 
eny. An  inftance  of.  *]»  A  El  of  generation  accompanied  with 
Ideas  of  the  male  or  female  form.  Art  of  begetting  beautiful  chil- 
dren of  either  f  ex.  VII.  Recapitulation.  VIII  i.  Appendix. 
Suds  are  individuals.  Conft/i  of  plumula  caudex  and  radicle. 
Every  part  of  the  caudex  can  germinate.  A  triple  tree  by  ingraft- 
ment.  A  lateral  vegetable  mule  produced  by  three  parents.  Con- 
ferva fontinalis.  2.  Lateral  propagation  of  polypus,  and  hydra 
Jlentorea.  The  halves  of  two  polypi  made  to  unite.  Ingraftment 
of  vegetables.  Lateral  mule.  3,  New  bud  of  a  doubly  ingrafted 
tree  has  three  kinds  of  caudex.  Triple  mule  produced  from  vari- 
ous parts  of  the  parent  tree.  4.  Earthworms  cut  af under  gener- 
ate a  new  heady  and  a  new  tail.  So  the  caudex es  of  the  buds  of 
treet.  The  whole  embryon  not  formed  at  the  fame  time.  £.  Parts 
of  the  long  caudex  of  the  new  bud  are  fecreted from  correfpondent 
parts  of  the  parent  bud  and  unite  beneath  the  cuticle.  Every 
part  of  the  caudex  can  germinate.  Thefe  new  buds  refemble  the 
partofthejlocky,  'where  they  arife.  Lateral  mule  from  many 
parents.  If  a  triple  fexual  mule?  6.  Gravitation^  chemical 
affinity,  elettricit^  magnetifm.  Power  to  attract.  Aptitude  to 

be 


SfiCT.  XXXIX.  GENERATION.  375 

be  at  tr  a  fled.  A  magnet  pojpjjes  power  to  attracl,  Iron  an  aptitude 
to  be  attracted.  So  of  electrified  bodies ,  and  chemical  affinities. 
Or  two  bodies  may  reciprocally  attract  each  other.  7.  Union  of 
animal  with  inanimate  matter.  Union  of  two  living  particles. 
'The  animal  fenfe  poffejjes  appetency  to  unite,  the  inanimate  materi- 
al pojjejjes  aptitude  to  be  united.  Vitality  of  the  blood.  Fibrils 
with  appetencies,  molecules  with  propenftties*  8.  Fibrils  •with 
formative  appetencies.  Molecules  with  formative  propenfities. 
Like  Jingle  and  double  affinities.  PaJJtons  of  hunger  and  of  love. 
Thirjl.  Suckling  children.  Mode  of  lateral  propagation.  9. 
Superfluous  vital  particles  produced  in  the  blood.  Secreted  by  fex- 
ual  glands.  Combine  beneath  the  cuticle  of  trees.  Acquire  new 
appetencies,  and  form  fecondary  parts  of  the  embryon.  So  the 
paffton  for  generation >  and  defire  for  animal  food,  and  the  new  at- 
traElions  of  bodies  chemically  combined.  New  molecules  are  form- 
ed by  the  fexual  glands  at  puberty,  and  in  the  pectoral  ones.  10. 
Different  fibrils  and  molecules  are  detached  from  different  parts 
of  the  parent  caudex  to  form  the  filial  one  :  fo  in  the  fexual  propa- 
gation of  vegetables  :  and  by  their  combination  produce  an  embry- 
on) and  acquire  new  appetencies  and  form  fecondary  parts,  as  in 
dioecious  flowers.  II.  Threefold  lateral  mules*  So  fexual  mules 
refemble  parts  of  their  parents  according  to  the  combinations  of  the 
fibrils  and  molecules ,  and  produce  fecondary  parts,  other  wife  they 
would  refemble  the  father  only.  Epigram  from  Martial.  IX. 
I .  Various  parts  of  the  new  embryon  produced  at  the  fame  time. 
Organized  bodies  too  large  to  befecreted.  Primary  and  fecondary 
formation  of  parts  of  the  fetus.  M.  Buffon's  theory  differs  from 
this.  Moles  and  monjlrous  births.  An  embryon  is  not  an  in- 
dividual >  till  the  nerves  unite  in  the  brain.  2.  The  brain  and 
heart  generated  at  the  fame  time.  3.  Organic  particle  too  large 
to  pafs  the  glands  and  capillaries.  Not  fo  the  formative  particles. 
Hence  the  latter  cannot  combine  in  the  blood.  4.  Formative  par- 
ticles do  not  combine  in  the  receptacles  of  the  fexuat  glands  >  as  thofs 
of  the  male  differ  from  thofe  of  the  female.  Not  fo  in  Bufforfs 
theory.  5.  "The  whole  embryon  not  produced  at  the  fame  time. 
Primary  and  fecondary  parts.  Secondary  formation  of  the  caudex 
of  buds  >  of  diffevered  earth  worms  >  of  the  legs  of  crabs,  of  human 
teeth ',  and  of  a  thumb.  X.  I.  Solitary  lateral  generation,  and 
folitary  internal  generation.  Animalized  particles  of  primary 
combination,  are  fecreted  ^combine  y  and  form  primary  organizations. 
The  caudex  gemma  produce  fecondary  parts,  and  commences  its 
formation  in  federal  places  at  the  fame  time.  Refembles  the  parent 
more  than  a  fexual  progeny.  The  polypus  and  hydra.  2.  Solita- 
ry internal  generation  of  aphis,  tenia,  aclinia9  votvcX)  produces  a 
viviparous  offspring^  not  an  oviparous  one.  Difference  of  lateral 

and 


376  GENERATION.         SECT.  XXXIX. 

and  internal  generation.  3.  Hermaphrodite  fexual  generation 
in  moft  flowers*  and  fome^  infers  Summit-bulbs  of  feme  vegeta- 
bles are  a  fexual  progeny.  Sexual  organs  in  hermaphrodites  are 
feparate,  but  fecrete  the  mafculine  and  feminine  formative  particles 
from  the  fame  mafs  of  blood  Why  feedling  apple-trees  fometime* 
refemble  the  parent,  fometimes  not.  Number  offpecies  increased  by 
reciprocal  generation.  4.  In  fimple  fexual  generation  the  mafcu- 
line and.  feminine  fecretions  are  from  different  majjes  of  blood. 
Thefe  animals  were  originally  hermaphrodites  The  mode  of  the 
producJitn  of  the  new  embryon.  Secretion  differs  from  nutrition. 
New  embryon  begins  in  more  parts  than  one.  Acquires  new  ap- 
petencies^ and  fabricates  fecondary  parts*  Sexual  organs  are  fecon- 
dary  parts,  not  primary  ones.  So  is  the  difference  of  the  male  and 
female  forms.  Vegetable  and  animal  fecondary  productions.  5. 
Seeds  Eggs  Spawn  differs  from  eggsy  as  it  enlarges  along  with 
the  embryon  like  the  membranes  of  the  fetus  in  utero.  XL  i.  in- 
animate cryjlals.  Animated  organization.  Microjcopic  animal- 
cula  from  Jlagnaiion  of  vegetable  and  animal  fluids  Do  not 
generate.  2.  Second  kind  of  animal  production  commences  in  more 
points  than  one  :  not  like  microfcopic  animals  ;  as  truffles,  fungi^ 
polypi,  hydra.  3.  Other  vegetables  are  hermaphrodite^  but  both 
their  fexual  glands  fecrete  from  the  fame  mafi  of  blood.  4.  Other 
vegetables  have  acquired  feparate  fcxes*  and  fecrete  the  prolific  flu- 
ids from  different  maffes  of  blood.  The  embryon  begins  in  more 
points  in  the  more  complicated  animals.  The  primary  parts  fabri- 
cate fecondary  ones,  as  in  the  clafs  dioecia  of  vegetables,  and  in  fexu- 
al animals.  Nature  it  yet  in  her  infancy.  5  Spontaneous  pro- 
duction of  microfcopic  animalcules.  Isftmilar  to  actual  generation. 
Thefirft  animalcules  generate  others,  and  improve.  Seedling  tu- 
lip-root. Aphis.  Immutable  laws  impreffid  on  matter.  XII. 
Conclufion.  Of  caufe  and  effect.  The  atomic  philofophy  leads  to 
a  firft  caufe. 


I.  THE  ingenious  Dr.  Hartley  in  his  work  on  man,  and  fome 
other  philosophers,  have  been  of  opinion,  that  our  immortal 
part  acquires  during  this  life  certain  habits  of  action  or  of  fenti- 
ment,  which  become  for  ever  indifloluble,  continuing  after  death 
in  a  future  ftate  of  exiftence  ;  and  add,  that  if  thefe  habits  are 
of  the  malevolent  kind,  they  mud  render  the  poflefibr  miferable 
even  in  Heaven  I  would  apply  this  ingenious  idea  to  the  gener- 
ation or  production  of  the  embryon,  or  new  animal,  which 
partakes  fo  much  of  the  form  and  propenfities  of  the  parent. 

Owing  to  the  imperfe&ion  of  language  the  offspring  is  termed 
a  new  animal,  but  is  in  truth  a  branch  or  elongation  of  the  par- 
ent *,  fmce  a  part  of  the  embryon-animal  is,  or  was,  a  part  of  the 

parent , 


SECT.  XXXIX.  i.  i.       GENERATION.  377 

parent ;  and  therefore  in  drift  language  it  cannot  be  faid  to  be 
entirely  new  at  the  time  of  its  production  ;  and  therefore  it  may 
retain  fome  of  the  habits  of  the  parent-fyftem. 

At  the  earlieft  period  of  its  exiftence  the  embryon,  as  fecreted 
from  the  blood  of  the  male,  would  feem  to  confift  of  a  living 
filament,  with  certain  capabilities  of  irritation,  fenfation,  voli- 
tion, and  aflbciation  ;  and  alfo  with  fome  acquired  habits  or  pro- 
penfities  peculiar  to  the  parent :  the  former  of  thefe  are  in 
common  with  other  animals  •,  the  latter  feem  to  diflinguifh  or 
produce  the  kind  of  animal,  whether  man  or  quadruped,  with 
the  fimilarity  of  feature  or  form  to  the  parent.  It  is  difficult  to 
be  conceived,  that  a  living  entity  can  be  feparated  or  produced 
from  the  blood  by  the  action  of  a  gland  ;  and  which  (hall  after- 
wards become  an  animal  fimilar  to  that  in  whofe  veflels  it  is 
formed ;  even  though  we  fhould  fuppofe  with  fome  modern 
theorifts,  that  the  blood  is  alive  ;  yet  every  other  hypothefis  con- 
cerning generation  reds  on  principles  (till  more  difficult  to  our 
comprehenfion. 

At  the  time  of  procreation  this  fpeck  of  entity  is  received  in- 
to an  appropriated  nidus,  in  which  it  muft  acquire  twocircum- 
ftances  neceflary  to  its  life  and  growth ;  one  of  thefe  is  food  or 
fuftenance,  which  is  to  be  received  by  the  abforbent  mouths  of 
its  veffels  ;  and  the  other  is  that  part  of  atmofpherical  air,  or  of 
water,  which  by  the  new  chemiftry  is  termed  oxygene,  and 
which  affedts  the  blood  by  paffing  through  the  coats  of  the  vef- 
fels which  contain  it.  The  fluid  furrounding  the  embryon  in  its 
new  habitation,  which  is  called  liquor  amnii,  fupplies  it  with 
nourifhment ;  and  as  fome  air  cannot  but  be  introduced  into  the 
uterus  along  with  a  new  embryon,  it  would  feem  that  this  fame 
fluid  would  for  a  fhort  time,  fuppofe  for  a  few  hours,  fupply 
likewife  a  fufficient  quantity  of  the  oxygene  for  its  immediate 
exiftence. 

On  this  account  the  vegetable  impregnation  of  aquatic  plants 
is  performed  in  the  air  ;  and  it  is  probable  that  the  honey -cup 
or  ne£tary  of  vegetables  requires  to  be  open  to  the  air,  that  the 
anthers  and  fligmas  of  the  flower  may  have  food  of  a  more 
oxygenated  kind  than  the  common  vegetable  fap-juice. 

On  the  introduction  of  this  primordium  of  entity  into  the 
uterus  the  irritation  of  the  liquor  amnii,  which  furrounds  it, 
excites  the  abforbent  mouths  of  the  new  veflels  into  adtion  ;  they 
drink  up  a  part  of  it,  and  a  pleafurable  fenfitf  ion  accompanies 
this  new  action  ;  at  the  fame  time  the  chemical  affinity  of  the 
oxygene  afts  through  the  veflels  of  the  rubefcent  blood  -9  arid  a 
previous  want,  or  difagreeable  fenfation,  is  relieved  by  this 
procefs. 

VOL.  I-  A  A  a  As 


378  GENERATION.        SECT.  XXXIX.  i.  i. 

As  the  want  of  this  oxygenation  of  the  blood  is  perpetual,  (as 
appears  from  the  incefTant  necefiity  of  breathing  by  lungs  or 
gills,)  the  vefTels  become  extended  by  the  efforts  of  pain  or  defire 
to  feek  this  neceflary  object  of  oxygenation,  and  to  remove  the 
difagreeable  fenfation,  which  that  want  occafions.  At  the  fame 
time  new  particles  of  matter  are  abforbed,  or  applied  to  thefe 
extended  veiTels,  and  they  become  permanently  elongated,  as  the 
fluid  in  contact  with  them  foon  lofes  the  oxygenous  part,  which 
it  at  fir  ft  poflefled,  which  was  owing  to  the  introduction  of  air 
along  with  the  embryon.  Thefe  new  blood-vefTels  approach  the 
fides  of  the  uterus,  and  penetrate  with  their  fine  terminations 
into  the  veiTels  of  the  mother;  or  adhere  to  them,  acquiring 
oxygene  through  their  coats  from  the  paffing  currents  of  the  ar- 
terial blood  of  the  mother.  See  Sed.  XXXVIII.  2. 

This  attachment  of  the  placental  veflels  to  the  internal  fide  of 
the  uterus  by  their  own  proper  efforts  appears  further  illuftrated 
by  the  many  inftances  of  extra-uterine  fetufes,  which  have  thus 
attached  or  inferted  their  veflels  into  the  peritoneum  •,  or  on  the 
vifcera,  ex^ftly  in  the  fame  manner  as  they  naturally  iniert  or 
attach  them  to  the  uterus. 

The  abforbent  veflels  of  the  embryon  continue  to  drink  up 
nourifhment  from  the  fluid  in  which  they  fwim,  or  liquor  am- 
nii ;  and  which  at  firlt  needs  no  previous  digeitive  preparation  ; 
but  which,  when  the  whole  apparatus  of  digeftion  becomes  com- 
plete, is  fwallowed  by  the  mouth  into  the  ftomach,  and  being 
mixed  with  faliva,  gaflric  juice,  bile,  pancreatic  juice,  and  mucus 
of  the  inteftines,  becomes  digefted,  and  leaves  a  recrement, 
which  produces  the  firfl  feces  of  the  infant,  called  meconium. 

The  liquor  amnii  is  fecreted  into  the  uterus,  as  the  fetus  re- 
quires it,  and  may  probably  be  produced  by  the  irritation  of  the 
fetus  as  an  extraneous  body  j  fince  a  fimilar  fluid  is  acquired, 
from  the  peritoneum  in  cafes  of  extra-uterine  geftation.  The 
young  caterpillars  of  the  gad-fly  placed  in  the  fkins  of  cows,  and 
the  young  of  the  ichneumon-fly  placed  in  the  backs  of  the  cater- 
pillars on  cabbages,  feem  to  produce  their  nourifhment  by  their 
irritating  ,the  fides  of  their  nidus.  A  vegetable  fecretion  and 
concretion  .are  thus  produced  on  oak-leaves  by  the  gall-infect, 
and  by  the  cynips  in  the  bedeguar  of  the  rofe  j  and  by  the  young 
grafshopper  on  many  plants,  by  which  the  animal  furrounds  it- 
felf  with  froth.  But  in  no  circumftance  is  extra-uterine  gefta- 
tion  fo  exactly  resembled  as  by  the  eggs  of  a  fly,  which  are  de- 
pofited  in  the  frontal  finus  of  (heep  and  calves  Thefe  eggs  float 
in  fome  ounces  of  fluid  collected  in  a  thin  pellicle  or  hydatid. 
This  bag  of  fluid  comprefles  the  optic  nerve  on  one  fide,  by  which 
the  vifion  being  lefs  diftinct  in  that  eye,  the  animal  turns  in  per- 
petual 


SECT.  XXXIX.  i.  i.       GENERATION.  379 

petual  circles  towards  the  fide  affe&ed,  in  order  to  get  a  more 
accurate  view  of  objefts  ;  for  the  fame  reafon  as  in  fquinting 
the  affeded  eye  is  turned  away  from  the  object  contemplated. 
Sheep  in  the  warm  months  keep  their  nofes  clofe  to  the  ground 
to  prevent  this  fly  from  ib  readily  getting  into  their  nodrils. 

The  liquor  amnii  is  fecreted  into  the  womb  as  it  is  required, 
not  only  in  refpect  to  quantity,  but,  as  the  digeftive  powers  of 
the  fetus  become  formed,  this  fluid  becomes  of  a  different  con- 
fidence and  quality,  till  it  is  changed  for  milk  after  nativity. 
Haller,  Phyfiol  V.  i.  In  the  egg  the  white  part,  which  is 
analogous  to  the  liquor  amnii  of  quadrupeds,  confifls  of  two 
didinct  parts  ;  one  of  which  is  more  vifcid,  and  probably  more 
difficult  of  digeftion,  and  more  nutritive  than  the  other ;  and 
this  latter  is  ufed  in  the  lad  week  of  incubation.  The  yolk  of 
the  egg  is  a  dill  dronger  or  more  nutritive  fluid,  which  is  drawn 
up  into  the  bowels  of  the  chick  jud  at  its  exclufion  from  the 
fhell,  and  ferves  it  for  riourifhment  for  a  day  or  two,  till  it  is 
able  to  diged,  and  has  learnt  to  choofe  the  harder  feeds  or  grains, 
which  are  to  afford  it  fudenance.  Nothing  analogous  to  this 
yolk  is  found  in  the  fetus  of  la£liferous  animals,  as  the  milk  is 
another  nutritive  fluid  ready  prepared  for  the  young  progeny ; 
it  is  alfo  a  curious  circumdance,  that  the  fird  milk  of  female  ani- 
mals after  parturition  is  much  thicker,  like  the  yolk  of  egg,  and 
much  more  coagulable,  than  that  which  is  fecreted  after  a  few 
days,  when  the  digedive  powers  of  the  offspring  are  become 
ftronger. 

The  yolk  therefore  is  not  neceffary  to  the  fpawn  of  fifh,  the 
eggs  of  infects,  or  for  the  feeds  of  vegetables  ;  as  their  embry- 
ons  have  probably  their  food  prefented  to  them  as  foon  ns  they 
are  excluded  from  their  (hells,  or  have  extended  their  roots. 
Whence  it  happens  that  fome  infects  produce  a  living  progeny 
in  the  fpring  and  fummer,  and  eggs  in  the  autumn ;  and  fome 
vegetables  have  living  roots  or  buds  produced  in  the  place  of 
feeds,  as  the  polygonum  viviparum,  and  magical  onions.  S^e 
Botanic  Garden,  p.  ii.  art.  Anthoxanthum. 

There  feems  however  to  be  a  refervoir  of  nutriment  prepared 
for  fome  feeds  befides  their  cotyledons  or  feed-leaves,  which  may 
be  fuppofed  in  fome  meafure  analogous  to  the  yolk  of  the  egg. 
Such  are  faccharine  juices  of  apples,  grapes,  and  other  fruits, 
which  fupply  nutrition  to  the  feeds  after  they  fall  on  the  ground. 
And  which  is  the  milky  juice  in  the  centre  of  the  cocoa-nut,  and 
part  of  the  kernel  of  it ;  the  fame  I  fuppofe  of  all  other  monoco- 
tyledon feeds,  as  of  the  palms,  graifes,  and  lilies.  The  milky 
juice  in  the  centre  of  the  cocoa-nut  feems  curioufly  to  referable 
the  chyle  of  animals,  as  it  contains  oil  diffufed  with  mucilage 

and 


38o  GENERATION.       SECT.  XXXIX.  2.  i. 

and  fugar,  whence  arifes  its  white  colour  ;  whereas  the  chyle  or 
fap-juice  of  vegetables,  which  exudes  from  wounds  of  birch  or 
maple-trees  in  the  vernal  months,  is  tranfparent,  and  confifts  on- 
ly of  fugar  and  mucilage,  and  in  this  circumftance  differs  from 
the  chyle  of  animals. 

II  i.  The  procefs  of  generation  is  flill  involved  in  impene- 
trable obfcurity  ;  conjectures  may  neverthelefs  be  formed  con- 
cerning fome  of  its  circumftances.  Firft,  the  eggs  of  fifh  and 
frogs  are  impregnated,  after  they  leave  the  body  of  the  female  ; 
becaufe  they  are  depofited  in  a  fluid,  and  are  not  therefore 
covered  with  a  hard  fhell.  It  is  however  remarkable,  that  neither 
frogs  nor  fifli  will  part  with  their  fpawn  without  the  prefence 
of  the  male ;  on  which  account  female  carp  and  gold-fifh  in 
fmall  ponds  where  there  are  no  males,  frequently  die  from  the 
diftention  of  their  growing  fpawn.  2.  The  eggs  of  fowls, 
which  are  laid  without  being  impregnated,  are  feen  to  contain 
only  the  yolk  and  white,  which  are  evidently  the  food  or  fuf- 
tenance  for  the  future  chick.  3.  As  the  cicatricula  of  thefe 
eggs  is  given  by  the  cock,  and  is  evidently  the  rudiment  of  the 
new  animal ;  we  may  conclude,  that  the  embryon  is  produced 
by  the  male,  and  the  proper  food  and  nidus  by  the  female.  For 
if  the  female  be  fuppofed  to  form  an  equal  part  of  the  embryon, 
why  fliould  (he  form  the  whole  of  the  apparatus  for  nutriment 
and  for  oxygenation  ?  The  male  in  many  animals  is  larger, 
ftronger,  and  digefts  more  food  than  the  female,  and  therefore 
fhould  contribute  as  much  or  more  towards  the  reproduction  of 
the  fpecies  ;  but  if  he  contributes  only  half  the  embryon  and 
none  of  the  apparatus  for  fuftenance  and  oxygenation,  the  di- 
vifion  is  unequal  •,  the  ftrength  of  the  male,  and  his  confump- 
tion  of  food  are  too  great  for  the  erFeft,  compared  with  that  of 
the  female,  which  is  contrary  to  the  ufual  courfe  of  nature. 

It  has  been  fuppofed  by  fome  inquirers  into  the  procefs  of 
generation,  that  the  male  femen  in  many  animals  could  not  come 
into  contact  with  the  ovum  of  the  female,  and  they  have  hence 
fuppofed,  that  an  aerial  and  ethereal  emanation  from  the  femen 
virile  might  ferve  the  purpofe  of  Simulating  into  life  the  ovum 
muliebre,  becaufe  in  the  vegetable  ftigma  of  fome  flowers  no 
veflels  have  been  feen  to  receive  and  tranfmit  the  burfting  an- 
ther duft  j  and  becaufe  it  is  not  poflible,  that  the  ejaculatio 
feminis  in  quadrupeds  could  fend  it  through  the  fallopian  tubes 
to  the  veficles  of  the  ovaria. 

Inrefpeclto  the  analogies  from  other  animals,  i  ft,  It  may 
be  obferved,  that  in  the  generation  of  frogs,  it  is  well  known, 
that  the  male  fperm  is  effufed  in  contadl  with  the  female  fpawn, 
as  it  leaves  her  body,  and  that  in  fifh  the  male  fperm  is  likewife 

effufed 


SECT.  XXXIX.  2.  i.      GENERATION.  381 

effufed  on  the  female  fpawn  after  its  production.  2d.  In  refpect 
to  vegetables,  it  muft  be  recollected,  that  their  veflels  are  fo  mi- 
nute in  diameter,  that  they  have  not  in  general  been  of  fufficient 
fize  to  be  injected  by  coloured  fluids  ;  and  are  not  thence  fo 
vifible  by  microfcopes  as  thofe  of  animals,  and  that  it  is  probable, 
thofe  of  the  ftigma  or  piftillum  of  flowers,  which  are  defigned 
to  abforb  the  folution  of  the  anther-duft,  which  adheres  to  the 
moift  ftigma,  may  be  always  empty,  or  have  their  mouths  clofed, 
except  when  they  are  ftimulated  into  action  by  the  anther-dud, 
and  may  thence  more  eafily  efcape  obfervation.  Nor  do  I  know, 
that  any  one  has  endeavoured  to  detect  thefe  veflels  by  experi- 
ments with  coloured  liquids  applied  along  with  the  male  farina 
on  the  ftigma  for  its  abforption,  or  by  diffccting  the  piftillum  as 
in  its  recent  or  dry  ftate,  or  by  obferving  it  in  a  (late  of  charcoal. 

In  regard  to  quadrupeds,  Dr.  Haighton  has  (hewn  by  a  num- 
ber of  curious  experiments  on  rabbits,  publifhcd  in  the  Philo- 
foph.  Tranfact.  for  the  year  1797,  that  the  male  femen  does 
not  permeate  the  fallopian  tubes,  and  confequeruly  never  arrives 
at  the  female  ova,  either  in  a  liquid  or  aerial  ftate  ;  but  that  it 
is  by  the  ftimulus  of  the  femen  in  the  neck  of  the  uterus  ;  that 
the  veficles  of  the  ovaria  fwell,  and  difcharge  the  material,  which 
has  been  called  an  ovum,  though  it  does  not  po fiefs  a  diftinguifh- 
able  form  ;  and  that  this  is  acquired  and  carried  into  the  uterus 
by  the  periftaltic  motions  of  the  fallopian  tubes,  fome  hours  af- 
ter copulation.  Here  I  fuppofe  it  finds  the  male  femen,  and 
that  thus  the  new  animal  produced  by  the  fecretion  of  the  male 
finds  correfponding  nutriment  and  fituation  in  the  female  in  all 
fexual  progeny.  But  that  no  female  apparatus  is  required  in  the 
production  of  the  buds  of  trees,  or  in  the  adherent  fetus  of  the 
polypus,  or  of  the  coral-infefts. 

In  objection  to  this  theory  of  generation  it  may  be  kid,  if  the 
animalcula  in  femine,  as  feen  by  the  microfcope,  be  all  of  them 
rudiments  of  homunculi,  when  but  one  of  them  can  find  a  nidus, 
what  a  wafte  nature  has  made  of  her  productions  ?  I  do  not  af- 
fert  that  thefe  moving  particles,  vifible  by  the  microfcope,  are 
homunciones  •,  perhaps  they  may  be  the  creatures  of  ftagnation  or 
putridity,  or  perhaps  no  creatures  at  all ;  but  if  they  are  fup- 
pofed  to  be  rudiments  of  homunculi,  or  embryons,  fuch  a  pro- 
fufion  of  them  correfponds  with  the  general  efforts  of  nature  to 
provide  for  the  continuance  of  her  fpecies  of  animals.  Every 
individual  tree  produces  innumerable  feeds,  and  every  individual 
fifh  innumerable  fpawn,  in  fuch  inconceivable  abundance  as 
would  in  a  fhort  fpace  of  time  crowd  the  earth  and  ocean  with 
inhabitants ;  and  thefe  are  much  more  perfect  animals  than  the 
animalcula  in  femine  can  be  fuppofed  to  be,  and  perifh  in  un. 

qounted 


38z  GENERATION.       SECT.  XXXIX.  2. 2. 

counted  millions.  This  argument  only  fliews,  that  the  produc- 
tions of  nature  are  governed  by  general  laws ;  and  that  by  a 
wife  Superfluity  of  provifion  fhe  has  enfured  their  continuance. 

2.  That  the  ennbryon  is  fecreted  or  produced  by  the  male, 
and  not  by  the  conjunction  of  fluids  from  both  male  and  female, 
appears  from  the  analogy  of  vegetable  feeds.  In  the  large  flow- 
ers, as  the  tulip,  there  is  no  fimilarity  of  apparatus  between  the 
anthers  and  the  fligma  :  the  feed  is  produced  according  to  the 
obfervations  of  Spallanzani  long  before  the  flowers  open,  and  in 
confequence  long  before  it  can  be  impregnated,  like  the  egg  in 
the  pullet.  And  after  the  prolific  duft  is  filed  on  the  iligma, 
the  feed  becomes  coagulated  in  one  point  firil,  like  the  cicatricu- 
]a  of  the  impregnated  egg.  See  Botanic  Garden,  Part  I.  addi- 
tional note  38.  Now  in  thefe  fimple  prod ufts  of  nature,  if  the 
female  contributed  to  produce  the  new  embryon  equally  with 
the  male,  there  would  probably  have  been  fome  vifible  fimilarity 
of  parts  for  this  purpofe,  befides  thofe  neceilary  for  the  nidus 
and  fultenance  of  the  new  progeny,  Befides  in  many  flowers 
the  males  are  more  numerous  than  the  females  or  than  the  fepa- 
rate  uterine  cells  in  their  germs,  which  would  (hew,  that  the  of- 
fice of  the  male  was  at  leaft  as  important  as  that  of  the  female ; 
whereas  if  the  male,  befides  producing  the  egg  or  feed,  was  to 
produce  an  equal  part  of  the  embryon,  the  office  of  reproduction 
would  be  unequally  divided  between  them. 

Add  to  this,  that  in  the  moil  fimple  kind  of  vegetable  repro- 
duction, I  mean  the  buds  of  trees,  which  are  the  viviparous 
offspring,  the  leaf  is  evidently  the  parent  of  the  bud,  which  rifes 
in  its  bofom,  according  to  the  observation  of  Linnaeus.  This 
leaf  confifts  of  abforbent  veiTels,  and  pulmonary  ones,  to  obtain 
its  nutriment,  and  to  impregnate  it  with  oxygene.  This  fimple 
piece  of  living  organization  is  alfo  furnifhed  with  a  power  of  re- 
production ;  and  as  the  new  offspring  is  thus  fupporied  adhering 
to  its  father,  it  needs  no  mother  to  fupply  it  with  a  nidus,  and 
nutriment,  and  oxygenation  -9  and  hence  no  female  leaf  has 
exigence. 

I  did  conceive  that  the  veffels  between  the  bud  and  the  leaf 
communicated  or  inofculated  ,  and  that  the  bud  was  thus  ferved 
with  vegetable  blood,  that  is,  with  both  nutriment  and  oxygena- 
tion, till  the  death  of  the  parent-leaf  in  autumn.  And  that  in 
this  refpect  it  differed  from  the  fetus  of  viviparous  animals. 
But,  fmce  the  former  editions  of  this  work  were  published,  I 
have  been  induced  to  change  that  opinion  ;  as  on  differing  the 
bud  of  the  horfe-chefnut,  xfculus  hippocaflanum,  as  mentioned 
below,  no  communication  of  vefTels  between  the  leaf  and  the  bud 
generated  in  its  bofom  could  be  perceived,  fo  that  it  is  more 

probably 


SECT.  XXXIX.  2. 2.        GENERATION.  383 

probably  nourished  by  abforbing  the  fluid,  with  which  it  is  fur- 
rounded,  like  the  fetus  of  animals,  as  ihewn  in  my  work  on 
vegetation,  termed  Phytologia.  Sect.  VII.  i.  2.  Secondly,  I 
conceive  that  then  the  bark-veflels  belonging  to  the  dead  leaf,  and 
in  which  I  fuppofe  a  kind  of  manna  to  have  been  depofited,  be- 
come now  the  placental  veflels,  if  they  may  be  fo  called,  of  the 
oew  bud.  From  the  vernal  fap  thus  produced  of  one  fugar-ma- 
ple-tree  in  New-York  and  in  Pennfylvania,  five  or  fix  pounds  of 
good  fugar  may  be  made  annually  without  deftroying  the  tree. 
Account  of  maple-fugar  by  B.  Rum.  London,  Phiiiips.  (See 
Botanic  Garden,  Part  I.  additional  note  on  vegetable  placenta- 
tion.) 

Thefe  veflels,  when  the  warmth  of  the  vernal  fun  hatches  the 
young  bud,  ferve  it  with  a  faccharine  nutriment,  till  it  acquires 
leaves  of  its  own,  and  (hoots  a  new  fyftem  of  abforbents  down 
the  bark  and  root  of  the  tree,  juft-as  the  farinaceous  or  oily  mat- 
ter in  feeds,  and  the  faccharine  matter  in  fruits,  ferve  their  em- 
bryons  with  nutriment,  till  they  acquire  leaves  and  roots.  This 
analogy  is  as  forcible  in  fo  obfcure  a  fubjedt,  as  it  is  curious,  and 
may  in  large  buds,  as  of  the  horfe-chefnut,  be  aim  >ft  feen  by  the 
naked  eye  ;  if  with  a  penknife  the  remaining  rudiment  of  the 
laft  year's  leaf,  and  of  the  new  bud  in  its  bofom,  be  cut  away 
flice  by  flice.  The  feven  ribs  of  the  lad  year's  leaf  will  be  feen 
to  have  arifen  from  the  pith  in  feven  diftincl;  points  making  a 
curve  ;  and  the  new  bud  to  have  been  produced  in  their  centre, 
and  to  have  pierced  the  alburnum  and  cortex,  and  grown  with- 
out the  afliilance  of  a  mother.  A  fimilar  procefs  may  be  feen 
on  diffeciing  a  tulip-root  in  winter  $  the  leaves,  which  enclofed 
the  laft  year's  flower-ftalk,  were  not  neceffkry  for  the  flower  ; 
but  each  of  thefe  was  the  father  of  a  new  bud,  which  may  be 
now  found  at  its  bafe ;  and  which,  as  it  adheres  to  the  parent, 
required  no  mother. 

This  paternal  offspring  of  vegetables,  I  mean  their  buds  and 
bulbs,  is  attended  with  a  very  curious  circumilance  ;  and  that 
is,  that  they  exactly  referable  their  parents,  as  is  obfervable  in 
grafting  fruit  trees,  and  in  propagating  flower-roots  ;  whereas 
the  feminal  offspring  of  plants,  being  fupplied  with  nutriment 
by  the  mother,  is  liable  to  perpetual  variation.  Thus  alfo  in  the 
vegetable  clafs  dioecia,  where  the  male  flowers  are  produced  on 
one  tree,  and  the  female  ones  on  another  •,  the  buds  of  the  male 
trees  uniformly  produce  either  male  flowers,,  or  other  buds  fimi- 
lar to  themfelves  •,  and  the  buds  of  the  female  trees  produce 
either  female  flowers,  or  other  buds  fimilar  to  themfelves  ; 
whereas  the  feeds  of  thefe  trees  produce  either  male  or  female 
plants.  From  this  analogy  of  the  production  of  vegetable  buds 

without 


3 84  GENERATION.        SECT.  XXXIX.  2.  3, 

without  a  mother,  I  contend  that  the  mother  does  not  contribute 
to  the  formation  of  the  living  ens  in  animal  generation,  but  is 
neceflary  only  for  fupplying  its  nutriment  and  oxygenation. 

There  is  another  vegetable  fac~l  publifhed  by  M.  Koelreuter, 
which  he  calls  "  a  complete  metamorphofis  of  one  natural  fpe- 
cies  of  plants  into  another,"  which  (hews,  that  in  feeds  as  well 
as  in  buds,  the  embryon  proceeds  from  the  male  parent,  though 
the  form  of  the  fubfequent  mature  plant  is  in  part  dependent  on 
the  female.  M.  Koelreuter  impregnated  a  fiigma  of  the  nico- 
tiana ruftica  with  the  farina  of  the  nicotiana  panicuhta,  and  ob- 
tained prolific  feeds  from  it.  With  the  plants  which  fprung 
from  thefe  feeds,  he  repeated  the  experiment,  impregnating  them 
with  the  farina  of  the  nicotiana  paniculata.  As  the  mule  plants 
which  he  thus  produced  were  prolific,  he  continued  to  impreg- 
nate them  for  many  generations  with  the  farina  of  the  nicotiana 
paniculata,  and  they  became  more  and  more  like  the  male  par- 
ent, till  he  at  length  obtained  fix  plants  in  every  refpeft  perfecl- 
]y  fimilar  to  the  nicotiana  paniculata  ;  and  in  no  refpecT:  refem- 
bling  their  female  parent  the  nicotiana  ruftica.  Blumenbach  on 
Generation. 

3.  It  is  probable  that  the  infects,  which  are  faid  to  require  but 
one  impregnation  for  fix  generations,  as  the  aphis  (See  Amenit. 
Academ.)  produce  their  progeny  in  the  manner  above  defcribed, 
that  is,  without  a  mother,  and  not  without  a  father  ;  and  thus 
experience  a  lucina  fine  concubitu.  Thofe  who  have  attended 
to  the  habits  of  the  polypus,  which  is  found  in  the  ftagnant  wa- 
ter of  our  ditches  in  July,  affirm,  that  the  young  ones  branch 
out  from  the  fide  of  the  parent  like  the  buds  of  trees,  and  after 
<\  time  feparate  themfelves  from  them.  This  is  fo  analogous  to 
the  manner  in  which  the  buds  of  trees  appear  to  be  produced, 
that  thefe  polypi  may  be  confidered  as  all  male  animals,  produ- 
cing embryons,  which  require  no  mother  to  fupply  them  with  a 
nidus,  or  with  nutriment,  and  oxygenation. 

This  lateral  or  lineal  generation  of  plants,  not  only  obtains  in 
the  buds  of  trees,  which  continue  to  adhere  to  them,  but  is 
beautifully  feen  in  the  wires  of  knots-grafs,  polygonum  aviculare, 
and  in  thofe  of  ftrawberries,  fragaria  vefca.  In  thefe  an  elonga- 
ted creeping  bud  is  protruded,  and,  where  it  touches  the  ground, 
takes  root,  and  produces  a  new  plant  derived  from  its  father, 
from  which  it  acquires  both  nutriment  and  oxygenation  ;  and 
in  confequence  needs  no  maternal  apparatus  for  thefe  purpofes. 
In  viviparous  flowers,  as  thofe  of  allium  magicum,  and  polygo- 
num viviparum,  the  anthers  and  the  ftigmas  become  effete  and 
perifh  j  and  the  lateral  or  paternal  offspring  fucceed,  inftead  of 

feeds, 


SECT.  XXXIX.  3.  i.      GENERATION,  385 

feeds  which  adhere  till  they  are  fufficiently  mature,  and  then  fall 
upon  the  ground,  and  take  root  like  other  bulbs. 

The  lateral  produ6tion  of  plants  by  wires,  while  each  new 
plant  is  thus  chained  to  its  parent,  and  continues  to  put  forth 
another  and  another,  as  the  wire  creeps  onward  on  the  ground, 
is  exactly  refembled  by  the  tape- worm,  or  taenia,  fo  often  found 
in  the  bowels,  ftretching  itfelf  in  a  chain  quite  from  the  ftom- 
ach  to  the  re&um.  Linnxus  aflerts,  "  that  it  grows  old  at  one 
extremity,  while  it  continues  to  gerferate  young  ones  at  the  oth- 
er, proceeding  ad  infinitum,  like  a  root  of  grafs.  The  feparate 
joints  are  called  gourd- worms,  and  propagate  new  joints  like  the 
parent  without  end,  each  joint  being  furmftied  with  its  proper 
mouth,  and  organs  of  digeftjon."  Syftema  natune.  Vermes 
tenia.  In  this  animal  there  evidently  appears  a  power  of  repro- 
du£lion  without  any  maternal  apparatus  for  the  purpofe  of  fup- 
plying  nutriment  and  oxygenation  to  the  embryon,  as  it  remains 
attached  to  its  father  till  its  maturity.  The  volvox  globator, 
which  is  a  tranfparent  animal,  is  faid  by  Linnaeus  to  bear  within 
it  fons  and  grand-fons  to  the  fifth  generation.  Thefe  are  prob- 
ably living  fetufes,  produced  by  the  father,  of  different  degrees 
of  maturity,  to  be  detruded  at  different  periods  of  time,  like  the 
unimpregnated  eggs  of  various  fizes,  which  are  found  in  poul- 
try ;  and  as  they  are  produced  without  any  known  copulation, 
contribute  to  evince,  that  the  living  embryon  in  other  orders  of 
animals  is  formed  by  the  male  parent,  and  not  by  the  mother,  as 
one  parent  has  the  power  to  produce  it. 

This  idea  of  the  reproduction  of  animals  from  a  fingle  living 
filament  of  their  fathers,  appears  to  have  been  fhadowed  or  al- 
legorized in  the  curious  account  in  facred  writ  of  the  formation 
of  Eve  from  a  rib  of  Adam. 

From  all  thefe  analogies  I  conclude,  that  the  embryon  is  pro- 
duced folely  by  the  male,  and  that  the  female  fupplies  it  with  a 
proper  nidus,  with  fuftenance,  and  with  oxygenation  ;  and  that 
the  idea  of  the  femen  of  the  male  conflituting  only  a  flimulus  to 
the  egg  of  the  female,  exciting  it  into  life,  (as  held  by  fome  phi- 
lofophers)  has  no  fupportfrom  experiment  or  analogy. 

III.  I.  Many  ingenious  phiiofophers  have  found  fo  great 
difficulty  in  conceiving  the  manner  of  the  reproduction  of  ani- 
mals, that  they  have  fuppofed  all  the  numerous  progeny  to  have 
exifted  in  miniature  in  the  animal  originally  created  ;  and  that 
theie  infinitely  minute  forms  are  only  evolved  or  diftended  a& 
the  embryon  increafes  in  the  womb.  This  idea,  befides  its  being 
unfupported  by  any  analogy  we  are  acquainted  with,  afcribes  a 
greater  tenuity  to  organized  matter,  than  we  can  readily  admit; 
as  thefe  included  embryons  are  fuppofed  each  of  them  to  confift 

VOL.  I.  B  B  b  of 


386  GENERATION.         SECT.  XXXIX.  3. 2. 

of  the  various  and  complicate  parts  of  animal  bodies :  they  muft 
poflefs  a  much  greater  degree  of  minutenefs,  than  that  which 
was  afcribed  to  the  devils  that  tempted  St.  Anthony  •,  of  whom 
20,000  were  faid  to  have  been  able  to  dance  a  faraband  on  the 
point  of  the  fined  needle  without  incommoding  each  other. 

2.  Others  have  fuppofed,  that  all  the  parts  of  the  embryon  are 
formed  in  the  male,  previous  to  its  being  depofited  in  the  egg 
or  uterus  ;  and  that  it  is  thep  only  to  have  its  parts  evolved  or  dif- 
tended  as  mentioned  above  ;>  but  this  is  only  to  get  rid  of  one 
difficulty  by  propofing  another  equally  incomprehenfible :  they 
found  it  difficult  to  conceive,  how  the  embryon  could  be  formed 
in  the  uterus  or  egg,  and  therefore  wiihed  it  to  be  formed  before 
it  came  thither.  In  anfwer  to  both  thefe  doftrines  it  may  be  ob- 
ferved,  ift,  that  fome  animals,  as  the  crab-fifh,  can  reproduce 
a  whole  limb,  as  a  leg  which  has  been  broken  ofF^  others,  as 
worms  and  fnails,  can  reproduce  a  head,  or  a  tail,  when  either 
of  them  has  been  cut  away  ;  and  that  hence  in  thefe  animals  at 
leaft  a  part  can  be  formed  anew,  which  cannot  be  fuppofed  to 
have  exifted  previoufly  in  miniature. 

Secondly,  there  are  new  parts  or  new  veflels  produced  in 
many  difeafes,  as  on  the  cornea  of  the  eye  in  ophthalmy,  in  wens 
and  cancers,  which  cannot  be  fuppofed  to  have  had  a  prototype 
or  original  miniature  in  the  embryon. 

Thirdly,  how  could  mule-animals  be  produced,  which  partake 
of  the  forms  of  both  the  parents,  if  the  original  embryon  was  a 
miniature  exifting  in  the  femen  of  the  male  parent  ?  if  an  em- 
bryon of  the  male  afs  was  only  expanded,  no  refemblance  to  the 
mare  could  exift  in  the  mule. 

This  miftaken  idea  of  the  extenfions  of  parts  feem  to  have  had 
its  rife  from  the  mature  man  refembling  the  general  form  of  the 
fetus  ;  and  from  thence  it  was  believed,  that  the  parts  of  the 
fetus  were  diftended  into  the  man ;  whereas  they  have  increafed 
100  times  in  weight,  as  well  as  100  times  in  fize  ;  now  no  one 
will  call  the  additional  ninety-nine  parts  a  diftention  of  the 
original  one  in  refpeft  to  weight.  Thus  the  uterus  during 
pregnancy  is  greatly  enlarged  in  thicknefs  and  folidity  as  well  as 
in  capacity,  and  hence  muft  have  acquired  this  additional  (ize 
by  accretion  of  new  parts,  not  by  an  exrenfion  of  the  old  ones  ; 
the  familiar  a£t  of  blowing  up  the  bladder  of  an  animal  recently 
flaughtered  has  led  our  imaginations  to  apply  this  idea  of  dif- 
tention to  the  increafe  of  fize  from  natural  growth  ;  which 
however  muft  be  owing  to  the  appofition  of  new  parts  ;  as  it  is 
evinced  from  the  increafe  of  weight  along  with  the  increafe  of 
dimenfion  •,  and  is  even  vifible  to  our  eyes  in  the  elongation  of 
our  hair  from  the  colour  of  its  ends  j  or  when  it  has  been  died 

on 


.  XXXIX.  3. 3.        GENERATION.  387 

on  the  head  ;  and  in  the  growth  of  our  nails  from  the  fpecks 
fometimes  obfervable  on  them  ;  and  in  the  increafe  of  the  white 
crefcent  at  the  roots,  and  in  the  growth  of  new  flefh  in  wounds, 
which  confifls  of  new  nerves  as  well  as  of  new  blood- veflels. 

3.  Laftly,  Mr.  Buffon  has  with  great  ingenuity  imagined  the 
exiftence  of  certain  organic  particles,  which  are  fuppofed  to  oe 
partly  alive,  and  partly  mechanic  fprings.  The  latter  of  thefe 
were  difcovered  by  Mr,  Needham  in  the  milt  or  male  organ  of  a 
fpecies  of  cuttle  fi(h,  called  calmar  ;  the  former,  or  living  animal- 
cula,  are  found  in  both  male  and  female  fecretions,in  the  infufions 
of  feeds,  as  of  pepper,  in  the  jelly  of  roafted  veal,  and  in  all  other 
animal  and  vegetable  fubftances.  Thefe  organic  particles  he 
fuppofes  to  exift  in  the  fpermatic  fluid  of  both  fexes,  and  that 
they  are  derived  thither  from  every  part  of  the  body,  and  muft 
therefore  refemble,  as  he  fuppofes,  the  parts  from  whence  they 
are  derived.  Thefe  organic  particles  he  believes  to  be  in  con- 
ftant  aftivity,  till  they  become  mixed  in  the  womb,  and  then 
they  inftantly  join  and  produce  an  embryon  or  fetus  fimilar  to 
the  two  parents. 

Many  objections  might  be  adduced  to  this  ingenious  theory  ; 
I  (hall  only  mention  two.  Firft,  that  it  is  analogous  to  no 
known  animal  laws.  And  fecondly,  that  as  thefe  fluids,  replete 
with  organic  particles  derived  both  from  the  male  and  female 
organs,  are  fuppofed  to  be  fimilar  ;  there  is  no  reafon  why  the 
mother  (hould  not  produce  a  female  embryon  without  the  af- 
fiftance  of  the  male,  and  realize  the  lucina  fine  concubitu.  See 
No  8  and  9  of  this  feclion,  and  Sea.  XXXVII.  3. 

IV.  i.  I  conceive  the  primordium,  or  rudiment  of  the  em- 
bryon, as  fecreted  from  the  blood  of  the  parent,  to  confift  of  a 
fimple  living  filament  as  a  mufcular  fibre ;  which  1  fuppofe  to 
be  an  extremity  of  a  nerve  of  locomotion,  as  a  fibre  of  the  reti- 
na is  an  extremity  of  a  nerve  of  fenfation  ;  as  for  inftance  one 
of  the  fibrils,  which  compofe  the  mouth  of  an  abforbent  veflel  •, 
I  fuppofe  this  living  filament,of  whatever  form  it  may  be,  wheth- 
er fphcre,  cube,  or  cylinder,  to  be  endued  with  the  capability  of 
being  excited  into  aclion  by  certain  kinds  of  (limulus.  By  the 
ilimulus  of  the  furrounding  fluid,  in  which  it  is  received  from 
the  male,  it  may  bend  into  a  ring  :  and  thus  form  the  beginning 
of  a  tube.  Such  moving  filaments,  and  fuch  rings,  are  defcribed 
by  thofe,  who  have  attended  to  microfcopic  animalcula.  This 
living  ring  may  now  embrace  or  abforb  a  nutritive  particle  of 
the  fluid,  in  which  it  fwims  ;  and  by  drawing  it  into  its  pores,  or 
joining  it  by  comprefiion  to  its  extremities,  may  increafe  its  own 
length  or  craflitude  ;  and  by  degrees  the  living  ring  may  become 
a  living  tube. 

2.  With 


3  8  8  GENER  ATION.         SECT.  XXXIX.  4.  2. 

2.  With  this  new  organization,  or  accretion  of  parts,  new 
kinds  of  irritability  may  commence ;  for  fo  long  as  there  was 
but  one  living  organ,  it  could  only  be  fuppofed  to  poflefs  irrita- 
bility ;  fince  fenfibility  may  be  conceived  to  be  an  extenfion  of 
the  effeft  of  irritability  over  the  reft  of  the  fyftem.  Thefe  new 
kinds  of  irritability  and  of  fenfibiiity  in  confequence  of  new  or- 
ganization, appear  from  variety  of  facts  in  the  more  mature  ani- 
mal ;  thus  the  formation  of  the  teftes,  and  confequent  fecretion 
of  the  femen,  occafion  the  paflion  of  luft  ;  the  lungs  muft  be 
previoufly  formed  before  their  exertions  to  obtain  frefli  air  can 
exift  •,  the  throat  or  cefophagus  muft  be  formed  previous  to  the 
fenfation  or  appetites  of  hunger  and  thirft  ;  one  of  which  feems 
to  refide  at  the  upper  end,  and  the  other  at  the  lower  end  of 
that  canal. 

Thus  alfo  the  glans  penis,  when  it  is  diftended  with  blood, 
acquires  anew  fenfibility,  and  a  new  appetency.  The  fame  oc- 
curs to  the  nipples  of  the  breads  of  female  animals  ;  when  they 
are  diftended  with  blood,  they  acquire  the  new  appetency  of 
giving  milk.  So  inflamed  tendons  and  membranes,  and  even 
bones,  acquire  new  fenfations  ;  and  the  parts  of  mutilated  ani- 
mals, as  of  wounded  fnails,  and  polypi,  and  crabs,  are  reprodu- 
ced ;  and  at  the  fame  time  acquire  fenfations  adapted  to  their 
(ituations.  Thus  when  the  head  of  a  fnail  is  reproduced  after 
decollation  with  a  (harp  razor,  thofe  curious  telefcopic  eyes  are 
alfo  reproduced,  and  acquire  their  fenfibility  to  light,  as  well 
as  their  adapted  mufcles  for  retraction  on  the  approach  of 
injury. 

With  every  new  change,  therefore,  of  organic  form,  or  addi- 
tion of  organic  parts,  I  fuppofe  a  new  kind  of  irritability  or  of 
fenfibility  to  be  produced  ;  fuch  varieties  of  irritability  or  of  fen- 
fibility exift  in  our  adult  ftate  in  the  glands ;  every  one  of  which 
is  furnifhed  with  an  irritability,  or  a  tafte,  or  appetency,  and  a 
confequent  mode  of  a£Hon  peculiar  to  itfelf. 

In  this  manner  I  conceive  the  veflels  of  the  jaws  to  produce 
the  teeth,  thofe  of  the  fingers  to  produce  the  nails,  thofe  of  the 
fkin  to  produce  the  hair  ;  in  the  fame  manner  as  afterwards 
about  the  age  of  puberty  the  beard  and  other  great  changes  in 
the  form  of  the  body,  and  difpofition  of  the  mind,  are  produced 
in  confequence  of  the  new  fecretion  of  femen  ;  for  if  the  animal 
is  deprived  of  this  fecretion  thofe  changes  do  not  take  place, 
Thefe  changes  I  conceive  to  be  formed  not  by  elongation  or  dif- 
tention  of  primeval  ftamina,  but  by  appofition  of  parts ;  as  the 
mature  crab-fifth,  when  deprived  of  a  limb,  in  a  certain  fpace  of 
time  has  power  to  regenerate  it ;  and  the  tadpole  puts  forth  its 
feet  long  after  its  exclufion  from  the  fpawn  j  and  the  caterpil- 
lar 


SECT.  XXXIX.  4.  2.        GENERATION.  389 

lar  in  changing  into  a  butterfly  acquires  a  new  form,  with  new 
powers,  new  fenfations,  and  new  defires. 

The  natural  hiftory  of  butterflies,  and  moths,  and  beetles, 
and  gnats,  is  full  of  curioflty  ;  fome  of  them  pafs  many  months* 
and  others  even  years,  in  their  caterpillar  or  grub  (late  ;  they 
then  reft  many  weeks  without  food,  fufpended  in  the  air,  buried 
in  the  earth,  or  fubmerfed  in  water  :  and  change  themfelves 
during  this  time  into  an  animal  apparently  of  a  different  nature  ; 
the  (lomachs  of  fome  of  them,  which  before  digefted  vegetable 
leaves  or  roots,  now  only  digeft  honey  ;  they  have  acquired 
wings  for  the  purpofe  of  feeking  this  new  food,  and  a  long  pro- 
bofcis  to  collect  it  from  flowers,  and  I  fuppofe  a  fenfe  of  fmell  to 
deteft  the  fecret  places  in  flowers,  where  it  is  formed.  The 
moths,  which  fly  by  night,  have  a  much  longer  probofcis  rolled 
up  under  their  chins  like  a  watch  fpring  ;  which  they  extend  to 
collet  the  honey  from  flowers  in  their  fleeping  ftate ;  when  they 
are  clofed,  and  the  nectaries  in  confequence  more  difficult  to  be 
plundered.  The  beetle  kind  are  furniftied  with  an  external 
covering  of  a  hard  material  to  their  wings,  that  they  may  occa- 
iionally  again  make  holes  in  the  earth,  in  which  they  paffed  the 
former  ftate  of  their  exiftence. 

But  what  moft  of  all  diftinguifhes  thefe  new  animals  is,  that 
they  are  now  furnifhed  with  the  powers  of  reproduction  ;  and 
that  they  now  differ  from  each  other  in  fex,  which  does  not  ap- 
pear in  their  caterpillar  or  grub  ftate.  In  fome  of  them  the 
change  from  a  caterpillar  into  a  butterfly  or  moth  feems  to  be 
accomplimed  for  the  fole  purpofe  of  their  propagation  ;  (ince 
they  immediately  die  after  this  is  iiniftied,  and  take  no  food  in 
the  interim,  as  the  filk-worm  in  this  climates  ;  though  it  is  pofli- 
blc  it  might  take  honey  as  food,  if  it  was  prefented  to  it.  For 
in  general  it  would  feem,  that  food  of  a  more  ftimulating  kind, 
the  honey  of  vegetables  inftead  of  their  leaves,  was  neceffary  for 
the  purpofe  of  the  feminal  reproduction  of  thefe  animals,  exactly 
fimilar  to  what  happens  in  vegetables  ;  in  thefe  the  juices  of  the 
earth  are  fufficient  for  their  purpofe  of  reproduction  by  buds  or 
bulbs  ;  in  which  the  new  plant  feems  to  be  formed  by  irritative 
motions,  like  the  growth  of  their  other  parts,  as  their  leaves  or 
roots  j  but  for  the  purpofe  of  feminal  or  amatorial  reprodu&ion, 
\vhere  fenfation  is  required,  a  more  ftimulating  food  becomes 
necefTary  for  the  anther  and  ftigma  ;  and  this  food  is  honey  ; 
as  explained  in  Se£t.  XIII.  on  Vegetable  Animation. 

The  gnat  and  the  tadpole  refemble  each  other  in  their  change 
from  natant  animals  with  gills  into  aerial  animals  with  Jungs  ; 
and  in  their  change  of  the  element  in  which  they  live;  and  proba- 
bly of  the  food,  with  which  they  are  fupported  ;  and  laftly,  with 

their 


390  GENERATION.        SECT.  XXXIX.  4.  3« 

their  acquiring  in  their  new  flate  the  difference  of  fex,  and  the 
organs  of  feminal  or  amatorial  reprodu&ion.  While  the  poly- 
pus, who  is  their  companion  in  their  former  flate  of  life,  not 
being  allowed  to  change  his  form  and  element,  can  only  propa- 
gate like  vegetable  buds  by  the  fame  kind  of  irritative  motions, 
which  produces  the  growth  of  his  own  body,  without  the  femi- 
nal or  amatorial  propagation,  which  requires  fenfation  ;  and 
which  in  gnats  and  tadpoles  feems  to  require  a  change  both  of 
food  and  refpiration. 

From  hence  I  conclude,  that  with  the  acquifition  of  new  parts, 
new  fenfations,  and  new  defires,  as  well  as  new  powers,  are 
produced  ;  and  this  by  accretion  to  the  old  ones,  and  not  by  dif- 
tention  of  them.  And  finally,  that  the  moft  eiTential  parts  of 
the  fyftem,  as  the  brain  for  the  purpofe  of  diftributing  the  pow- 
er of  life,  and  the  placenta  for  the  purpofe  of  oxygenating  the 
blood,  and  the  additional  abforbent  veiTels  for  the  purpofe  of  ac- 
quiring aliment,  are  firil  formed  by  the  irritations  above  men- 
tioned, and  by  the  pleafurable  fenfations  attending  thofe  irrita- 
tions, and  by  the  exertions  in  confequence  of  painful  fenfations, 
fimilar  to  thofe  of  hunger  and  fuffbcation  After  thefe  an  ap- 
paratus of  limbs  for  future  ufes,  or  for  the  purpofe  of  moving 
the  body  in  its  prefent  natant  flate,  and  of  lungs  for  future  ref- 
piration, and  of  teftes  for  future  reprodudlion,  are  formed  by  the 
irritations  and  fenfations,  and  confequent  exertions  of  the  parts 
previoufly  exifting^  and  to  which  the  new  parts  are  to  be  attached. 

3.  In  confirmation  of  thefe  ideas  it  may  be  obferved,  that  all 
the  parts  of  the  body  endeavour  to  grow,  or  to  make  additional 
parts  to  themfelves  throughout  our  lives  ;  but  are  reftrained  by 
the  parts  immediately  containing  them  ;  thus,  if  the  fkin  be  taken 
away,  the  flefhy  parts  beneath  foon  fhoot  out  new  granulations, 
called  by  the  vulgar  proud  flefh.  If  the  periofteum  be  removed, 
a  fimilar  growth  commences  from  the  bone.  Now  in  the  cafe 
of  the  imperfect  embryon,  the  containing  or  confining  parts  are 
not  yet  fuppofed  to  be  formed,  and  hence  there  is  nothing  to  re- 
ftram  its  growth. 

4  By  the  parts  of  the  embryon  being  thus  produced  by  new 
appofitions,  many  phenomena  both  of  animal  and  vegetable  pro- 
duftions  receive  an  eafier  explanation  ;  fuch  as  that  many  fetuf- 
es  are  deficient  at  the  extremities,  as  in  a  finger  or  a  toe,  or  in 
the  end  of  the  tongue,  or  in  what  is  called  a  hare-lip  with  de- 
ficiency of  the  palate.  For  if  there  fhould  be  a  deficiency  in 
the  quantity  of  the  firft  nutritive  particles  laid  up  in  the  egg  for 
the  reception  of  the  firft  living  filament,  the  extreme  parts,  as 
being  laft  formed,  muft  fhew  this  deficiency  by  their  being  im- 
perfeft. 

This 


SECT.  XXXIX.  4. 5.         GENERATION.  391 

This  idea  of  the  growth  of  the  embryon  accords  alfo  with  the 
production  of  fome  monftrous  births,  which  confift  of  aduplica- 
ture  of  the  limbs,  as  chickens  with  four  legs  ;  which  could  not 
occur,  if  the  fetus  was  formed  by  the  diftention  of  an  original 
ftamen,  or  miniature.  For  if  there  fhould  be  a  fuperfluity  of 
the  firft  nutritive  particles  laid  up  in  the  egg  for  the  firft  living 
filament ;  it  is  eafy  to  conceive,  that  a  duplicature  of  fome  parts 
may  be  formed.  And  that  fuch  fuperfluous  nouriihment  fome- 
times  exifts,  is  evinced  by  the  double  yolk  in  fome  eggs,  which 
I  fuppofe  were  thus  formed  previous  to  their  impregnation  by  the 
exuberant  nutriment  of  the  hen. 

This  idea  is  confirmed  by  the  analogy  of  the  monfters  in  the 
vegetable  world  alfo ;  in  which  a  duplicate  or  triplicate  produc- 
tion of  various  parts  of  the  flower  is  obfervable,  as  a  triple  necla- 
ry  in  fome  columbines,  and  a  triple  petal  in  fome  primrofes ; 
and  which  are  fuppofed  to  be  produced  by  abundant  nourifh- 
ment. 

5.  If  the  embryon  be  received  into  a  fluid,  the  ftimulus  of 
which  is  different  in  fome  degree  from  the  natural,  as  in  the 
production  of  mule  animals,  the  new  irritabilities  or  fenfibilities 
acquired  by  the  increafing  or  growing  organized  parts  may  differ,, 
and  thence  produce  parts  not  fimilar  to  the  father,  but  of  a  kind 
belonging  in  part  to  the  mother ;  and  thus,  though  the  original 
ftamen  or  living  ens  was  derived  totally  from  the  father,  yet  new- 
irritabilities  or  fenfibilities  being  excited,  a  change  of  form  cor- 
refponding  with  them  will  be  produced.  Nor  could  the  pro- 
dudlion  of  mules  exift,  if  the  ftamen  or  miniature  of  all  the 
parts  of  the  embryon  is  previoufly  formed  in  the  male  femen, 
and  is  only  diftended  by  nourifhment  in  the  female  uterus. 
Whereas  this  difficulty  ceafes,  if  the  embryon  be  fuppofed  to 
confift  of  a  living  filament,  which  acquires  or  makes  new  parts 
with  new  irritabilities,  as  it  advances  its  growth. 

The  form,  folidity,  and  colour,  of  the  particles  of  nutriment 
hid  up  for  the  reception  of  the  firft  living  filament,  as  well  as 
their  peculiar  kind  of  ftimulus,  may  contribute  to  produce  a  dif- 
ference in  the  form,  folidity,  and  colour  of  the  fetus,  fo  as  to  re- 
ferable the  mother,  as  it  advances  in  life.  This  alfo  may  ef- 
pecially  happen  during  the  firft  ftate  of  the  exigence  of  the 
embryon,  before  it  has  acquired  organs,  which  can  change  thefe 
firft  nutritive  particles,  as  explained  No.  5.  2.  of  this  Sedion* 
And  as  thefe  nutritive  particles  are  fuppofed  to  be  fimilar  to 
thofe.  which  are  formed  for  her  own  nutrition,  it  follows  that 
the  fetus  fhouid  fo  far  refemble  the  mother. 

This  explains,  why  hereditary  difeafes  may  be  derived  either 
from  the  male  or  female  parent,  as  well  as  the  peculiar  form  of 

either 


GENERATION.        SECT.  XXXIX.  4. 6. 

either  of  their  bodies.  Some  of  thefe  hereditary  difeafes  are 
(imply  owing  to  a  deficient  activity  of  a  part  of  the  fyftem,  as  of 
the  abforbent  veffels,  which  open  into  the  cells  or  cavities  of  the 
body,  and  thus  occafion  dropfies.  Others  are  at  the  fame  time 
owing  to  an  increafe  of  fenfation,  as  in  fcrofula  and  confump- 
tion  •,  in  thefe  the  obftrudion  of  the  fluids  is  firft  caufed  by  the 
inirritability  of  the  veflels,  and  the  inflammation  and  ulcers 
which  fucceed,  are  caufed  by  the  confequent  increafe  of  fenfa- 
tion in  the  obftruded  part.  Other  hereditary  difeafes,  as  the 
epilepfy,  and  other  convulfions,  confift  in  too  great  voluntary 
exertions  in  confequence  of  difagreeable  fenfation  in  fome  par- 
ticular difeafed  part.  Now  as  the  pains,  which  occafion  thefe 
convulfions,  are  owing  to  defect  of  the  action  of  the  difeafed 
part,  as  (hewn  in  Seel:.  XXXIV.  it  is  plain,  that  all  thefe  heredi- 
tary difeafes  may  have  their  origin  either  from  defective  irrita- 
bility derived  from  the  father,  or  from  deficiency  of  the  ftimu- 
lus  of  the  nutriment  derived  from  the  mother.  In  either  cafe 
the  effect  would  be  fimilar ;  as  a  fcrofulus  race  is  frequently 
produced  among  the  poor  from  the  deficient  (limulus  of  bad 
diet,  or  of  hunger  ;  and  among  the  rich,  by  a  deficient  irritabili- 
ty from  their  having  been  long  accuftomed  to  too  great  ftimulus, 
as  of  vinous  fpirit. 

6,  From  this  account  of  reproduction  it  appears,  that  all  ani- 
mals have  a  fimilar  origin,  viz  from  a  fingle  living  filament ; 
and  that  the  difference  of  their  forms  and  qualities  has  arifen 
only  from  the  different  irritabilities  and  fenfibilities,  or  volunta- 
rities,  or  aflbciabilities,  of  this  original  living  filament  ;  and  per- 
haps in  fome  degree  from  the  different  forms  of  the  particles  of 
the  fluids,  by  which  it  has  been  at  firft  Simulated  into  activity* 
And  that  from  hence,  as  Linngeus  has  conjectured  in  refpect  to 
the  vegetable  world,  it  is  not  impoffible,  but  the  great  variety  of 
fpecies  of  animals,  which  now  tenant  the  earth,  may  have  had 
their  origin  from  the  mixture  of  a  few  natural  orders.  And 
that  thofe  animal  and  vegetable  mules,  which  could  continue 
their  fpecies,  have  done  fo,  and  conftitute  the  numerous  families 
of  animals,  and  vegetables  which  now  exifl  •,  and  that  thofe 
mules,  whicfy  were  produced  with  imperfedt  organs  of  genera- 
tion, perifned  without  reproduction,  according  to  the  obferva- 
tion  of  Ariftotle  ;  and  are  the  animals,  which  we  now  call  mules. 
See  Botanic  Garden,  Part  II.  Note  on  Dianthus. 

Such  a  promifcuous  intercourfe  of  animals  is  faid  to  exift  at 
this  day  in  New  South  Wales  by  Captain  Hunter,  And  that 
not  only  amongft  the  quadrupeds  and  birds  of  different  kinds, 
but  even  amongft  the  fifh,  and,  as  he  believes,  amongft  the 
vegetables.  He  fpeaks  of  an  animal  between  the  opoffum  and 

the 


SECT.  XXXIX.  4.  7.         GENERATION. 

the  kangaroo,  from  the  fize  of  a  fheep  to  that  of  a  rat.  Many 
fifh  feemed  to  partake  of  the  (hark  ;  fome  with  a  fkait's  head 
and  fhoulders,  and  the  hind  part  of  a  (hark  ;  others  with  a 
fhark's  head  and  the  body  of  a  mullet  j  and  fome  with  a  fhark's 
head  and  the  flat  body  of  a  (ting-ray.  Many  birds  partake  of 
the  parrot ;  fome  have  the  head,  neck,  and  bill  of  a  parrot,  with 
long  (Iraight  feet  and  legs  ;  others  with  legs  and  feet  of  a  par- 
rot, with  head  and  neck  of  a  fea-gull.  Voyage  to  South  Wales 
by  Captain  John  Hunter,  p.  68. 

7.  All  animals  therefore,  I  contend,  have  a  fimilar  caufe  of 
their  organization,  originating  from  a  (ingle  living  filament,  en- 
dued indeed  with  different  kinds  of  irritabilities  and  fenfibilities, 
or  of  animal  appetencies  ;  which  exift  in  every  gland,  and  in 
every  moving  organ  of  the  body,  and  are  as  efTcntial  to  living 
organization  as  chemical  affinities  are  to  certain  combinations  of 
inanimate    matter. 

If  I  might  be  indulged  to  make  a  fimile  in  a  philofophical 
work,  I  (hould  fay,  that  the  animal  appetencies,  are  not  only  per- 
haps lefs  numerous  originally  than  the  chemical  affinities  j  but 
that  like  chefe  latter,  they  change  with  every  new  combination  ; 
thus  vital  air  and  azote,  when  combined,  produce  nitrous  acid  ; 
which  now  acquires  the  property  of  diflblving  filver ;  fo  with 
every  new  additional  part  to  the  embryon,  as  of  the  throat  or 
lungs,  I  fuppofe  a  new  animal  appetency  to  be  produced. 

In  this  early  formation  of  the  embryon  from  the  irritabilities, 
fenfibilities,  and  afibciabilities,  and  confequent  appetencies,  the 
faculty  of  volition  can  fcarcely  be  fuppofed  to  have  had  its  birth. 
For  about  what  can  the  fetus  deliberate  when  it  has  no  choice  of 
objects  ?  But  in  the  more  advanced  ftate  of  the  fetus,  it  evident- 
ly pofleflfes  volition  ;  as  it  frequently  changes  its  attitude,  though 
it  feems  to  deep  the  greateft  part  of  its  time  ;  and  afterwards 
the  power  of  volition  contributes  to  change  or  alter  many  parts 
of  the  body  during  its  growth  to  manhood,  by  our  early  modes 
of  exertion  in  the  various  departments  of  life.  All  thefe  facul- 
ties then  conftitute  the  vis  fabricatrix,  and  the  vis  confervatrix, 
as  well  as  the  vis  medicatrix  of  nature,  fo  much  fpoken  of,  but 
fo  little  underftood  by  philofophers. 

8.  When  we  revolve  in  our  minds,  firft,  the  great  changes, 
which  we  fee  naturally  produced  in  animals  after  their  nativity, 
as  in  the  production   of  the  butterfly  with  painted  wings  from, 
the  crawling  caterpillar  ;  or  of  the  refpiring  frog  from  the  fub- 
natant  tadpole  ;  from  the  feminine  boy  to  the  bearded  man,  and 
from  the  infant    girl  to    the   laclefcent   woman  ;  both  which 
changes  may  be  prevented  by  certain  mutilations  of  the  glands 
neceffary  to  reproduction. 

VOL.  I.  C  c  c  Secondly, 


394  GENERATION.        SECT.  XXXIX.  4.  8. 

Secondly,  when  we  think  over  the  great  changes  introduced  in- 
to various  animals  by  artificial  or  acciden  talc  ultivation, as  inhorfes 
which  we  have  exercifed  for  the  different  purpofes  of  ftrength  or 
fwiftnefs,  in  carrying  burthens  or  in  running  races  ;  or  in  dogs, 
which  have  been  cultivated  for  ftrength  and  courage,  as  the  bull- 
dog ;  or  for    acutenefs  of  his  fenfe  of  frnell>  as  the  hound  and 
fpaniel  -,  or  for  the  fwiftnefs  of  his  foot,  as  the  greyhound  ;  or  for 
his  fwimming  in  the  water,  or  for  drawing  fnow-fledges,  as  the 
rough-haired   dogs    of  the  north  ;  or  laftly,  as  a  play  dog  for 
children,  as  the  lap-dog  ;  with  the  changes  of  the  forms  of  the 
cattle,  which  have  been  domefticated  from  the  greateft  antiquity, 
as  camels,  and  fheep  ;  which  have  undergone  fo  total  a  transfor- 
mation, that  we  are  now  ignorant  from  what  fpecies  of  wild  an- 
imals they  had  their  origin.     Add  to'thefe  the  great  changes  of 
fhape  and  colour,  which  we  daily    fee  produced  in  fmaller  ani- 
mals from  our  domefiication  of  them,  as  rabbits,  or  pigeons  ;  or 
from  the    difference  of  climates  and  even  of  feafons  ;  thus    the 
iheep  of  warm  climates  are  covered  with  hair  inflead  of  wool  ; 
and  the  hares  and  partridges  of  the  latitudes,  which  are  long  buri- 
ed in  fnow,  become  white  during  the  winter  months  ;  add  to 
thefe  the  various  changes  produced  in  the  forms  of  mankind,  by 
their  early  modes  of  exertion  ,  or    by  the  difeafes  occasioned  by 
their  habits  of  life  ;  both  of  which  became  hereditary,  and  that 
through  many  generations.     Thofe  who  labour  at  the  anvil,  the 
oar,  or  the  loom,  as  well  as  thofe  who  carry  fedan-chairs,  or  who 
have  been  educated  to   dance  upon  the  rope,  are  diftinguiftiable 
by  the  fhape  of  their  limbs  ;  and  the  difeafes  occafioned  by  in- 
toxication deform  the  countenance  with  leprous  eruptions,  or  the 
body  with  tumid  vifcera,  or  the  joints  with  knots  and  diftortions. 

Thirdly,  when  we  enumerate  the  great  changes  produced  in 
the  fpecies  of  animals  before  their  nativity  ;  thefe  are  fuch  as 
refemble  the  form  or  colour  of  their  parents,  which  have  been 
altered  by  the  cultivation  or  accidents  above  related,  and  are 
thus  continued  to  their  pofterity.  Or  they  are  changes  produ- 
ced by  the  mixture  of  fpecies  as  in  mules  ;  or  changes  produced 
probably  by  the  exuberance  of  nourifhment  fupplied  to  the  fe- 
tus, as  in  monftrous  births  with  additional  limbs  ;  many  of  thefe 
enormities  of  fhape  are  propagated,  and  continued  as  a  variety 
at  leaft,  if  not  as  a  new  fpecies  of  animal.  I  have  feen  a  breed 
of  cats  with >  an  additional  claw  on  every  foot: ;  of  poultry  alfo 
with  an  additional  claw,  and  with  wings  to  their  feet  ;  and  of 
others  without  rumps.  Mr.  Buffon  mentions  a  breed  Nof  dogs 
without  tails,  which  are  common  at  Rome  and  at  Naples,  which 
he  fuppofes  to  have  been  produced  by  a  cuftom  long  eflablifhed 
of  cutting  their  tails  clofe  cfF.  There  are  many  kinds  of  pigeons, 

admired 


SECT.  XXXIX.  4.  8.         GENERATION.  395 

admired  for  their  peculiarities,  which  are  monflers  thus  produ- 
ced and  propagated.  And  to  thefe  muft  be  added,  the  changes 
produced  by  the  imagination  of  the  male  parent,  as  will  be  treat- 
ed of  more  at  large  in  No.  VL  of  this  Section. 

When  we  confider  all  thefe  changes  of  animal  form,  and  in- 
numerable others,  which  may  be  collected  from  the  books  of  nat- 
ural hiftory  ;  we  cannot  but  be  convinced,  that  the  fetus  or  em- 
bryon  is  formed  by  apportion  of  new  paits,  and  not  by  the  dif- 
tention  of  a  primordial  neft  of  germes,  included  one  within  an- 
other, like  the  cups  of  a  conjurer. 

Fourthly,  when  we  revolve  in  our  minds  the  great  fimilarity 
of  ftrufture  which  obtains  in  all  the  warm  blooded  animals,  as 
well  quadrupeds,  birds,  and  amphibious  animals,  as  in  mankind  ; 
from  the  moufe  and  bat  to  the  elephant  and  whale  ;  one  is  led 
to  conclude,  that  they  have  alike  been  produced  from  a  fimilar 
living  filament.  In  fome  this  filament  in  its  advance  to  maturi- 

o 

ty  has  acquired  hands  and  fingers,  with  a  fine  fenfe  of  touch,  -ns 
in  mankind.  In  others  it  has  acquired  claws  or  talons,  as  in 
tygers  and  eagles.  In  others,  toes  with  an  intervening  web,  or 
membrane,  as  in  feals  and  geefe.  In  others  it  has  acquired  clo- 
ven hoofs,  as  in  cows  and  fwine  ;  and  whole  hoofs  in  others,  as 
in  the  horfe.  While  in  the  bird  kind  this  original  living  fila- 
ment has  put  forth  wings  inftead  of  arms  or  legs,  and  feathers 
inftead  of  hair.  In  fome  it  has  protruded  horns  on  the  fore- 
head inftead  of  teeth  in  the  fore  part  of  the  upper  jaw  ;  in 
others  tudies  inftead  of  horns ;  and  in  others  beaks  intend  of 
either.  And  all  this  exa6lly  as  is  daily  feen  in  the  trail  fr.- 
tions  of  the  tadpole,  which  acquires  legs  and  lungs,  W!KJ 
wants  them  ;  and  lofes  his  tail,  when  it  is  no  longer  of  fervice 
to  him. 

Fifthly,  from  their  fir  ft  rudiment,  or  pvimordium,  to  the  ter- 
mination of  their  lives,  all  animals  undergo  perpetual  transform- 
ations ;  which  are  in  part  produced  by  their  own  cxerrio 
confequence  of  their  defires  and  averfions,  of  their  pleafures.  and 
their  pains,  or  of  irritations,  or  of  ailbciations  ;  and  many  of 
thefe  acquired  forms  or  propenfities  are  tranfmitted  to  their 
pofterity.  See  Sea.  XXXI.  i. 

As  air  and  water  are  (applied  to  animals  in  fufficient  profu- 
fion,  the  three  great  objects  of  defire,  which  have  changed  the 
forms  of  many  animals  by  their  exertions  to  gratify  them,  are 
thofe  of  luft,  hunger,  and  fecurity.  A  great  want  of  one  part 
of  the  animal  world  has  confided  in  the  defire  of  the  exclufive 
pofleflion  of  the  females  ;  and  thefe  have  acquired  weapons  to 
combat  each  other  for  this  purpofe,  as  the  very  thick,  fliield-Iike, 
horny  fkin  on  the  ihoulder  of  the  boar  is  a  defence  only  againt'k 

animals 


GENERATION,         SECT.  XXXIX,  4. 8, 

animals  of  his  own  fpecies,  who  ftrike  obliquely  upwards,  not 
are  his  tufhes  for  other  purpofes,  except  to  defend  himfelf,  as  he 
is  not  naturally  a  carnivorous  animal.  So  the  horns  of  the  flag 
are  (harp  to  offend  his  adverfary,  but  are  branched  for  the  pur- 
pofe  of  parrying  or  receiving  the  thrufts  of  horns  fimilar  to  his 
own,  and  have  therefore  been  formed  for  the  purpofe  of  com- 
bating other  (lags  for  the  exclufive  poffeflion  of  the  females  ; 
who  are  obferved,  like  the  ladies  in  the  times  of  chivalry,  to  at- 
tend the  car  of  the  victor. 

The  birds,  which  do  not  carry  food  to  their  young,  and  do 
not  therefore  marry,  are  armed  with  fpurs  for  the  purpofe  of 
fighting  for  the  exclufive  pofleflion  of  the  females,  as  cocks  and 
quails.  It  is  certain  that  thefe  weapons  are  not  provided  for 
their  defence  againft  other  adverfaries,  becaufe  the  females  of 
thefe  fpecies  are  without  this  armour.  The  final  caufe  of  this 
conteft  amongft  the  males  feems  to  be,  that  the  ftrongeft  and 
moft  adive  animal  fhould  propagate  the  fpecies,  which  fhould 
thence  become  improved. 

Another  great  want  confifts  in  the  means  of  procuring  food, 
which  has  diver fified  the  forms  of  all  fpecies  of  animals.  Thus 
the  nofe  of  the  fwine  has  become  hard  for  the  purpofe  of  turn- 
ing up  the  foil  in  fearch  of  infecls  and  of  roots.  The  trunk  of 
the  elephant  is  an  elongation  of  the  nofe  for  the  purpofe  of  pull- 
ing down  the  branches  of  trees  for  his  food,  and  for  taking  up 
water  without  bending  his  knees.  Beafts  of  prey  have  acquired 
ftrong  jaws  or  talons.  Cattle  have  acquired  a  rough  tongue 
and  a  rough  palate  to  pull  off  the  blades  of  grafs,  as  cows  and 
fheep.  Some  birds  have  acquired  harder  beaks  to  crack  nuts,  as 
the  parrot.  Others  have  acquired  beaks  adapted  to  break  the 
harder  feeds,  as  fparrows.  Others  for  the  fofter  feeds  of  flowers, 
or  the  buds  of  trees,  as  the  finches.  Other  birds  have  acquired 
long  beaks  to  penetrate  the  moifter  foils  in  fearch  of  infeds  or 
roots,  as  woodcocks  ;  and  others  broad  ones  to  filtrate  the  water 
of  lakes,  and  to  retain  aquatic  infects,  as  ducks.  All  which 
feem  to  have  been  gradually  produced  during  many  generations 
by  the  perpetual  endeavour  of  the  creatures  to  fupply  the  want 
of  food,  and  to  have  been  delivered  to  their  pofterity  with  conflant 
improvement  of  them  for  the  purpofes  required. 

The  third  great  want  amongft  animals  is  that  of  fecurity, 
which  feems  much  to  have  diverfified  the  forms  of  their  bodies 
and  the  colour  of  them  ;  thefe  confifl  in  the  means  of  efcaping 
other  animals  more  powerful  than  themfelves.  Hence  fome 
animals  have  acquired  wings  inftead  of  legs,  as  the  fmaller  birds, 
for  the  purpofe  of  efcape.  Others  great  length  of  fin,  or  of  mem- 
brane, as  the  flying  filh,  and  the  bat.  Others  great  fwiftnefs 

of 


SECT.  XXXIX.  4. 8.        GENERATION.  397 

of  foot,  as   the   hare.     Others   have   acquired  hard  or  armed 
fhells,  as  the  tortoife  and  the  echinus  marinus. 

Mr.  Ofbeck,  a  pupil  of  Linnaeus,  mentions  the  American 
frog-fifh,  lophius  hiftrio,  which  inhabits  the  large  floating  iflands 
of  fea-weed  about  the  Cape  of  Good  Hope,  and  has  fulcra  re- 
fembling  leaves,  that  the  fifties  of  prey  may  miftake  it  for  the 
fea-weed,  which  it  inhabits.  Voyage  to  China,  p.  113. 

The  contrivances  for  the  purpofes  of  fecurity  extend  even  to 
vegetables,  as  is  feen  in  the  wonderful  and  various  means  of 
their  concealing  or  defending  their  honey  from  infecls,  and  their 
feeds  from  birds.  On  the  other  hand  fwiftnefs  of  wing  has 
been  acquired  by  hawks  and  fwallows  to  puriue  their  prey  ;  and 
a  probofcis  of  admirable  ftru&ure  has  been  acquired  by  the  bee, 
the  moth,  and  the  humming  bird,  for  the  purpofe  of  plundering 
the  nectaries  of  flowers.  All  which  feem  to  have  been  formed 
by  the  original  living  filament,  excited  into  action  by  the  necef- 
fities  of  the  creatures,  which  poffefs  them,  and  on  which  their 
exiftence  depends. 

From  thus  meditating  on  the  great  fimilarity  of  the  (Irudlure 
of  the  warm-blooded  animals,  and  at  the  fame  time  of  the  great 
changes  they  undergo  both  before  and  after  their  nativity  ;  and 
by  confidering  in  how  minute  a  proportion  of  time  many  of  the 
changes  of  animals  above  defcribed  have  been  produced  ;  would 
it  be  too  bold  to  imagine,  that  in  the  great  length  of  time,  ilnce 
the  earth  began  to  exift,  perhaps  millions  of  ages  before  the 
commencement  of  the  hiftory  of  mankind,  would  it  be  too  bold 
to  imagine,  that  all  warm-blooded  animals  have  arifen  from  one 
living  filament,  which  THE  GREAT  FIRST  CAUSE  endued  with  an- 
imality,  with  the  power  of  acquiring  new  parts  attended  with  new 
propenfities,  directed  by  irritations,  fenfations,  volitions,  and  aflb- 
ciations  ;  and  thus  poflefling  the  faculty  of  continuing  to  improve 
by  its  own  inherent  a£Uvity,  and  of  delivering  down  thole  im- 
provements by  generation  to  its  pofterity,  world  without  end  ? 

Sixthly,  The  cold-blooded  animals,  as  the  fifli-tribes,  which 
are  furnilhed  with  but  one  ventricle  of  the  heart,  and  with  gills 
inftead  of  lungs,  and  with  fins  inilead  of  feet  or  wings,  bear  a 
great  fimilarity  to  each  other ;  but  they  differ,  neverthelefs,  fo 
much  in  their  general  ftruclure  from  the  warm-blooded  animals, 
that  it  may  not  feem  probable  at  firft  view,  that  the  fame  living 
filament  could  have  given  origin  to  this  kingdom  of  animals,  as 
to  the  former.  Yet  are  there  fome  creatures,  which  unite  or 
partake  of  both  thefe  orders  of  animation,  as  the  whales  and 
feals  ;  and  more  particularly  the  frog,  who  changes  from  an 
aquatic  animal  fumilhed  with  gills  to  an  an  aerial  one  furniihed 
with  lungs. 

The 


393  GENERATION.        SECT.  XXXIX.  4.  8. 

The  numerous  tribes  of  infers  without  wings,  from  the  fpi- 
cler  to  the  fcorpion,  from  the  flea  to  the  lobfter ;  or  with  wings, 
from  the  gnat  and  the  ant  to  the  wafp  and  the  dragon-fly,  dif- 
fer fo  totally  from  each  other,  and  from  the  red-blooded  claffes 
above  defcribed,  both  in  the  forms  of  their  bodies,  and  their 
modes  of  life  ;  befides  the  organ  of  fenfe,  which  they  feem  to 
poffefs  in  their  antennae  or  horns,  to  which  it  has  been  thought 
by  fome  naturalifts,  that  other  creatures  have  nothing  fimilar  ; 
that  it  can  fcarcely  be  fuppofed  that  this  nation  of  animals  could 
have  been  produced  by  the  fame  kind  of  living  filament,  as  the 
red-blooded  clafles  above  mentioned.  And  yet  the  changes 
which  many  of  them  undergo  in  their  early  ftate  to  that  of  their 
maturity,  are  as  different,  as  one  animal  can  be  from  another. 
As  thofe  of  the  gnat,  which  paffes  his  early  (tate  in  water,  and 
then  ftretching  out  his  new  wings,  and  expanding  his  new 
lungs,  rifes  in  the  air  ;  as  of  the  caterpillar,  and  bee-nymph, 
which  feed  on  vegetable  leaves  or  farina,  and  at  length  burfting 
from  their  felf-formed  graves,  become  beautiful  winged  inhab- 
itants of  the  fkies,  journeying  from  flower  to  flower,  and  nourifh- 
ed  by  the  ambrofial  food  of  honey. 

There  is  ftill  another  clafs  of  animals,  which  are  termed  ver^ 
mes  by  Linnseus,  which  are  without  feet,  or  brain,  and  are  her- 
maphrodites, as  worms,  leeches,  fnails,  fhell-fifh,  coralline  infects 
and  fponges  j  which  poffefs  the  fimpleft  ilruclure  of  all  animals, 
and  appear  totally  different  from  thofe  already  defcribed.  The 
fimplicity  of  their  ftrudlure,  however,  can  afford  no  argument 
againft  their  having  been  produced  from  a  living  filament  as 
above  contended. 

Laft  of  all  the  various  tribes  of  vegetables  are  to  be  enumera- 
ted amongft  the  inferior  orders  of  animals.  Of  thefe  the  an- 
thers and  ftigrnas  have  already  been  (hewn  to  poflcfs  fome  organs 
of  fenfe,  to  be  nourifhed  by  honey,  and  to  have  the  power  of 
generation  like  infects,  and  have  thence  been  announced  amongft 
the  animal  kingdom  in  Seci,  XIII.  and  to  thefe  muft  be  added 
the  buds  and  bulbs  which  conititute  the  viviparous  offspring  of 
vegetation.  The  former  I  fuppofe  to  be  beholden  to  a  fingle 
living  filament  for  their  feminal  or  amatorial  procreation  ;  and 
the  latter  to  the  fame  caufe  for  their  lateral  or  branching  gener- 
ation, which  they  poffefs  in  common  with  the  polypus,  tgenia, 
and  volvox  ;  and  the  fimplicity  of  which  is  an  argument  in  fa- 
vour of  the  fimilarity  of  its  caufe. 

Linnxus  fuppofes,  in  the  Introduction  to  his  Natural  Orders, 
that  very  few  vegetables  were  at  firft  created,  and  that  their 
numbers  were  iricreafed  by  their  intermarriages,  and  adds,  fua- 
dent  h#c  Creatoris  leges  a  fimplicibus  ad  compofita.  Many 

other 


SECT.  XXXIX.  4.8.        GENERATION. 

other  changes  feem  to  have  arifen  in  them  by  their  perpetual 
conteft  for  light  and  air  above  ground,  and  for  food  or  moifture 
beneath  the  foil.  As  noted  in  Botanic  Garden,  Part  II.  Note 
on  Cufcuta.  Other  changes  of  vegetables  from  climate,  or 
other  caufes,  are  remarked  in  the  Note  on  Curcuma  in  the  fame 
work.  From  thefe  one  might  be  led  to  imagine,  that  each  plant 
at  firit  confiiled  of  a  fingle  bulb  or  flower  to  each  root,  as  the 
gentianella  and  daify  ;  and  that  in  the  conteft  for  air  and  light 
new  buds  grew  on  the  old  decaying  flower  ftem,  (hooting  down 
their  elongated  roots  to  the  ground,  and  that  in  procefs  of  ages 
tali  trees  were  thus  formed,  and  an  individual  bulb  became  a 
fwarm  of  vegetables.  Other  plants,  which  in  this  conteft  for, 
light  and  air  were  too  flender  to  rife  by  their  own  ftrength, 
learned  by  degrees  to  adhere  to  their  neighbours,  either  by  put- 
ting forth  roots  like  the  ivy,  or  by  tendrils  like  the  vine,  or  by 
fpirai  contortions  like  the  honey-fuckle  ;  or  by  growing  upon 
them  like  the  mifleto,  and  taking  nourishment  from  their  barks  ; 
or  by  only  lodging  or  adhering  on  them,  and  deriving  nourifh- 
ment  from  the  air,  as  tillandfia. 

Shall  we  then  fay  that  the  vegetable  living  filament  was  orig- 
inally different  from  that  of  each  tribe  of  animals  above  defcri- 
btd  ?  And  that  the  productive  living  filament  of  each  of  thofe 
tribes  was  different  originally  from  the  other  ?  Or,  as  the  earth 
and  ocean  were  probably  peopled  with  vegetable  productions 
long  before  the  exiftence  of  animals  ;  and  many  families  of  thefe 
animals  long  before  other  families  of  them,  (hall  we  conjecture 
that  one  and  the  fame  kind  of  living  filaments  is  and  has  been 
the  caufe  of  all  organic  life  ? 

If  this  gradual  production  of  the  fpecies  and  genera  of  animals 
be  affented  to,  a  contrary  circumftance  may  be  fuppofed  to 
have  occurred,  namely,  that  fome  kinds  by  the  great  changes  of 
the  elements  may  have  been  deftroyed  This  idea  is  (hewn  to 
our  fenfes  by  contemplating  the  petrifactions  of  fhells,  and  of 
vegetables,  which  may  be  faid,  like  bufts  and  medals,  to  record 
the  hiitory  oi  remote  times.  Of  the  myriads  of  belemnites,  cor- 
nua  ammonis,  and  numerous  other  petrified  (hells,  which  arc 
found  in  the  maffes  of  lime-ftone,  which  have  been  produced 
by  them,  pone  now  are  ever  found  in  oirr  feas,  or  in  the  feas  of 
other  parts  of  the  world,  according  to  the  obfervations  of  many 
naturalifts.  Some  of  whom  have  imagined,  that  moft  of  the 
inhabitants  of  the  fea  and  earth  of  very  remote  times  are  now 
extinct  ;  as  they  icarcely  admit,  that  a  fingle  foffil  iliell  bears  a 
fin  t  fimilitude  to  any  recent  ones,  and  that  the  vegetable  im- 
prciiions  or  petrifactions  found  in  iron  ores,  clay,  or  fandilone, 
0£  which  there  are  many  of  the  fern  kind,  are  not  fitnilar  to  any 

plants 


4oo  GENERATION.         SECT.  XXXIX.  4.  8, 

plants  of  this  country,  nor  accurately  correfporid  with  thofe  of 
other  climates,  which  is  an  argument  countenancing  the  chang- 
es in  the  forms,  both  of  animals  and  vegetables,  during  the  pro- 
greffive  ftru&ure  of  the  globe,  which  we  inhabit.  See  Town- 
fon's  Philof.  of  Mineralogy,  p.  1 10. 

This  idea  of  the  gradual  formation  and  improvement  of  the 
animal  world  accords  with  the  obfervations  of  fome  modern  phi- 
lofophers,  who  have  fuppofed  that  the  continent  of  America  has 
been  raifed  out  of  the  ocean  at  a  later  period  of  time  than  the 
other  three  quarters  of  the  globe,  which  they  deduce  from  the 
greater  comparative  heights  of  its  mountains,  and  the  confe- 
quent  greater  coldnefs  of  its  refpedive  climates,  and  from  the 
Jefs  fize  and  ftrength  of  its  animals,  as  the  tygers  and  alligators 
compared  with  thofe  of  Afia  or  Africa.  And  laitly,  from  the 
lefs  progrefs  in  the  improvements  of  the  mind  of  its  inhabitants 
in  refpedl  to  voluntary  exertions. 

This  idea  of  the  gradual  formation  and  improvement  of  the 
animal  world  feems  not  to  have  been  unknown  to  the  ancient 
philofophers.  Plato  having  probably  obferved  the  reciprocal 
generation  of  inferior  animals,  as  fnails  and  worms,  was  of  opin- 
ion, that  mankind  with  all  other  animals  were  originally  herma- 
phrodites during  the  infancy  of  the  world,  and  were  in  procefs 
of  time  feparated  into  male  and  female.  The  breaiis  and 
teats  of  all  male  quadrupeds,  to  which  no  ufe  can  be  now  af- 
figned,  adds  perhaps  fome  fhadow  of  probability  to  this  opinion, 
Linnxus  excepts  the  horfe  from  the  male  quadrupeds,  who  have 
tSats  ;  which  might  have  (hewn  the  earlier  origin  of  his  exift- 
.  ence  -,  but  Mr.  J.  Hunter  afierts,  that  he  has  difcovered  the  vef- 
tiges  of  them  on  his  (heath,  and  has  at  the  fame  time  enriched 
natural  hiftory  with  a  very  curious  fad  concerning  the  male 
pigeon  ;  at  the  time  of  hatching  the  eggs  both  the  male  and  fe- 
male pigeon  undergo  a  great  change  in  their  crops ;  which  thick- 
en and  become  corrugated,  and  fecrete  a  kind  of  milky  fluid, 
which  coagulates,  and  with  which  alone  they  for  a  few  days 
feed  their  young,  and  afterwards  feed  them  with  this  coagulated 
fluid  mixed  with  other  food.  How  this  refembles  the  breafts 
of  female  quadrupeds  after  the  prod uft ion  of  their  young  I  and 
how  extraordinary,  tha*t  the  male  fhould  at  this  time  give  milk 
as  well  as  the  female  !  See  Botanic  Garden,  Part  II.  Note  on 
Curcuma. 

The  late  Mr.  David  Hume,  in  his  pofthumous  works,  places 
the  powers  of  generation  much  above  thofe  of  our  boafted  rea- 
fon ;  and  adds,  that  reafon  can  only  make  a  machine,  as  a  clock 
or  a  (hip,  but  the  power  of  generation  makes  the  maker  of  the 
machine  ;  and  probably  from  having  obierved,  that  the  greateft 

part 


SECT.  XXXIX.  5.  i.         GENERATION.  401 

part  of  the  earth  has  been  formed  out  of  organic  reqrements  ; 
as  the  immenfe  beds  of  limeftone,  chalk,  marble,  from  the  (hells 
of  fifh  ;  and  the  extend ve  provinces  of  clay,  fandftone,  ironftone, 
coals,  from  decompofed  vegetables  ;  all  which  have  been  firft 
produced  by  generation,  or  by  the  fecretions  of  organic  life  ;  he 
concludes  that  the  world  itfelf  might  have  been  generated,  rath- 
er than  created ;  that  is,  it  might  have  been  gradually  produced 
from  very  fmall  beginnings,  increafing  by-  the  activity  of  its  in- 
herent principles,  rather  than  by  a  fudtien  evolution  of  the 
whole  by  the  Almighty  fiat. — What  a  magnificent  idea  of  the 
infinite  power  of  THE  GREAT  ARCHITECT  !  THE  CAUSE  OF 
CAUSES  !  PARENT  OF  PARENTS  !  LNS  ENTIUM  ! 

For  if  we  may  compare  infinities,  it  would  feem  to  require  a 
greater  infinity  of  power  to  caufe  the  caufes  of  effefts,  than  to 
caufe  the  effects  themfelves.  This  idea  is  analogous  to  the  im- 
proving excellence  obfervable  in  every  part  of  the  creation  ; 
fuch  as  in  the  progreflive  increafe  of  the  folid  or  habitable  parts 
of  the  earth  from  water  ;  and  in  the  progreflive  increafe  of  the 
wifdom  and  happinefs  of  its  inhabitants ;  and  is  confonant  to 
the  idea  of  our  prefent  fituation  being  a  ftate  of  probation,  which 
by  our  exertions  we  may  improve,  and  are  confequently  refpon- 
fible  for  our  actions. 

V.  i.  The  efficient  caufe  of  the  various  colours  of  the  eggs 
of  birds,  and  of  the  hair  and  feathers  of  animals,  is  a  fubject  fo 
curious,  that  I  [hall  beg  to  introduce  it  in  this  place.  The  col- 
ours of  many  animals  feem  adapted  to  their  purpofes  of  con- 
cealing themfelves  either  to  avoid  danger,  or  to  fpring  upon  their 
prey.  Thus  the  fnake  and  wild  cat,  and  leopard,  are  fo  colour- 
ed as  to  refemble  dark  leaves  and  their  lighter  interfaces  j  birds 
refemble  the  colour  of  the  brown  ground,  or  the  green  hedges, 
which  they  frequent ;  and  moths  and  butterflies  are  coloured 
like  the  flowers  which  thev  rob  of  their  honey.  Many  inftances 
are  mentioned  of  this  kind  in  Botanic  Garden,  Part  II.  Note 
on  Rubia. 

Thefe  colours  have,  however,  in  fome  inftances  another  ufe, 
as  the  black  diverging  area  from  the  eyes  of  the  fwan  ;  which, 
as  his  eyes  are  placed  lefs  prominent  than  thofe  of  other  birds, 
for  the  convenience  of  putting  down  his  head  under  water,  pre- 
vents the  rays  of  light  fro-M  being  reflected  into  his  eyes,  and 
thus  dazzling  his  fight,  both  in  air  and  beneath  the  water ;  which 
mull  have  happened,  if  that  furface  had  been  white  Jike  the  reft 
of  his  feathers. 

There  is  a  (till  more  wonderful  thing  concerning  thefe  colours 
adapted  to  the  purpofe  of  concealment ;  which  is,  thar  the  eggs 
of  birds  are  fo  coloured  as  to  refemble  the  colour  of  the  adjacent. 

VOL.  I.  D  D  d  objects 


402  GENERATION.        SECT.  XXXIX.  5.  i. 

objects  and  their  interftices.  The  eggs  of  hedgebirds  are  green* 
ilh  with  dark  fpots  ;  thofe  of  crows  and  magpies,  which  are  feen 
from  beneath  through  wicker  nefts,  are  white  with  dark  fpots  ; 
and  thofe  of  larks  and  partridges  are  rufTet  or  brown,  like  their 
nefts  or  fituations. 

A  thing  (lill  more  aftonifhing  is,  that  many  animals  in  coun- 
tries covered  with  fnow  become  white  in  winter,  and  are  faid  to 
change  their  colour  again  in  the  warmer  months,  as  bears,  hares, 
and  partridges.  Our  domefticated  animals  lofe  their  natural 
colours,  and  break  into  great  variety,  as  horfes,  dogs,  pigeons. 
The  final  caufe  of  thefe  colours  is  eafily  underftood,  as  they 
ferve  fome  purpofes  of  the  animal,  but  the  efficient  caufe  would 
feem  almoft  beyond  conjecture. 

Firft,  the  choroid  coat  of  the  eye,  on  which  the  femitranfpa- 
rent  retina  is  expanded,  is  of  different  colour  in  different  ani- 
mals •,  in  thofe  which  feed  on  grafs  it  is  green  ;  from  hence 
there  would  appear  fome  connexion  between  the  colour  of  the 
choroid  coat  and  of  that  conftantly  painted  on  the  retina  by  the 
green  grafs.  Now,  when  the  ground  becomes  covered  with 
fnow,  it  would  feem,  that  that  action  of  the  retina,  which  is 
called  whitenefs,  being  conftantly  excited  in  the  eye,  may  be 
gradually  imitated  by  the  extremities  of  the  nerves  of  touch,  or 
rete  mucofum  of  the  ficin.  And  if  it  be  fuppofed,  that  the  ac- 
tion of  the  retina  in  producing  the  perception  of  any  colour 
confifts  in  fo  difpofmg  its  own  fibres  or  furface,  as  to  reflect 
thofe  coloured  rays  only,  and  tranfmit  the  others  like  foap-bub- 
bles  i  then  that  part  of  the  retina,  which  gives  us  the  perception 
of  fnow,  muft  at  that  time  be  white  ;  and  that  which  gives  us 
the  perception  of  grafs,  muft  be  green. 

Then  if  by  the  laws  of  imitation,  as  explained  in  Section  XII. 
33.  and  XXXIX-  6  the  extremities  of  the  nerves  of  touch  in 
the  rete  mucofum  be  induced  into  fimilar  action,  the  (kin  or 
feathers,  or  hair,  may  in  like  manner  fo  difpofe  their  extreme 
fibres,  as  to  reflect  white  ;  for  it  is  evident,  that  all  thefe  parts 
were  originally  obedient  to  irritative  motions  during  their 
growth,  and  probably  continue  to  be  fo  ;  that  thofe  irritative 
motions  are  not  liable  in  a  healthy  ftate  to  be  fucceeded  by  fen- 
fation  ;  which  however  is  no  uncommon  thing  in  their  difeafed 
ftate,  or  in  their  infant  ftate,  as  in  plica  polonica,  and  in  very 
young  pen-feathers,  which  are  ftill  full  of  blood. 

It  was  fhewn  in  Section  XV  on  the  Production  of  Ideas,  that 
the  moving  organ  of  fenfe  in  fome  circumftances  refembled  the 
object  which  produced  that  motion.  Hence  it  may  be  conceiv- 
ed, that  the  rete  mucofum,  which  is  the  extremity  of  the  nerves 
of  touch,  may  by  imitating  the  motions  of  the  retina  become 

coloured.. 


SECT.  XXXIX.  5.  2.       GENERATION-  403 

coloured.  And  thus,  like  the  fable  of  the  chameleon,  all  ani- 
mals may  pofTefs  a  tendency  to  be  coloured  fomewhat  like  the 
colours  they  mod  frequently  infpeft,  and  finally,  that  colours 
may  be  thus  given  to  the  egg- (hell  by  the  imagination  of  the  fe- 
male parent  ;  which  (hell  is  previoufly  a  mucous  membrane,  in- 
dued with  irritability,  without  which  it  could  not  circulate  its 
fluids,  and  increafe  in  its  bulk.  Nor  is  this  more  wonderful  than 
that  a  (ingle  idea  of  imagination  mould  in  an  indant  colour  the 
whole  furface  of  the  body  a  bright  fcarlet,  as  in  the  blufh  of 
(hame,  though  by  a  very  different  procefs.  In  this  intricate  fub- 
jeft  nothing  but  loofe  analogical  conjectures  can  be  had,  which 
may  however  lead  to  future  difcoveries  ;  but  certain  it  is  that 
both  the  change  of  the  colour  of  animals  to  white  in  the  winters 
of  fnowy  countries,  and  the  fpots  on  birds'  eggs,  mud  have  fome 
efficient  caufe ;  fince  the  uniformity  of  their  production  (hews 
it  cannot  arife  from  a  fortuitous  concurrence  of  circumftances  ; 
and  how  is  this  efficient  caufe  to  be  detected,  or  explained,  but 
from  its  analogy  to  other  animal  fads  ? 

2.  The  nutriment  fupplied  by  the  female  parent  in  vivipa- 
rous animals  to  their  young  progeny  may  be  divided  into  three 
kinds,  correfponding  with  the  age  of  the  new  creature,  i.  The 
nutriment  contained  in  the  ovum  as  previoufly  prepared  for  the 
embryon  in  the  ovary.  2.  The  liquor  amnii  prepared  for  the 
fetus  in  the  uterus,  and  in  which  it  fwims  ;  and  laftly,  the  milk 
prepared  in  the  pectoral  glands  for  the  new-born  child.  There 
is  reafon  to  conclude  that  variety  of  changes  may  be  produced 
in  the  new  animal  from  all  thefe  fources  of  nutriment,  but  par- 
ticularly from  the  firft  of  them. 

The  organs  of  digeftion  and  fanguification  in  adults,  and 
afterwards  thofe  of  fecretion,  prepare  or  feparate  the  particles 
proper  for  nourifhment  from  other  combinations  of  matter,  or 
recombine  them  into  new  kinds  of  matter,  proper  to  excite  into 
action  the  filaments,  which  abforb  or  attract  them  by  animal  ap- 
petency. In  this  procefs  we  mud  attend  not  only  to  the  action 
of  the  living  filament  which  receives  a  nutritive  particle  to  its 
bofom,  but  alfo  to  the  kind  of  particle,  in  reipect  to  form,  or 
fize,  or  colour,  or  hardnefs,  which  is  thus  preyioufly  prepared  for 
it  by  digeftion,  fanguification,  and  fecretion.  Now  as  the  firil 
filament  of  entity  cannot  be  furnimed  with  the  preparative  or- 
gans above  mentioned,  the  nutritive  particles,  which  are  at  firft 
to  be  received  by  it,  are  prepared  by  the  mother  ;  and  depofited 
in  the  ovum  ready  for  its  reception.  Thefe  nutritive  particles 
mud  be  fuppofed  to  differ  in  fome  refpects,  when  thus  prepared 
by  different  animals,  They  may  differ  in  fize,  folidity,  colour, 
and  form  j  and  yet  may  be  fufficiently  congenial  to  the  living 

filament, 


494  GENERATION.        SECT.  XXXTX.  g.  *. 

filamenr,  to  which  they  are  applied,  as  to  excite  its  activity  by 
their  ftimulus,  and  its  animal  appetency  to  receive  them,  and  to 
combine  them  with  itfelf  into  organization. 

By  the  firft  nutriment  thus  prepared  for  the  embryon  is  not 
meant  the  liquor  am  nil,  which  is  produced  afterwards,  nor  the 
larger  exterior  parts  of  the  white  of  the  egg  ;  but  the  fluid  pre- 
pared, I  fuppofe,  in  the  ovary  of  viviparous  animals,  and  that 
which  immediately  furrounds  the  cicatricula  of  an  impregnated 
egg,  and  is  vifible  to  the  eye  in  a  boiled  one. 

Now  thefe  ultimate  particles  of  animal  matter  prepared  by  the 
glands  of  the  mother  may  be  fuppofed  to  refemble  the  fimilar 
ultimate  particles,  which  were  prepared  for  her  own  nourifh- 
ment ;  that  is,  to  the  ultimate  particles  of  which  her  own  or- 
ganization confifts.  And  that  hence  when  thefe  become  com- 
bined with  a  new  embryon,  which  in  its  early  ftate  is  not  fur- 
nifhed  with  fiomach,  or  glands,  to  alter  them  ;  that  new  embry- 
on will  bear  fome  refemblance  to  the  mother. 

This  feerns  to  be  the  origin  of  the  compound  forms  of  mules, 
which  evidently  partake  of  both  parents,  but  principally  of  the 
male  parent.  In  this  production  of  chimeras  the  ancients  feem 
to  have  indulged  their  fancies,  whence  the  fphinxes,  griffins, 
dragons,  centaurs,  and  minotaurs,  which  are  vanished  from 
modern  credulity. 

It  would  feem,  that  in  thefe  unnatural  conjunctions,  when  the 
nutriment  depofited  by  the  female  was  fo  ill  adapted  to  ftimu- 
late  the  living  filament  derived  from  the  male  into  action,  and 
to  be  received,  or  embraced  by  it,  and  combined  with  it  into 
organization,  as  not  to  produce  the  organs  neceflary  to  life,  as 
the  brain,  or  heart,  or  (tomach,  that  no  mule  was  produced. 
Where  all  the  parts  neceflary  to  life  in  thefe  compound  animals 
were  formed  fufficiently  perfect,  except  the  parts  of  generation, 
thofe  animals  were  produced  which  are  now  called  mules. 

The  formation  of  the  organs  of  fexual  generation,  in  contra- 
diftinftion  to  that  by  lateral  buds,  in  vegetables,  and  in  ibme 
animals,  as  the  polypus,  the  taenia,  and  the  volvox,  feems  the 
chef  d'oeuvre,  the  mafter-piece  of  nature  ;  as  appears  from  ma- 
ny flying  infects,  as  in  moths  and  butterflies,  who  feem  to  un- 
dergo a  general  change  of  their  forms  folely  for  the  purpofe  of 
fexual  reproduct ion,  and  in  all  other  animals  this  organ  is  not 
complete  till  the  maturity  of  the  creature.  Whence  it  happens 
that,  in  the  copulation  of  animals  of  different  fpecies,  the  parts 
neceflary  to  life  are  frequently  completely  formed  $  but  thofe 
for  the  purpofe  of  generation  are  defective,  as  requiring  a  nicer 
organization  ;  or  more  exact  coincidence  of  the  particles  of  nu- 
triment to  the  irritabilities  or  appetencies  of  the  original  living 

filement. 


SECT.  XXXIX.  5. 2.      GENERATION.  405 

filament.  Whereas  thofe  mules,  where  all  the  parts  could  be 
perfectly  formed,  may  have  been  produced  in  early  periods  of 
time,  and  may  have  added  to  the  numbers  of  our  various  fpecies 
of  animals,  as  before  obferved. 

As  this  production  of  mules  is  a  conftant  effect  from  the  con- 
junction of  different  fpecies  of  animals,  thofe  between  the  horfe 
and  the  female  afs  always  refembling  the  horfe  more  than  the 
afs  ;  and  thofe  on  the  contrary,  between  the  male  afs  and  the 
mare,  always  refembling  the  afs  more  than  the  mare  ;  it  cannot 
be  afcribed  to  the  imagination  of  the  male  animal  which  cannot 
be  fuppofed  to  operate  fo  uniformly  ;  but  to  the  form  of  the 
firft  nutritive  particles,  and  to  their  peculiar  ftimulus  exciting 
the  living  filament  to  feleft  and  combine  them  with  itfelf. 
There  is  a  fimilar  uniformity  of  effect  inrefpe6l  to  the  colour 
of  the  progeny  produced  between  a  white  man,  and  a  black 
woman,  which,  if  lam  well  informed,  is  always  of  the  mulatto 
kind,  or  a  mixture  of  the  two  ;  which  may  perhaps  be  imputed 
to  the  peculiar  form  of  the  particles  of  nutriment  fupplied  to 
the  embryon  by  the  mother  at  the  early  period  of  its  exiftence, 
and  their  peculiar  ftimulus  ;  as  this  effecl,  like  that  of  the  mule 
progeny  above  treated  of,  is  uniform  and  confident,  and  cannot 
therefore  be  afcribed  to  the  imagination  of  either  of  the  parents. 

Dr.  Thunberg  obferves,  in  his  Journey  to  the  Cape  of  Good 
Hope,  that  there  are  fome  families,  which  have  defcended  from 
blacks  in  the  female  line  for  three  generation.  The  firft  genera- 
tion proceeding  from  an  European,  who  married  a  tawny  Have, 
remains  tawny,  but  approaches  to  a  white  complexion  ;  but  the 
children  of  the  third  generation,  mixed  with  Europearis>  become 
quite  white,  and  are  often  remarkably  beautiful.  Vol.  i.  p.  112. 

When  the  embryon  has  produced  a  placenta,  and  furnifhed 
itfeif  with  veflels  for  fele&ion  of  nutritious  particles,  and  for 
oxygenation  of  them,  no  great  change  in  its  form  or  colour  is 
likely  to  be  produced  by  the  particles  of  fuftenance  it  now  takes 
from  the  fluid,  in  which  it  is  immerfed  ;  becaufe  it  has  now  ac- 
quired organs  to  alter  or  new  combine  them.  Hence  it  con- 
tinues to  grow  whether  this  fluid,  in  which  it  fwims,  be  formed 
by  the  uterus  or  by  any  other  cavity  of  the  body,  as  in  extra- 
uterine  geitation  ;  and  which  would  feem  to  be  produced  by 
the  ftimulus  of  the  fetus  on  the  fides  of  the  cavity,  where  it  is 
found,  as  mentioned  before.  And  thirdly,  there  is  ftill  lefs  rea- 
fon  to  expect  any  unnatural  change  to  happen  to  the  child  after 
its  birth  from  the  difference  of  the  milk  it  now  takes  ;  becaufe 
it  has  acquired  a  ftornach,  and  lungs,  and  glands,  of  fufficient 
power  to  decompofe  and  recombine  the  milk  ;  and  thus  to  pre- 
pare from  it  the  various  kinds  of  nutritious  particles,  which  the 
appetencies  of  the  various  fibrils  or  nerves  may  require. 

From 


406  GENERATION.       SECT.  XXXIX.  6.  i. 

From  all  this  reafoning  I  would  conclude,  that  though  the 
imagination  of  the  female  may  be  fuppofed  to  affedt  the  embry- 
on by  producing  a  difference  in  its  early  nutriment ;  yet  that  no 
fuch  power  can  afFe£t  it  after  it  has  obtained  a  placenta,  and 
other  organs  ;  which  may  feledt  or  change  the  food,  which  is 
prefented  to  it  either  in  the  liquor  amnii,  or  in  the  milk.     Now 
as  the  eggs  in  pullets,  like  the  feeds  in  vegetables,  are  produced 
gradually,  long  before  they  are  impregnated,  it  does  not  appear 
how  any  fudden  effect,  of  imagination  of  the  mother  at  the  time 
of  impregnation  can  produce  any  confiderable  change  in  the  nu- 
triment already  thus  laid  up  for  the  expeCted  or  defired  embryon* 
And  that  hence  any  changes  of  the  embryon,  except  thofe  uni- 
form ones  in  the  production  of  mules  and    mulattoes,  more 
probably  depend  on  the  imagination  of  the  male  parent.     At 
the  fame  time   it  feems  manifeft,  that  thofe  monftrous  binhs, 
which  confift  in  fome   deficiencies  only,  or  fome  redundancies 
of  parts,  originate  from  the  deficiency  or  redundance  of  the  firft 
nutriment  prepared  in  the  ovary,  or  in  the  part  of  the  egg  im- 
mediately furrounding  the  cicatricula,  as  defcribed  above  ;  and 
which  continues  fome  time  to  excite  the  firft  living  filament 
into  a£tion,  after  the  fimple  animal  is  completed  ;  or  ceafes  to 
excite  it,  before  the  complete  form  is  accompiifhed.     The  for- 
mer of  thefe   circumftances  is  evinced  by  the  eggs  with  double 
yolks,  which  frequently  happen  to  our  domefticated  poultry,  and 
\vhich,  I  believe,  are  fo  formed  before  impregnation,  but  which 
would   be  well  worth  attending  to ,  both  before  and  after  im- 
pregnation ;  as  it  is  probable,  fomething  valuable  on  this  iubjedl 
might  be  learnt  from  them.      The   latter  circumftance,  or  that 
of  deficiency  of  original   nutriment,  may  be  deduced  from  re- 
verfe  analogy. 

There  are,  however§  other  kinds  of  monftrous  births,  which 
neither  depend  on  deficiency  of  parts,  or  fupernumerary  ones  ; 
nor  are  owing  to  the  conjunction  of  animals  of  different  fpecies  5 
but  which  appear  to  be  new  conformations,  or  new  difpofitions 
of  parts  in  refpedt  to  each  other,  and  which,  like  the  variation 
of  colours  and  forms  of  our  domefticated  animals,  and  probably 
the  fexual  parts  of  all  animals,  may  depend  on  the  imagination 
of  the  male  parent,  which  we  now  come  to  confider. 

VI.  i.  The  nice  actions  of  the  extremities  of  our  various 
glands  are  exhibited  in  their  various  productions,  which  are  be- 
lieved to  be  made  by  the  gland,  and  not  previoufly  to  cxift  as 
fuch  in  the  blood. ,  Thus  the  glands,  which  conftitute  the  liver, 
make  bile ;  thofe  of  the  ftomach  make  gaftric  acid  j  thofe  be- 
neath the  jaw,  faliva  j  thofe  of  the  ears,  ear-wax  ;  and  the  like. 
Every  kind  pf  gland  mult  pofiefs  a  peculiar  irritability,  and 

probably 


SECT.  XXXIX.6.  i .       GENERATION.  407 

probably  a  fenfibility,  at  the  early  (late  of  its  exiftence  ;  and 
muft  be  furnifhed  with  a  nerve  of  fenfe,  or  of  motion,  to  per- 
ceive, and  to  felect,  and  to  combine  the  particles,  which  com  - 
pofe  the  fluid  it  fecretes.  And  this  nerve  of  fenfe  which  per- 
ceives the  different  articles  which  compofe  the  blood,  muft  at 
lead  be  conceived  to  be  as  fine  and  fubtile  an  organ,  as  the  op^ 
tic  or  auditory  nerve,  which  perceives  light  or  found.  See 
Sect.  XIV.  9. 

But  in  nothing  is  this  nice  action  of  the  extremities  of  the 
blood- veflels  fo  wonderful,  as  in  the  production  of  contagious 
matter.  A  fmall  drop  of  variolous  contagion  diffufed  in  the 
blood,  or  perhaps  only  by  being  inferted  beneath  the  cuticle, 
after  a  time,  (as  about  a  quarter  of  a  lunation,)  excites  the  ex- 
treme veflels  of  the  (kin  into  certain  motions,  which  produce  a 
fimilar  contagious  material,  filling  with  it  a  thoufand  puftules. 
So  that  by  irritation,  or  by  fenfation  in  confequence  of  irrita- 
tion, or  by  affbciation  of  motions,  a  material  is  formed  by  the 
extremities  of  certain  cutaneous  veflels,  exactly  fimilar  to  the 
ftimuiating  material,  which  caufed  the  irritation,  or  confequent 
feniation,  or  aflbciation. 

Many  glands  of  the  body  have  their  motions,  and  in  confe- 
quence their  fecreted  fluids,  arTecled  by  pleafurable  or  painful 
ideas,  fince  they  are  in  many  inftances  influenced  by  fenfitive  aflb- 
eiations,  as  well  as  by  the  irritations  of  the  particles  of  the  pafling 
blood.  Thus  the  idea  of  meat,  excited  in  the  minds  of  hungry 
dogs,  by  their  fenfe  of  vifion,  or  of  fmell,  increafes  the  difcharge 
of  faliva,  both  in  quantity  and  vifcidity  ;  as  is  feen  in  its  hanging 
down  in  threads  from  their  mouths,  as  they  (land  round  a  din- 
ner-table. The  fenfations  of  pleafure,  or  of  pain,  of  peculiar 
kinds,  excite  in  the  fame  manner  a  great  difcharge  of  tears  ; 
which  appear  alfo  to  be  more  faline  at  the  time  of  their  fecretion, 
from  their  inflaming  the  eyes  and  eye- lids.  The  palenefs  from 
fear,  and  the  blufh  of  fhame,  and  of  joy,  are  other  inftances  of 
the  effects  of  painful  or  pleafurable  fenfations,  on  the  extremi- 
ties of  the  arterial  fyftem. 

It  is  probable,  that  the  pleafurable  fenfation  excited  in  the 
ftomach  by  food,  as  well  as  its  irritation,  contributes  to  excite 
into  action  the  gaftric  glands,  and  to  produce  a  greater  fecre- 
tion of  their  fluids.  The  fame  probably  occurs  in  the  fecretion 
of  bile;  that  is,  that  the  pleafurable  fenfation  excited  in  the 
ftomach,  affects  this  fecretion  by  fenfitive  aflbciation,  as  well  as 
by  irritative  aflbciation. 

And  laftly  it  would  feem,   that  all   the  glands  in  the  body 
have  their  fecreted  fluids  affected,  in   quantity  and  quality,  by 
the  pleafurable  or  painful  fenfations,  which  produce  or  accom- 
pany 


4o8  GENERATION.        SECT.  XXXIX.  6.  2. 

company  thofe  fecretions.  And  that  the  pleafurable  fenfations 
arifing  from  thefe  fecretions  may  conftitute  the  unnamed  pleaf- 
ure  of  exiftence,  which  is  contrary  to  what  is  meant  by  taediuru 
vifae,  or  ennui  ;  and  by  which  we  fometimes  feel  ourfelves  hap- 
py, without  being  able  to  afcribe  it  to  any  mental  caufe,  as  af- 
ter an  agreeable  meal,  or  in  the  beginning  of  intoxication 

Now  it  would  appear  that  no  fecretion  or  excretion  of  fluid 
is  attended  with  fo  much  agreeable  fenfation,  as  that  of  the 
femen  ;  and  it  would  thence  follow,  that  the  glands  which  per- 
form this  fecretion,  are  more  likely  to  be  much  affected  by  their 
catenations  with  pleafurable  fenfations.  This  circumftance  is 
certain,  that  much  more  of  this  fluid  is  produced  in  a  given 
time,  when  the  object  of  its  exclufion  is  agreeable  to  the  mind. 
2.  A  forcible  argument,  which  {hews  the  neceflity  of  pleafura- 
ble fenfation  to  copulation,  is,  that  the  aft  cannot  be  performed 
without  it ;  it  is  eafily  interrupted  by  the  pain  of  fear  or  bafh- 
fulnefs  ;  and  no  efforts  of  volition  or  of  irritation  can  effect 
this  procefs,  except  fuch  as  induce  pleafurable  ideas  or  fenfa- 
tions. See  Sed.  XXXIII.  r.  i.  ' 

A  curious  analogical  circumftance  attending  hermaphrodite 
infects,  as  fnails  and  worms,  dill  further  illuftrates  this  theory  j 
if  the  fnail  or  worm  could  have  impregnated  itfelf,  there  might 
have  been  a  faving  of  a  large  male  apparatus  ;  but  as  this  is 
not  fo  ordered  by  nature,  but  each  fnail  and  worm  reciprocally 
receives  and  gives  impregnation,  it  appears,  that  a  pleafurable 
excitation  feems  alfo  to  have  been  required. 

This  wonderful  circumttance  of  many  infects  being  her- 
maphrodites, and  at  the  fame  time  not  having  power  to  im- 
pregnate themfelves,  is  attended  to  by  Dr.  Lifter,  in  his  Exer- 
citationes  Anatom.  de  Limacibus,  p.  145  ;  who,  amongft  many 
other  final  caufes,  which  he  adduces  to  account  for  it,  adds,  ut 
tarn  triftibus  et  frigidis  animalibus  majori  cum  voluptate  perfi- 
ciatur  venus. 

There  is>  however,  another  final  caufe,  to  which  this  circum- 
ftance may  be  imputed  :  it  was  obferved  above,  that  vegetable 
buds  and  bulbs,  which  are  produced  without  a  mother,  are  al- 
ways exact  refemblances  of  their  parent  ;  as  appears  in  grafting 
fruit  trees,  and  in  the  flower-buds  of  the  dioeceous  plants, 
which  are  always  of  the  fame  fex  on  the  fame  tree  ;  hence 
thofe  hermaphrodite  infects,  if  they  could  have  produced  young 
without  a  mother,  would  not  have  been  capable  of  that  change 
or  improvement,  which  is  feen  in  all  other  animals,  and  in  thofe 
vegetables,  which  are  procreated  bv  the  male  embryon  received 
and  rtourifhed  by  the  female.  And  it  is  hence  probable,  that 
if  vegetables  could  only  have  been  produced  by  buds  and  bulbs, 

and 


SECT.  XXXIX.  6.  3.        GENERATION.  409 

and  not  by  fexual  generation,  that  there  would  not  at  this  time 
have  exifted  one  thoufandth  part  of  their  prefent  number  of  fpe- 
cies  ;  which  have  probably  been  originally  mule -productions  ; 
nor  could  any  kind  of  improvement  or  change  have  happened 
to  them  except  by  the  difference  of  foil  or  climate. 

3.  I  conclude  that  the  imagination  of  the  male  at  the  time 
of  copulation,  or  at  the  time  of  the  fecretion  of  the  femen,  may 
fo  affect  this  fecretion  by  irritative  or  fenfitive  afTbciation,  as 
defcribed  in  No.  V.  I.  of  this  feet  ion,  as  to  caufe  the  produc- 
tion of  fimilarity  of  form  and  of  features,  with  the  diftinclion 
'  of  fex  ;  as  the  motions  of  the  chiflcl  of  the  turner  imitate  or 
correfpond  with  thofe  of  the  ideas  of  the  artift.  It  is  not  here 
fo  be  under  flood,  that  the  firft  living  fibre,  which  is  to  form  an 
animal,  is  produced  with  any  fimilarity  of  form  to  the  future  an- 
imal ;  but  with  propenfities,  or  appetencies,  which  (hall  produce 
by  accretion  of  parts  the  fimilarity  of  form,  feature,  or  fex,  cor- 
refponding  to  the  imagination  of  the  father. 

Our  ideas  are  movements  of  the  nerves  of  fenfe,  as  of  the 
optic  nerve  in  recollecting  vifible  ideas,  fuppofe  of  a  triangular 
piece  of  ivory.  The  fine  moving  fibres  of  the  retina  act  in  a 
manner  to  which  I  give  the  name  of  white ;  and  this  action  is 
confined  to  a  defined  part  of  it  ;  to  which  figure  I  give  the 
name  of  triangle.  And  it  is  a  preceding  pleafurable  fenfa- 
tion  exifting  in  my  mind,  which  occafions  me  to  produce 
this  particular  motion  of  the  retina,  when  no  triangle  is  pre«? 
fent.  Now  it  is  probable,  that  the  acting  fibres  of  the  ulti- 
mate terminations  of  the  fecreting  apertures  of  the  veiTels  of 
the  redes,  are  as  fine  as  thofe  of  the  retina  ;  and  that  they  are 
liable  to  be  thrown  into  that  peculiar  action,  which  marks  the 
fex  of  the  fecreted  embryon,  by  fympathy  with  the  pleafurable 
motions  of  the  nerves  of  vifion  or  of  touch  ;  that  is,  with  certain 
ideas  of  imagination.  From  hence  it  would  appear,  that  the 
world  has  long  been  miltaken  in  afcribing  great  power  to  the 
imagination  of  the  female,  whereas  from  this  account  of  it,  the 
real  power  of  imagination,  in  the  act  of  generation,  belongs 
folely  to  the  male.  See  Seel.  XII.  3.  3. 

It  may  be  objected  to  this  theory,  that  a  man  may  be  fuppof- 
ed  to  have  in  his  mind,  the  idea  of  the  form  and  features  of  the 
female,  rather  than  his  own,  and  therefore  there  (hould  be  a 
greater  number  of  female  births.  On  the  contrary,  the  general 
idea  of  our  own  form  occurs  to  every  one  almolt  perpetually, 
and  is  termed  confcioufnefs  of  our  exiftence,  and  thus  may  ef- 
fect, that  the  number  of  males  furpafles  that  of  females.  See 
Sect  XV.  3.  4.  and  XVIII.  13.  And  what  further  con- 
firms this  idea  is,  that  the  male  children  moft  frequently 

VOL.  I.  EEC  refemble 


4io  GENERATION.         SECT.  XXXIX.  i.  4. 

refemble  the  father  in  form,  or  feature,  as  well  as  in  fex  ;  and 
the  female  mod  frequently  refemble  the  mother,  in  feature,  and 
form,  as  well  as  in  fex. 

It  may  again  be  objected,  if  a  female  child  fometimes  refem- 
bles  the  father,  and  a  male  child  the  mother,  the  ideas  of  the 
father,  at  the  time  of  procreation,  muft  fuddenly  change  from 
himfelf  to  the  mother,  at  the  very  inftant,  when  the  embryon  is 
fecreted  or  formed.  This  difficulty  ceafes  when  we  confider, 
that  it  is  as  eafy  to  form  an  idea  of  feminine  features  with  male 
organs  of  reproduction,  or  of  male  features  with  female  ones, 
as  the  contrary ;  as  we  conceive  the  idea  of  a  fphinx  or  mer- 
maid as  eafily  and  as  didin&ly  as  of  a  woman.  Add  to  this, 
that  at  the  time  of  procreation  the  idea  of  the  male  organs,  and 
of  the  female  features,  are  often  both  excited  at  the  fame  time, 
by  contaft,  or  by  vifion. 

I  afk,  in  my  turn,  is  the  fex  of  the  embryon  produced  by  ac- 
cident ?  Certainly  whatever  is  produced  has  a  caufe  ;  but  when 
this  caufe  is  too  minute  for  our  comprehenfion,  the  effeft  is  faid 
in  common  language  to  happen  by  chance,  as  in  throwing  a 
certain  number  on  dice.  Now  what  caufe  can  occafionally  pro- 
duce the  male  or  female  character  of  the  embryon,  but  the  pe- 
culiar actions  of  thofe  glands,  which  form  the  embryon  ?  And 
•what  can  influence  or  govern  thefe  aftions  of  the  gland,  but  its 
afTociations  or  catenations  with  other  fenfitive  motions  ?  Nor  is 
this  more  extraordinary,  than  that  the  catenations  of  irritative 
motions  with  the  apparent  vibrations  of  objefts  at  fea  fhould 
produce  ficknefs  of  the  ftomach  ;  or  that  a  naufeous  ftory  fhould 
occafion  vomiting. 

4.  An  argument  which  evinces  the  effeft  of  imagination  on 
the  firft  rudiment  of  the  embryon,  may  be  deduced  from  the 
produ£lion  of  fome  peculiar  monfters.  Such,  for  inftance,  as 
thofe  which  have  two  heads  joined  to  one  body,  and  thofe  which 
have  two  bodies  joined  to  one  head  ;  of  which  frequent  exam- 
ples occur  amongft  our  domefticated  quadrupeds,  and  poultry. 
It  is  abfurd  to  fuppofe,  that  fuch  forms  could  exift  in  primordial 
germes,  as  explained  in  No.  IV.  4.  of  this  fe&ion.  Nor  is  it 
poffible,  that  fuch  deformities  could  be  produced  by  the  growth 
of  two  embryons,  or  living  filaments  ;  which  fhould  afterwards 
adhere  together  ;  as  the  head  and  tail  part  of  different  polypi 
are  faid  to  do  ((Blumenbach  on  Generation  Cadell,  London)  ; 
lince  in  that  cafe  one  embryon,  or  living  filament,  muft  have 
begun  to  form  one  part  firft,  and  the  other  another  part 
firft.  But  fuch  monftrous  conformations  become  lefs  difficult 
to  comprehend,  when  they  are  confidered  as  an  efle£l  of  the  im- 
agination, as  before  explained,  on  the  living  filament  at  the  time 

of 


SECT.  XXXIX.  6.  5.          GENERATION.  4 1 1 

of  its  fecretion  ;  and  that  fuch  duplicature  of  limbs  was  pro- 
duced by  accretion  of  new  parts,  in  confequence  of  propenfi- 
ties,  or  animal  appetencies,  thus  acquired  from  the  male  parent. 

For  inftance,  I  can  conceive,  if  a  turkey-cock  {hould  behold  a 
rabbit,  or  a  frog,  at  the  time  of  procreation,  that  it  might  hap- 
pen, that  a  forcible  or  even  a  pleafurable  idea  of  the  form  of  a 
quadruped  might  fo  occupy  his  imagination,  as  to  caufe  a  tenden- 
cy in  the  nafcent  filament  to  refemble  fuch  a  form,  by  the  appo- 
fition  of  a  duplicature  of  limbs.  Experiments  on  the  production 
of  mules  and  monfters  would  be  worthy  the  attention  of  a  Spal- 
lanzani,  and  might  throw  much  light  upon  the  fubjedr,  which 
at  prefent  muit  be  explained  by  conjedural  analogies. 

The  wonderful  effect  of  imagination,  both  in  the  male  and 
female  parent,  is  (hewn  in  the  production  of  a  kind  of  milk  in 
the  crops  both  of  the  male  and  female  pigeons  after  the  birth  of 
their  young,  as  obferved  by  Mr  Hunter,  and  mentioned  before. 
To  this  fhould  be  added,  that  there  are  fome  inftances  of  men 
having  had  milk  fecreted  in  their  breads,  and  who  have  given 
fuck  to  children,  as  recorded  by  Mr.  BufFon.  This  effect 
of  imagination,  of  both  the  male  and  female  parent,  feems  to 
have  been  attended  to  in  very  early  times  ;  Jacob  is  faid  riot  on- 
ly to  have  placed  rods  of  trees,  in  part  dripped  of  their  bark,  fo 
as  to  appear  fpotted,  but  alfo  to  have  placed  fpotted  lambs  before 
the  flocks,  at  the  time  of  their  copulation.  Genefis,  chap.  xxx. 
verfe  40. 

5.  In  refpedt  to  the  imagination  of  the  mother,  it  is  diffi- 
cult to  comprehend,  how  this  can  produce  any  alteration  in  the 
fetus,  except  by  affefting  the  nutriment  laid  up  for  its  firft  re- 
ception, as  defcribed  in  No.  V.  2.  of  this  feclion,  or  by  affecl- 
ing  the  nourifhment  or  oxygenation  with  which  fhe  fupplies  it 
afterwards.  Perpetual  anxiety  may  probably  affect  the  fecre- 
tion of  the  liquor  amnii  into  the  uterus,  as  it  enfeebles  the 
whole  fyftem  ;  and  fudden  fear  is  a  frequent  caufe  of  mifcar- 
riage  ;  for  fear,  contrary  to  joy,  decreafes  for  a  time  the  adlion 
of  the  extremities  of  the  arterial  fyftem  ;  hence  fudden  pale- 
nefs  fucceeds,  and  a  fhrinking  or  contraction  of  the  veflels  of 
the  ikin,  and  other  membranes.  By  this  circumftance,  I  im- 
agine, the  terminations  of  the  placental  veflels  are  detached 
from  their  adhefions,  or  infer tions,  into  the  membrane  of  the 
uterus  ;  and  the  death  of  the  child  fucceeds,  and  confequent 
mifcarriage. 

Of  this  I  recollect  a  remarkable  inftance,  which  could  be  af- 
cribed  to  no  other  caufe,  and  which  I  fhall  therefore  relate  in 
few  words.  A  healthy  young  woman,  about  twenty  years  of 
age,  had  been  about  five  months  pregnant,  and  going  down  in- 
to 


412  GENERATION.        SECT.  XXXIX   6.  6. 

to  her  cellar  to  draw  fome  beer,  was  frighted  by  a  fervant  boy 
darting  up  from  behind  the  barrel,  where  he  had  concealed 
himfelf  with  defign  to  alarm  the  maid-fervant,  for  whom  he 
miftook  his  midrefs.  She  came  with  difficulty  up  Hairs,  began 
to  flood  immediately,  and  mifcarried  in  a  few  hours.  She  has 
fince  borne  feveral  children,  nor  ever  had  any  tendency  to  mif- 
carryof  any  of  them. 

In  refpect  to  the  power  of  the  imagination  of  the  male  over 
the  form,  colour,  and  fex  of  the  progeny,  the  following  in- 
ftances  have  fallen  under  my  obfervation,  and  may  perhaps  be 
found  not  very  unfrequent,  if  they  were  more  attended  to.  I 
am  acquainted  with  a  gentleman,  who  has  one  child  with  dark 
hair  and  eyes  ;  though  his  lady  and  himfelf  have  light  hair 
and  eyes  ;  and  their  other  four  children  are  like  their  parents. 
On  obferving  this  diflimilarity  of  one  child  to  the  others  he 
allured  me,  that  he  believed  it  was  his  own  imagination,  that 
produced  the  difference  ;  and  related  to  me  the  following  ftory. 
He  faid,  that  when  his  lady  lay  in  of  her  third  child,  he  became 
attached  to  a  daughter  of  one  of  his  inferior  tenants,  and  offer- 
ed her  a  bribe  for  her  favours  in  vain  ;  and  afterwards  a  greater 
bribe,  and  was  equally  unfuccefsful  ;  that  the  form  of  this  girl 
dwelt  much  in  his  mind  for  fome  weeks,  and  that  the  next  child, 
which  was  the  dark- eyed  young  lady  above  mentioned,  was  ex- 
ceedingly like,  in  both  features  and  colour^  to  the  young  woman 
who  refuted  his  addrefles. 

To  this  inftance  I  muft  add,  that  I  have  known  two  families, 
in  which,  on  account  of  an  intailed  eftate  in  expectation,  a  male 
heir  was  moft  eagerly  defired  by  the  father  ;  and  on  the  con- 
trary, girls  were  produced  to  the  feventh  in  one,  and  to  the  ninth 
in  another  ;  and  then  they  had  each  of  them  a  fon.  I  conclude, 
that  the  great  defire  of  a  male  heir  by  the  father  produced  rath- 
er a  difagreeable  than  an  agreeable  fenfation  ;  and  that  his  ideas 
dwelt  more  on  the  fear  of  generating  a  female,  than  on  the  pleaf- 
urabie  fenfations  or  ideas  of  his  own  male  form  or  organs  at  the 
time  of  copulation,  or  of  the  fecretion  of  the  femen  ;  and  that 
hence  the  idea  of  the  female  character  was  more  prefent  to  his 
mind  than  that  of  the  male  one  •,  till  at  length  in  defpair  of  gen- 
erating a  male  thefe  ideas  ceafed,  and  thofe  of  the  male  charac- 
ter prefided  at  the  genial  hour. 

6.  Hence  I  conclude,  that  the  acl:  of  generation  cannot  ex- 
ift  without  being  accompanied  with  ideas,  and  that  a  man  mull 
have  at  that  time  either  a  general  idea  of  his  own  male  form,  or 
of  the  form  of  his  male  organs  j  or  an  idea  of  the  female  form, 
or  of  her  organs  ;  and  that  this  marks  the  fex,  and  the  peculiar 
refemblances  of  the  child  to  either  parent.  From  whence  it 

would 


SECT.  XXXIX.  7.  i.        GENERATION.  413 

would  appear,  that  the  phalli,  which  were  hung  round  the  necks 
of  the  Roman  ladies,  or  worn  in  their  hair,  might  have  effect 
in  producing  a  greater  proportion  of  male  children  ;  and  that 
the  calipsedia,  or  art  of  begetting  beautiful  children,  and  of  pro- 
creating either  males  or  females,  may  be  taught  by  affecting  the 
imagination  of  the  male-parent ;  that  is,  by  the  fine  extremities 
of  the  feminal  glands  imitating  the  actions  of  the  organs  of  fenfe 
either  of  fight  or  touch.  But  the  manner  of  accomplifhing  this 
cannot  be  unfolded  with  fufficient  delicacy  for  the  public  eye  \ 
but  may  be  worth  the  attention  of  thofe,  who  are  ferioufly  in- 
tereited  in  the  procreation  of  a  male  or  female  child. 

Recapitulation. 

VII.  i.  A  certain  quantity  of  nutritive  particles  are  produ- 
ced by  the  female  parent  before  impregnation,  which  require 
no  further  digeilion,  fecretion,  or  oxygenation.  Such  are  feen 
in  the  unimpregnated  eggs  of  birds,  and  in  the  unimpregnated 
feed-vellels  of  vegetables. 

2.  A  living  filament  is   produced    by  the  male,  which  being 
inferted  amidit  thefe  firft  nutritive  particles,   is  ftimulated  into 
action  by  them  ;   and  in  confequence  of  this  action,  fome  of  the 
nutritive  particles  are  embraced,  and  added  to  the  original  liv- 
ing filament ;  in  the  fame  manner  as  common  nutrition  is  per- 
formed in  the  adult  animal. 

3.  Then  this  new  organization,  or  additional  part,  becomes 
ftimulated  by  the  nutritive  particles  in  its  vicinity,  and  fenfation 
is  now  fuperadded  to  irritation  ;  and  other  particles  are  in  con- 
fequence embraced,  and  added  to  the  living  filament  ;  as  is  feen 
in  the  new  granulations  of  flefh  in  ulcers. 

By  the  power  of  affbciation,  or  by  irritation,  the  parts  already 
produced  continue  their  motions,  and  new  ones  are  added  by 
fefifation,  as  above  mentioned  ;  and  laftly  by  volition,  which 
hit  fenforial  power  is  proved  to  exift  in  the  fetus  in  its  maturer 
age,  becaufe  it  has  evidently  periods  of  activity  and  of  fleeping  \ 
which  laft  is  another  word  for  a  temporary  fufpenfion  of  volition. 

The  original  living  filament  may  be  conceived  to  poifefs  a 
power  of  repulfmg  the  particles  applied  to  certain  parts  of  it,  as 
well  as  of  embracing  others,  which  (limulate  other  parts  of  it  ; 
as  thefe  powers  exili  in  different  parts  of  the  mature  animal ; 
thus  the  mouth  of  every  gland  embraces  the  particles  of  fluid, 
which  fuit  its  appetency  ;  and  its  excretory  duc~l  repulfes  thofe 
particles,  which  are  difagreeable  to  it. 

4.  Thus  the  outline    or  miniature  of  the  new  animal  is  pro- 
duced gradually,  but  in  no  great  length  of  time  •,  becaufe  the 

original 


4  M  GENERATION.        SECT.  XXXIX.  7.  5. 

original  nutritive  particles  require  no  previous  preparation  by  di- 
geition,  fecretion,  and  oxygenation  :  but  require  limply  tbe  fe- 
k&ion  and  appofition,  which  is  performed  by  the  living  fila- 
ment. Mr.  Blumenbach  fays,  that  he  pofTeffes  a  human  fetus 
of  only  five  weeks  old,  which  is  the  fize  of  a  common  bee,  and 
has  all  the  features  of  the  face,  every  finger,  and  every  toe  com- 
plete ;  and  in  which  the  organs  of  generation  arediftintily  feen. 
P.  76.  In  another  fetus,  whofe  head  was  not  larger  than  a  pea, 
the  whole  of  the  bafis  of  the  fkull  with  all  its  deprefiions,  aper- 
tures, and  prccefTes,  were  marked  in  the  mod  (harp  and  diftinft 
manner,  though  without  any  oflification.  Ib. 

5.  In  fome  cafes  by  the  nutriment  originally  depofited  by  the 
mother  the    filament  acquires  parts  not  exactly  fimilar  to  thofe 
of  the  father,  as  in  the  production  of  mules  and  mulattoes.     In 
other  cafes,  the  deficiency  of  this  original  nutriment  caufes  defi- 
ciencies of  the  extreme  parts  of  the  fetus,  which  are  laft  form- 
ed, as  the   fingers,  toes,  lips.     In  other  cafes,  a  duplicature   of 
limbs,  is  caufed  by  the  fuperabundance  of  this  original  nutritive 
fluid,  as   in  the   double  yolks  of  eggs,  and  the  chickens  from 
them  with  four  legs  and  four  wings,     But  the  production  of 
other  monfters,  as  thofe  with  two  heads,  or  with  parts  placed  in 
wrong  fituations,  feems  to  arife  from  the  imagination  of  the 
father  being  in  fome  manner  imitated  by  the  extreme  veflels  of 
the  feminal  glands  ;  as  the  colours  of  the  fpots  on  eggs,  and  the 
change  of  the  colour  of  the  hair  and  feathers  of  animals  by  do- 
meftication,  may  be  caufed  in  the  fame  manner  by  the  imagina- 
tion of  the  mother. 

6.  The  living  filament  is  a  part  of  the  father,  and  has  there- 
fore certain  propenfities,  or  appetencies,  which  belong  to  him  ; 
which  may  have  been  gradually  acquired  during  a  million  of 
generations,  even  from  the  infancy  of  the  habitable  earth  ;  and 
which  now   poflefles  fuch  properties,  as  would  render,  by  the 
appofition  of  nutritious  particles,  the  new  fetus  exactly  fimilar 
to  the  father  ;  as  occurs  in   the  buds  and  bulbs  of  vegetables, 
and  in  the  polypus,  and  tsenia,  or  tape-worm.     But  as  the  firft 
nutriment  is  fuppliedby  the  mother,and  therefore  refembles  fuch 
nutritive  particles,  as  have  been  ufed  for  her  own  nutriment  or 
growth,  the  progeny  takes  in  part  the  likenefs  of  the  mother. 

Other  fimilarities  of  the  excitability,  or  of  the  form  of  the 
male  parent,  fuch  as  the  broad  or  narrow  fhoulders,  or  fuch  as 
conftitute  certain  hereditary  difeafes,  as  fcrofula,  epilepfy,  in- 
fancy, have  their  origin  produced  in  one  or  perhaps  two  gene- 
rations ;  as  in  the  progeny  of  thofe  who  drink  much  vinous 
fpirits  ;  and  thofe  hereditary  propenfities  ceafe  again,  as  I  have 
obferved,  if  one  or  two  fober  generations  fucceed  j  otherwife 
the  family  becomes  extinft.  This 


SEcr.XXXlX.7-5-        GENERATION.  417 

This  living  filament  from  the  father  is  alfo  liable  to  have  its 
propenfities,  or  appetencies,  altered  at  the  timeof  its  production 
by  the  imagination  of  the  male  parent  ;  the  extremities  of  the 
feminal  glands  imitating  the  motions  of  the  organs  of  fenfe  ; 
and  thus  the  fex  of  the  embryon  is  produced ;  which  may  be 
thus  made  a  male  or  a  female  by  affecting  the  imagination  of 
the  father  at  the  time  of  impregnation.  See  Seel.  XXXIX.  6. 
3.  and  7. 

7.  After  the  fetus  is  thus  completely  formed  together  with 
its  umbilical  veffels  and  placenta,  it  is  now  fupplied  with  a  dif- 
ferent kind  of  food,  as  appears  by  the  difference  of  confiftency 
of  the  different  parts  of  the  white  of  the  egg,  and  of  the  liquor 
amnii,  for  it  has  now  acquired  organs  for  digeftion  or  fecretion, 
and  for  oxygenation,  though  they  are  as  yet  feeble  ;  which  can 
in  fome  degree  change,  as  well  as  feledt  the  nutritive  particles, 
which  are  now  prefented  to  it.  But  may  yet  be  affected  by  the 
deficiency  of  the  quantity  of  nutrition  fupplied  by  the  mother, 
or  by  the  degree  of  oxygenation  fupplied  to  its  placenta  by  the 
maternal  blood. 

The  augmentation  of  the  complete  fetus  by  additional  particles 
of  nutriment  is  not  accomplimed  by  diftenrion  only,  but  by  ap- 
pofition  to  every  part  both  external  and  internal ;  each  of  which 
acquires  by  animal  appetencies  the  new  addition  of  the  particles 
which  it  wants.  And  hence  the  enlarged  parts  are  kept  fimilar 
to  their  prototypes,  and  may  be  faid  to  be  extended  ;  but  their 
extenfion  muft  be  conceived  only  as  a  neceffary  confequence  of 
the  enlargement  of  all  their  parts  by  appofition  of  new  particles. 

Hence  the  new  appofition  of  parts  is  not  produced  by  capilla- 
ry attraction,  becaufe  the  whole  is  extended  ;  whereas  capillary 
attraction  would  rather  tend  to  bring  the  fides  of  flexible  tubes 
together,  and  not  to  diftend  them.  Nor  is  it  produced  by 
chemical  affinities,  for  then  a  folution  of  continuity  would  fuc- 
ceed,  as  when  fugar  is  diffolved  in  water ;  but  it  is  produced  by 
an  animal  procefs,  which  is  the  confequence  of  irritation,  or 
fenfation  ;  and  which  may  be  termed  animal  appetency. 

This  is  further  evinced  from  experiments,  which  have  been 
instituted  to  (hew,  that  a  living  mufcle  of  an  animal  body  re- 
quires greater  force  to  break  it,  than  a  fimilar  mufcle  of  a  dead 
body.  Which  evinces,  that  befides  the  attraction  ofcohefion, 
which  all  matter  poffeffes,  and  befides  the  chemical  attraction* 
of  affinities,  which  hold  many  bodies  together,  there  is  an  ani- 
mal adhefion,  which  adds  vigour  to  thefe  common  laws  of  the 
inanimate  world. 

8.  At  the  ^nativity  of  the  child  it  depofites  the  placenta  or 
gills,  and  by  expanding  it  lungs  acquires  more  plentiful  oxyge- 
nation 


416  GENERATION.        SECT.  XXXIX.  7. 8, 

nation  from  the  currents  of  air,  which  it  muft  now  continue 
perpetually  to  refpire  to  the  end  of  its  life  ;  as  it  now  quits  the 
liquid  element,  in  which  it  was  produced,  and  like  the  tadpole, 
when  it  changes  into  a  frog,  becomes  an  aerial  animal. 

9.  As  the  habitable  parts  of  the  earth  have  been,  and  con* 
tinue  to  be,  perpetually  increafing  by  the  production  of  fea- 
fhells  and  corallines,  and  by  the  recrements pf  other  animals, 
and  vegetables ;  fo  from  the  beginning  of  the  exiitence  of  this 
terraqueous  globe,  the  animals,  which  inhabit  it,  have  coniiant- 
3y  improved,  and  are  (till  in  a  ftate  of  progrefTive  improvement. 

This  idea  of  the  gradual  generation  of  all  things  feems  to 
have  been  as  familiar  to  the  ancient  philofophers  as  to  the  mod- 
ern ones  j  and  to  have  given  rife  to  the  beautiful  hieroglyphic 
figure  of  the  K^rovem  or  firfi  great  egg,  produced  by  NIGHT, 
that  is,  whofe  origin,  is  involved  in  obfcurity,  and  animated  by 
Sg«5,  that  is,  by  DIVINE  LOVE  ^from  whence  proceeded  all  things 
which  exift. 

Appendix. 

VIII.  i.  Since  the  former  publication  of  the  preceding  Sec- 
tion on  Generation,  I  have  been  induced  in  my  treatife  on  Phyt- 
ologia,  to  give  more  attention  to  the  lateral  or  folitary  genera- 
tion of  vegetables  in  the  production  of  their  buds,  hoping  from 
thence  to  throw  ibme  light  on  their  fexual  generation  in  the  pro- 
duction of  feeds  ;  and  in  confequence  on  the  propagation  of 
more  perfect  animals,  which  I  (hall  here  relate,  believing  that 
it  may  intereft  the  philosophical  reader,  obferving  only,  that  by 
the  vegetable  facts  here  attended  to,  I  am  now  induced  to  be- 
lieve, that  the  embryons  of  complicate  animal  and  vegetable 
bodies  are  not  formed  from  a  fingle  filament  as  above  delivered  ; 
but  that  their  ftructure  commences  in  many  parts  at  the  fame 
time,  though  it  is  probable,  that  the  moft  fimple  or  firft  exordi- 
um of  animation  was  begun  by  a  fingle  filament,  and  continues 
to  do  fo  in  the  fpontaneous  production  of  the  fmallelt  njicro- 
fcopic  animals,  which  do  not  appear  to  have  been  generated 
by  other  animalcula  fimilar  to  themfelves,  as  further  fpoken  of 
in  No.  ii.  5.  or  this  Section. 

i.  It  is  Ihewn  at  large  in  the  work  above  mentioned,  that 
every  bud  of  a'tree  is  an  individual  vegetable,  and  confifts  of  the 
plumulaor  leaf  at  its  fummit,  of  a  long  caudex  extending  from 
this  fummit  downwards  to  the  earth,  forming  a  filament  of  the 
bark,  and  laftly  of  radicles  beneath  the  foil  :  it  is  alfo  fhewn, 
that  every  bud  pofTefles  the  power  of  germination  or  reproduc- 
tion, not  only  in  the  axilla  of  the  leaf,  which  is  moft  common, 

but 


SECT.  XXXIX  8.  i.  GENERATION.  417 

but  from  any  part  of  the  lon£  caudex  gemmae  above  mentioned, 
as  appears  from  new  buds  fpringing  out  from  any  part  of  the 
bark,  when  the  top  of  a  branch  is  cut  off 

Now  if  a  fcion  of  a  nonpareil  apple  be  ingrafted  on  a  crab 
flock,  and  a  golden  pippin  be  ingrafted  on  the  nonpareil,  what 
happens  ? — The  caudex  of  the  bud  of  the  golden-pippin  confiils 
of  its  proper  abforbent  vefleis,  arteries,  and  veins,  till  it  reaches 
down  to  the  nonpareil  (lock ;  and  then  the  continuation  of  its 
caudex  downwards  confitls  of  veffcls  fimilar  to  thofe  of  the  non- 
pareil ;  and  when  its  caudex  defcends  dill  lower,  it  confifts  of 
veffels  fimilar  to  thofe  of  the  crab-flock. 

The  truth  of  this  is  fhewn  by  two  circumflances  •,  firft,  be- 
caufe  the  lower  parts  of  this  compound  tree  will  occafionally  put 
forth  buds  fimilar  to  the  original  (lock.  And  fecondly,  be- 
caufe  in  fome  ingrafted  trees,  where  a  quick-growing  fcion 
has  been  inferted  into  a  flock  of  flower  growth,  as  is  often  feen 
in  old  cherry-trees,  the  upper  part  of  the  trunk  of  the  tree  has 
become  of  almofl  double  the  diameter  of  the  lower  part  Both 
which  occurences  fhew,  that  the  lower  part  of  the  trunk  of  the 
tree  continues  to  be  of  the  fame  kind,  though  it  mii'l  have  been 
fo  repeatedly  covered  over  with  new  circles  of  wood,  bark,  and 
cuticle. 

Now  as  the  caudex  of  each  bud,  which  pafies  the  whole 
length  of  the  trunk  of  the  tree,  and  forms  a  communication  from 
the  upper  part  of  plumula,  to  the  lower  part  or  radicle,  mud 
confift  in  thefe  doubly  ingrafted  trees  of  three  different  kinds  of 
caudexes,  refembling  thofe  of  the  different  flocks  or  fcions  ;  we 
acquire  a  knowledge  of  what  may  be  termed  a  lateral  or  pater- 
nal mule,  in  contradiflindlion  to  a  fexual  mule.  For  as  in  thefe 
trees  thus  combined  by  ingraftment  every  bud  has  the  upper 
part  of  its  caudex  that  of  a  golden-pippin,  the  middle  part  of  it 
that  of  a  nonpareil,  and  the  lower  part  of  it  that  of  a  crab  ;  if 
thefe  caudexes,  which  conftitute  the  filaments  of  the  bark  could 
be  feparated  intire  from  the  tree  with  their  plumules  and  radi- 
cles, they  would  exhibit  fo  many  lateral  or  paternal  mules,  con- 
fitting  of  the  connected  parts  of  their  three  parents ;  the  plu- 
mula belonging  to  the  upper  parent,  and  the  radicle  to  the  low- 
er one,  and  the  triple  caudex  to  them  all. 

A  feparation  of  thefe  buds  from  the  parent  plant  is  faid  to 
have  been  obferved  by  Mr.  Blumenbach,  in  the  conferva  font!- 
nalis,  a  vegetable  which  confilts  of  fmall  Ihort  flender  threads, 
which  grow  in  our  fountains,  and  fix  their  roots  in  the  mud. 
He  obferved  by  magnifying  glafles,  that  the  extremities  of  the 
threads  fwell,  and  form  firuli  tubera  or  heads  ;  which  gradually 
feparate  from  the  parent  threads,  attach  themfclves  to  the 

VOL.  I.  F  F  f  ground. 


4i 8  GENERATION.        SECT.  XXXIX.  8.  2, 

groud,  and  become  per feft  vegetables  ;  the  whole  progrefs  of 
their  formation  can  be  obferved  in  forty-eight  hours.  Obfer- 
vations  on  plants  by  Von  Uflar.  Creech,  Edinb. 

2.  The  lateral  propagation  of  the  polypus  found  in  our  ditches 
in  July,  but  more  particularly  that  of  the  hydra  ftentorea,  is  won- 
derfully analogous  to  the  above  idea  of  the  lateral  generation  of 
vegetables.     The  hydra  ftentorea,  according  to  the  account  of 
Monf.  Trembly,  multiplies  itfelf  by  fplitting  lengthwife  ;  and 
in  twenty-four  hours  thefe  divifions,  which  adhere  to  a  common 
pedicle,  refplit,  and  form  four  diftinft  animals.     Thefe  four  in 
an  equal  time  fplit  again,  and  thus  double  their  number  daily  ; 
till  they  acquire  a  figure  fomewhat  refembling  a  nofegay      The 
young  animals  afterwards  feparate  from  the  parent,  attach  them- 
felves  to  aquatic  plants,  and  give  rife  to  new  colonies. 

Another  curious  animal  fa£b  is  related  by  Blumenbach  in  his 
Treatife  on  Generation  concerning  the  frefh  water  polypus.  He 
cut  two  of  them  in  halves,  which  were  of  different  colours,  and 
applying  the  upper  part  of  one  to  the  lower  part  of  the  other  by 
means  of  a  glafs  tube,  and  retaining  them  thus  for  fome  time  in 
contaft  with  each  other,  the  two  divided  extremities  united,  and 
became  one  animal.  The  facile  union  of  the  divided  halves  of 
different  polypi  is  alfo  afferted  by  Mr.  Adams.  Treatife  on 
Microfcopes. 

The  intelligent  reader  has  already  anticipated  me  in  applying 
thefe  wonderful  modes  of  lateral  animal  reproduction  and  con- 
jundlion,  to  the  lateral  propagation  and  ingraftment  of  vegeta- 
bles. The  junftion  of  the  head  part  of  one  polypus  to  the  tail- 
part  of  another  is  exactly  reprefented  by  the  ingraftment  of  a 
fcion  on  the  ftock  of  another  tree,  the  plumula  or  apex  of  each 
bud  with  the  upper  part  of  its  caudex  joins  to  the  long  caudex 
of  the  ftock,  which  pafling  down  the  trunk  terminates  in  the 
radicles  of  it.  And  if  this  compound  vegetable  could  be  fepa- 
rated  longitudinally  from  the  other  long  filaments  of  the  bark  in 
its  vicinity,  like  the  fibres  of  the  bark  of  the  mulberry  tree  pre- 
pared at  Otaheite,  or  as  the  bark  of  hemp  and  flax  are  pre- 
pared in  this  country,  as  the  young  ones  of  the  hydra  ftentorea 
feparate  from  their  parents,  it  might  claim  the  name  of  a  lateral 
or  paternal  mule,  as  above  mentioned. 

3.  It  hence  appears,  that  every  new  bud  of  a  tree,  where  two 
fcions  have  been  inferted  over  each  other  on  a  ftock,  if  it  could 
be  feparated  from  the  plume  to  the  radicle,  muft  confift  of  three 
different  kinds  of  caudex  ;  and  might  therefore  be  called  a  triple 
lateral  mule.     And  that  hence  it  follows,  that  every  part  of  this 
new  triple  caudex  muft  have  been  feparated  or  fecreted  laterally 
from  the  adjoining  part  of  the  trunk  of  the  tree  ;  and  that  it 

could 


SECT.  XXXIX.  8.  4.        GENERATION.  419 

could  not  be  formed,  as  I  formerly  believed,  from  the  roots  of 
the  plume  of  the  bud  defcending  from  the  upper  part  of  the  cau- 
dex  of  it  to  the  earth.  A  circumftance  of  great  importance  in 
the  inveftigation  of  the  curious  fubject  of  the  lateral  generation 
of  vegetables  and  of  infects. 

One  might  hence  fufpect,  that  if  Blumenbachhad  attended  to 
the  propagation  of  the  polypus,  which  he  had  compofed  of  two 
half  polypi,  that  the  young  progeny  might  have  poffeffed  two 
colours  refembling  the  compound  parent,  like  the  different  cau- 
dexes  of  ingrafted  trees  ;  an  experiment  well  worthy  repeated 
observation. 

4.  Another  animal  fact  ought   alfo  to  be  here    mentioned, 
that  many  infects,  as  common  earth  worms  as  well  as  the  poly- 
pus, are  faid  to  poflefs  fo  much  life  throughout  a  great  part  of 
their  fyftem ;    that  they  may   be  cut  into  two  or  more    pieces 
without  deftroying  them  ;  as  each  piece  will  acquire  a  new  head, 
or  a  new  tail,  or  both,    and  the  infect  will   thus  become  multi- 
plied !  How  exactly  this  is  refembled  by  the  long  caudex  of  the 
buds  of  trees  j    which  poflefs  fuch  vegetable  life  from  one  ex- 
tremity to  the  other,  that  when  the  head  or  plume  is  lopped  off, 
it  can  produce  a  new  plume,   and  when  the  lower  part  is  cut 
off,  it  can  produce  new  radicles  j  and  may  be  thus  wonderfully 
multiplied  ! 

This  curious  vegetable  phenomenon  is  worthy  our  attention 
and  remembrance  ;  for  as  each  filament  of  the  new  bark  of  a 
tree  conftitutes  a  caudex  of  an  embryon  bud  -,  when  the  fum- 
mit  of  a  twig  is  lopped  off,  which  contained  the  plumules  or  em- 
bryon leaves  of  many  of  them  j  each  embryon  caudex  can  gen- 
erate new  plumules  or  embryon  leaves  j  and  new  radicles,  when 
the  lower  part  of  a  twig  is  cut  off,  and  the  upper  part  planted  ; 
which  demonftrates,  that  the  primary  parts  of  a  vegetable  em- 
bryon may  produce  fecondary  parts  ;  and  that  hence  it  is  not 
neceffary,  that  the  whole  of  an  animal  fetus  fhould  be  formed 
at  the  fame  time. 

5.  Hence  we   acquire  fome  new  and   important  ideas  con- 
cerning the  lateral  generation  of  vegetables,  and  which  may 
probably  contribute  to  elucidate  their  fexual  generation.    Thefe 
are,  firft,  that  the  parts  of  the  long  caudex  of  each  new  bud  of 
an  ingrafted  tree,  and  confequently  of  all  trees,    are  feparated 
or  fecreted   from    the  correfpondent  or  adjoining  parts  of  the 
long  caudex  of  the  lail  year's  bud,  which  was  its  parent.      And 
not  tjiat  it  confifts  of  the  roots  of  each  new  bud  (hot  down  from 
the  plumula  or  apex  of  it ;    as   I  formerly  fuppofecl.     And    that 
thefe  various  molecules  or   fibrils  fecreted   from  >the  caudex  of 
the  lad  year's  buds  adjoin  and  grow  together  beneath  the  cuticle 

of 


420  GENERATION.          SECT.  XXXIX.  8.6. 

of  the  trunk  of  the  tree  ;  the  upper  ones  forming  the  plumula 
of  the  new  bud,  which  is  its  leaf  or  lungs  to  acquire  oxygen 
from  the  atmoiphere  ;  and  the  lower  ones  forming  the  radicles 
of  it,  which  are  abibrbent  veiTels  to  acquire  nutriment  from 
the  earth. 

Secondly,  that  every  part  of  the  caudex  of  an  ingrafted  tree, 
and  confequently  of  all  trees,  can  generate  or  produce  a  new 
plumula,  when  the  upper  part  of  it  is  flrangulated  with  a  wire 
or  cut  off ;  or  otherwife  when  it  is  fupplied  more  abundantly 
with  nutriment,  ventilation,  and  light.  And  that  each  of  thtie 
new  buds  thus  produced  refembles  that  part  of  the  flock  in  com- 
pound trees,  where  it  arifes.  Thus  in  the  triple  tree  above 
mentioned  a  bud  from  the  upper  part  of  the  long  caudexes, 
-which  form  the  filaments  of  the  bark,  would  become  a  gokSen- 
pippin  branch,  a  bud  from  the  middle  part  of  them  would 
become  a  nonpareil  branch,  and  a  bud  from  the  lower  part  a 
crab  branch. 

Thirdly,  another  wonderful  property  of  this  lateral  mule 
progeny  of  trees  compounded  by  irigraftment  confifls  in  this, 
that  the  new  mule  may  confifl  of  parts  from  three  or  four  or 
many  parents  ;  when  io  many  different  (cions  are  ingrafted  on 
each  other,  whence  a  queftion  may  arife,  whether  a  mixture  of 
two  kinds  of  anther-dud  previous  to  its  application  to  the  flig- 
ma  of  flowers  might  not  produce  a  threefold  mule  partaking  of 
the  likenefs  of  both  the  males  ? 

6.  On  this  nice  fubje£l  of  reproduction,  fo  far  removed  from 
common  apprehenfion,  the  patient  reader  will  excufe  a  more 
prolix  inveftigation.  The  attraction  of  all  matter  to  the  centres 
of  the  planets,  or  of  the  fun,  is  termed  gravitation,  thaf  of  par- 
ticular bodies  to  each  other  is  generally  called  chemical  affinity  j 
to  which  the  attraclions  belonging  to  electricity  and  magnetilm 
appear  to  be  allied. 

In  thefe  latter  kinds  of  attraclion  two  circum (lances  feem  to 
be  required,  firit,  the  power  to  attra£l  poflefled  by  one  oi  the 
bodies,  and  fecondly,  the  aptitude  to  be  attracted  poflefled  by 
the  other.  Thus  when  a  magnet  attracts  iron,  it  may  be  faid 
to  poflTefb  a  fpecific  tendency  ro  unite  with  iron ;  and  the  iron 
may  be  faid  to  poiTefs  a  fpecific  aptitude  to  be  united  with  the 
magnet.  The  former  appears  to  refide  in  the  magnet,  becaufe 
it  can  be  deprived  of  its  attractive  power,  which  can  alfo  be  reftor- 
ed  to  it.  And  the  iron  appears  to  poflefs  a  fpecific  aptitude  to  be 
united  with  the  magnet,  becaufe  no  other  metal  will  approach 
it.  In  the  fame  manner  a  rubbed  glafs  tube  or  a  rubbed  flick 
of  fealing  wax  may  be  faid  to  pofTefs  a  fpecific  tendency  to  unite 
with  a  light  draw,  or  hair,  and  the  flraw  or  hair  to  poflefs  a 

fpecific 


SECT.  XXXIX.  8. 7.       GENERATION.  421 

fpecific  aptitude  to  unite  with  the  rubbed  glafs  or  fealing  wax; 
becaufe  the  fpecific  attraction  to  the  rubbed  glafs  or  feaiing  wax 
can  be  withdrawn  or  rettored  ;  to  which  may  be  added,  that 
fome  chemical  combinations  may  arife  from  the  (ingle  attrac- 
tion of  one  body,  and  the  aptitude  to  be  attracted  of  another. 
Or  they  may  be  owing  to  reciprocal  attractions  of  the  two 
bodies,  as  in  what  is  termed  by  the  chemifts  double  affinity, 
which  is  known  to  be  fo  powerful  as  to  feparate  thole  bodies, 
which  are  held  together  by  the  fimple  attraction  probably  of 
one  of  them  to  the  other  ;  which  other  pofTeffes  only  an  apti- 
tude to  be  attracted  by  the  former. 

It  is  probable,  that  in  fome  of  the  mod  fimple  combinations 
of  the  particles  of  inanimate  matter,  two  of  them  may  be 
ftronglv  united  by  reciprocal  attractions  to  each  other ;  that  in 
other  fimple  combinations  two  particles  may  be  held  together, 
though  lefs  firmly,  by  the  attraction  of  one  and  the  aptitude  to  be 
attracted  of  the  other.  ThusI  fulpect  that  carbon  and  oxygen  rufli 
together  by  their  reciprocal  attractions  producing  explofion,  and 
being  afterwards  not  eafily  feparable  ;  while  azote  or  nitrogen  is 
lefs  nrmly  united  with  oxygen  by  the  attraction  of  one  of  them, 
and  only  the  aptitude  to  be  attracted  of  the  other.  If  this  cir- 
cum (lance  could  be  nicely  afcertained,  the  theory  of  chemical 
affinities  might  poffibly  advance  a  ftep  further  in  the  explana- 
tion of  fome  difficult  phenomena,  as  of  the  heat  generated  in 
the  explofion  of  various  materials,  with  which  oxygen  is  more 
loofely  united,  when  applied  to  ignited  carbon  ;  as  of  the  acid 
of  nitre,  and  feveral  metallic  oxydes  ;  as  well  as  of  the  general 
circumftances  of  combuftion  and  inflammation,  as  of  phofphb- 
rus  in  the  atmofphere,  and  of  oil  of  cloves  with  nitrous  acid. 

7.  The  above  account  of  the  tendencies  to  union  of  unor- 
ganized or  inanimate  matter  is  not  given  as  a  philofophical 
analogy,  but  to  facilitate  our  conceptions  of  the  adjunctions  or 
concretions  obfervabie  in  organized  or  animated  bodies  ;  which 
conftitute  their  formation,  their  nutrition,  and  their  growth. 
Thefe  may  be  divided  into  two  kinds  ;  firft  the  junction  or 
union  of  animated  bodies  with  inanimate  matter,  as  when  fruit 
or  flefh  is  fwallowed  into  the  ftomach,  and  becomes  abforbed 
by  the  lacleals  ;  and  the  fecond,  where  living  particles  coalefce 
or  concrete  together  ;  as  in  the  formation,  nutrition,  or  con- 
junftion  of  the  parts  of  living  animals. 

In  reipecl  to  the  former  the  animal  parts,  as  the  noftrils  and 
palate,  poffefs  an  appetency,  when  (limulated  by  the  fcent  and 
flavour  of  agreeable  food,  to  unite  themfelves  with  it ;  and  the 
inanimate  material  poflefles  an  aptitude  to  be  thus  united  with 
the  animal  organ.  The  fame  occurs,  when  the  food  is  fwal- 
lowed 


42 z  GENERATION.        SECT.  XXXIX.  8.  8. 

lowed  info  the  ftomach  ;  the  mouths  of  the  lafteal  veflels  be- 
ing agreeably  itimulated  poflefs  an  appetency  to  abforb  the  par- 
ticles of  the  digefting  mafs  ;  which  is  in  a  fituation  of  under- 
going chemical  changes,  and  poflefles  at  fome  period  of  them 
•an  aptitude  to  fbimulate,  and  to  be  united  with  the  mouths  of 
the  abforbent  lacleals. 

But  when  thefe  abforbed  particles  of  inanimate  matter  have 
been  circulated  in  the  blood,  they  feem    gradually    to  obtain  a 
kind  of  vitality  ;  whence  Mr.  John  Hunter,  and  I  believe  fome 
antient  philofophers,  and  the  divine  Mofes,  aliened,  that  the 
blood  is  alive  ;  that  is,  that  it  poflefles  fome   degree  of  organi- 
zation, or  other  properties,  different  from  thofe    of  inanimate 
matter ;   which  are  not  producible  by  any  chemical  procefs,  and 
which  ceafe  to  exift  along  with  the  life  of  the  animal.     Hence 
for  the  purpofe  of  nutrition  there  is  reafon  to  fufpe£t,  that  two 
circum (lances  are  neceflary,  both  dependent  upon  life,  and  con- 
fequent  activity  ;  thefe   are  firft  an  appetency  of   the  fibrils  of 
the  fixed  organization,  which  wants  nutrition  ;  and  fecondly   a 
propenfity  of  the  fluid   molecules  exifting  in  the  blood,  or  fe- 
creted  from  it,  to  unite  with  the  organ  now  flimulated  into  ac- 
tion.    So  that  nutrition  may  be  faid  to  be  efle&ed  by  the  em- 
brace or  coalefcence  of  the  fibrils,    which  poflefs  nutritive  appe- 
tencies, with  the  molecules,  which  pofiefs  nutritive  propenfities, 
or  in  other  words  of  particles,  which  poflefs  reciprocal  appeten- 
cies to  embrace  each  other. 

8.  If  the  philofopher,  who  thinks  on  this  fubjeft,  (hould  not 
be  inclined  to  believe,  that  the  whole  of  the  blood  is  alive,  he 
cannot  eafily  deny  life  to  that  part  of  it,  which  is  fecreted  by 
rhe  organs  of  generation,  and  conveys  vitality  to  the  new  em- 
bryon,  which  it  produces.  Hence  though  in  the  procefs  of  nu- 
trition the  activity  of  two  kinds  of  fibrils  or  molecules  may  be 
fufpecled,  yet  in  the  procefs  of  the  generation  of  a  new  vegeta- 
ble or  animal,  there  feems  great  reafon  to  believe,  that  both  the 
combining  and  combined  particles  are  endued  with  vitality  ; 
that  is,  with  fome  degree  of  organization  or  other  properties  not 
exifting  in  inanimate  matter,  which  we  beg  leave  to  denominate 
fibrils  with  formative  appetencies,  and  molecules  with  formative 
propenfnies-,  as  the  former  may  feem  to  poflefs  a  greater  degree 
of  organization  than  the  latter. 

And  thus  it  appears,  that  though  nutrition  may  be  conceived 
to  be  produced  by  the  animated  fibrils  ot  an  organized  part  be- 
ing (limulated  into  action  by  inanimate  molecules,  which  they 
then  embrace  ;  and  may  thus  be  popularly  compared  to  the 
fimple  attractions  of  chemiftry  ;  yet  that  in  the  production  of 
a  new  embryon,  whether  vegetable  or  animal,  both  the  fibrils 

with 


SECT.  XXXIX.  8. 9.         GENERATION.  423 

with  formative  appetencies  and  the  molecules  with  formative  pro- 
penfities  reciprocally  ftimulate  and  embrace  each  other,  and  in- 
ftantly  coalefce  ;  and  may  thus  popularly  be  compared  to  the  re- 
ciprocal attractions  of  fome  of  the  atoms  of  inanimate  matter, 
or  to  the  double  affinities  of  chemiftry.  But  there  are  animal 
fa&s,  which  may  be  compared  to  both  thefe,  and  are  thence 
more  philofophically  analogous  to  them  ;  and  thefe  are  the  two 
great  fupports  of  animated  nature,  the  pafiions  of  hunger  and  of 
love.  In  the  former  the  appetency  refides  only  in  the  ftomach, 
or  perhaps  in  the  cardia  ventriculi,  but  the  object  confilts  of  in- 
animate matter  ;  in  the  latter  there  exift  reciprocal  appetencies 
and  propenfities  in  the  male  and  female,  which  mutually  ex- 
cite them  to  embrace  each  other.  Two  other  animal  facb  are 
equally  analogous  ;  the  thirft,  which  refides  at  the  upper  end 
of  the  efophagus,  and  though  it  pofleffes  appetency  itfelf,  its  ob- 
ject is  inanimate  matters  ;  but  in  ladefcent  females,  when  they 
give  fuck  to  their  young,  there  exifts  a  reciprocal  appetency  in 
the  mother  to  part  with  her  milk,  and  in  the  young  offspring  to 
receive  it. 

This  then  finally  I  conceive  to  be  the  manner  of  the  produc- 
tion of  the  lateral  progeny  of  vegetables.  The  long  caudex  of 
an  exifting  bud  of  a  tree,  which  conflitutes  a  (ingle  filament  of 
the  prefent  bark,  is  furnilhed  with  glands  numerous  as  the  per- 
fpirative  or  mucous  glands  of  animal  bodies ;  and  that  thefe  are 
of  two  kinds,  the  one  fecreting  from  the  vegetable  blood  the  fi- 
brils with  formative  appetencies,  correfpondent  to  the  mafculine 
fecretion  of  animals  ;  and  the  other  fecreting  from  the  vegeta- 
ble blood  the  molecules  with  formative  propenfities,  correfpon- 
dent to  the  feminine  fecretion  of  animals,  and  then  that  both 
thefe  kinds  of  formative  particles  are  depofited  beneath  the  cu- 
ticle of  the  bark  along  the  whole  courfe  of  it,  and  inftamly  em- 
brace and  coalefce,  forming  a  new  caudex  along  the  fide  of  its 
parent,  with  vegetable  life,  and  with  the  additional  powers  of 
nutrition,  and  of  growth. 

9.  This  then  is  the  great  fecret  of  nature.  More  living 
particles,  fome  with  appetencies,  and  fome  with  propenfities, 
are  produced  by  the  powers  of  vitality  in  the  fabrication  of  the 
vegetable  blood,  than  are  neceflary  for  nutrition,  or  for  the  ref- 
toration  of  decompofing  organs.  Thefe  are  fecreted  by  differ- 
ent glands,  and  detruded  externally,  and  produce  by  their  -com- 
bination a  new  vital  organization  beneath  the  cuticles  of  trees 
over  the  old  one.  Thele  new  combinations  of  vital  fibrils  and 
molecules  acquire  new  appetencies,  and  fabricate  molecules 
with  new  propenfities  ;  and  thus  poflefs  the  power  of  forming 
the  leaf  or  lungs  at  one  extremity  of  the  new  caudex  ;  and  the 

radicles 


424  GENERATION.        SECT.  XXXIX.  8.  10, 

radicles  or  abforbent  veflels  at  the  other  end  ;  and  fome  of  them, 
as  in  the  central  buds,  which  terminate  the  branches,  finally 
form  the  fexual  organs  of  reproduction,  which  conftitute  the 
flower  ;  all  which  are  fecondary  parts  of  the  new  embryon  or 
fetus,  as  (hewn  in  number  9.  4.  of  this  fetlion. 

That  new  organizations  of  the  growing  fyftem  acquire  new 
appetencies  appears  from  the  produftion  of  the  paflion  for  gen- 
eration, as  foon  as  the  adapted  organs  are  complete,  and  alfo 
from  the  variation  of  the  palate,  or  defire  for  particular  kinds 
of  food,  as  we  advance  in  life,  as  from  milk  to  flefh  ;  thus  as  a 
popular  allufion,  not  as  a  philofophical  analogy,  we  may  again 
be  allowed  to  apply  to  the  combinations  of  chemifhy.  Where 
two  different  kinds  of  particles  unite,  as  acids  and  alkalis,  a 
third  Something  is  produced,  which  poflefles  attractions  diflimi- 
lar  to  thofe  of  either  of  them. 

And  that  new  organizations  form  new  molecules,  appears 
from  the  fecretions  of  the  feminal  and  uterine  glands,  when 
they  have  acquired  their  maturity  ;  and  from  the  pe£loral  ones 
of  laftefcent  females. 

10,  In  the  lateral  propagation  of  vegetable  buds,  as  the  fu- 
perfluous  fibrils  or  molecules,  which  were  fabricated  in  the 
blood,  or  detached  from  living  organs,  and  poflefs  nutritive  or 
formative  appetencies  and  propenfities;  and  which  were  more 
abundant,  than  were  required  for  the  nutrition  of  the  parent 
vegetable  bud,  when  it  had  obtained  its  full  growth,  were  fe- 
creted  by  innumerable  glands  on  the  various  parts  of  its  furface 
beneath  the  general  cuticle  of  the  tree,  and  there  embracing  and 
coalefcing,  form  a  new  embryon  caudex,  which  gradually  pro- 
duces a  new  plumula  and  radicles.  And  as  the  different  parts 
of  the  new  caudex  of  a  compound  tree  refemble  the  parts  of 
the  parent  caudex,  to  which  it  adheres,  this  important  circum- 
ftance  is  {hewn  beyond  all  doubt,  that  different  fibrils  or  mole- 
cules were  detached  from  different  parts  of  the  parent  caudex 
to  form  the  filial  one. 

So  in  the  fexual  propagation  of  vegetables  the  fuperfluous  liv- 
ing fibrils  or  molecules  detached  from  various  part?  of  the  fyf- 
tem, and  floating  in  the  blood,  appear  to  be  fecreted  from  it  by 
two  kinds  of  glands  only,  thofe  which  conftitute  the  anthers, 
and  thofe  which  conititute  the  pericarp  of  flowers.  By  the  for- 
mer I  fuppofe  the  fibrils  with  formative  appetencies  and  with 
nutritive  appetencies  to  be  fecreted  ;  and  by  the  latter  the  mole- 
cules with  formative  and  with  nutritive  propenfities.  Atter- 
wards,  that  thefe  fibrils  with  formative  and  nutritive  appeten- 
cies become  mixed  in  the  pericarp  of  the  flower  with  the  cor- 
refpondent  molecules  with  formative  and  nutritive  propenfities, 

and 


SECT.  XXXIX.  8.  n.        GENERATION.  425 

and  that  a  new  embryon  is  inftantly  produced  by  their  recipro- 
cal embrace  and  coalefcence. 

And  that  parts  of  this  new  organization  afterwards  acquire 
new  appetencies,  and  form  new  molecules,  and  thus  gradually 
produce  other  parts  of  the  growing  feed,  which  do  not  at  firft 
appear,  as  the  plumula,  radicles,  cuticle,  and  the  glands  of  re- 
production in  the  pericarp  and  anthers,  which  correfpond  in 
the  animal  fetus  to  the  lungs,  inteftines,  cuticle,  and  the  organs, 
which  diftinguifh  the  fexes,  and  are  their  parts  of  fecondary 
formation, 

If  fecondary  parts  of  a  vegetable  embryon  were  not  fabrica- 
ted from  the  primary  parts,  or  firft  rudiments  of  it,  the  flowers 
of  the  clafh  dicecia  of  Linnxus  could  nor  produce  both  male 
and  female  feeds,  as  the  male  and  female  organs  of  reproduction 
refide  on  different  plants.  For  as  the  male  plants  produce  buds 
fimilar  to  thcmielvcs,  which  may  be  termed  male  buds  ;  and 
the  female  plants  produce  buds  fimilar  to  themfelves,  which 
may  be  termed  female  buds,  it  would  feem  impoflible  for  the 
flowers  to  generate  female  feeJs  according  to  the  theory  of  re- 
production above  delivered.  As  the  male,  not  being  an  her- 
maphrodite, cannot  be  fuppofed  to  fecrete  any  fibrils  with  ap- 
petencies proper  to  produce  female  organs,  as  no  fach  can  ex- 
id  in  his  blood,  which  mult  therefore  be  fabricated  afterwards 
by  the  new  appetencies  acquired  by  the  new  organizations  of 
the  growing  embryon. 

n.  From  this  new  doctrine  of  a  three-fold  vegetable  mule 
by  lateral  propagation,  as  the  new  bud  of  a  tree,  which  has  had 
two  fcions  ingrafted  on  it  one  above  another  ;  in  which  it  is  in- 
conteftibly  (hewn,  that  different  fibrils  or  molecules  are  detach- 
ed from  different  parts  of  the  parent  caudex  to  form  the  filial 
one,  which  adheres  to  it ;  we  may  fafely  conclude,  as  it  is  de- 
ducible  from  the  ftrongeft  analogy,  that  in  the  production  of 
fexual  mules,  foine  parts  of  the  new  embryon  were  produced 
by,  or  detached  from,  fimilar  parts  of  the  parent,  which  they 
refemble.  And  that  as  thefe  fibrils  or  molecules  floated  in  the 
circulating  blood  of  the  parents,  they  were  collected  feparately 
by  appropriated  glands  of  the  male  or  female  j  and  that  fi- 
nally on  their  mixture  in  the  matrix  the  new  embryon  was  gen- 
erated, refembling  in  fome  parts  the  form  of  the  father,  and  in 
other  parts  the  form  of  the  mother,  according  to  the  quantity 
or  adivity  of  the  fibrils  or  molecules  at  the  time  of  their  con- 
junction 

And  laftly,  that  various  parts  of  the  new  organizations  after- 
wards acquired  new  appetencies,  and  formed  molecules  with 
new  propenfitiesj  and  thus  gradually  produced  other  fecondary 

VOL.  I.  G  G  g  parts 


426  GENERATION.         SECT.  XXXIX.  9.  i. 

parts  of  the  growing  fetus,  as  the  ikin,  nails,  hair,  and  the  or- 
gans which  diflinguifh  the  fexes. 

If  the  molecules  fecreted  by  the  female  organ  into  the  peri- 
carp of  flowers,  or  into  the  ovary  of  animals,  were  fuppofed  to 
confifl:  of  only  unorganized  or  inanimate  particles  ;  and  the  fi- 
brils fecreted  by  the  male  organ  only  to  poflefs  formative  appe- 
tencies to  felecl:  and  combine  with  them  ;  the  new  embryon 
mud  probably  have  always  refembled  the  father,  and  no  mules 
could  have  had  exiftence. 

But  by  the  theory  above  delivered  it  appears,  that  the  new 
offspring,  both  in  vegetable  and  animal  reproduction,  whether 
it  be  a  mule  or  not,  muft  fometimes  more  refemble  the  male 
parent,  and  fometimes  the  female  one,  and  fometimes  to  be  a 
combination  of  them  both,  as  in  the  Epigram  of  Aufonius. 

Dum  dubitat  Natura  marem,  faceretne  puellam 
Fadtus  es,  O  pulcher,  pene  puella,  Puer  ! 

IX.  i.  The  foregoing  remarks  on  vegetable  generation  are 
chiefly  tranfcribed  from  my  work  on  Phytologia,  Seel:.  VII.  and 
may  be  applied  to  animal  reproduction  •,  fince  from  this  analo- 
gy to  the  lateral  propagation  of  vegetable  buds,  if  we  fuppofe, 
that  redundant  fibrils  with  formative  appetencies  are  produced 
by,  or  detached  from,  various  parts  of  the  male  animal,  and  cir- 
culating in  his  blood,  are  fecreted  by  adapted  glands,  and  con- 
ftitute  the  feminal  fluid  ;  and  that  redundant  molecules  with 
formative  aptitudes  or  propenfities  are  produced  by,  or  detached 
from,  various  parts  of  the  female,  and  circulating  in  her  blood, 
are  fecreted  by  adapted  glands,  and  form  a  refervoir  in  the  ova- 
ry ;  and  finally  that  when  thefe  formative  fibrils,  and  forma- 
tive molecules,  become  mixed  together  in  the  uterus,  that  they 
coalefce  or  embrace  each  other,  and  form  different  parts  of  the 
new  embryon,  as  in  the  cicatricula  of  the  impregnated  egg  ;  we 
may  more  readily  comprehend  fome  circumftances,  which  are 
difficult  to  underftand  on  any  other  fyftem  of  generation. 

It  muil  be  obferved  that  this  theory  differs  from  that  of  M. 
Buffon ;  as  he  conceives  the  fame  organized  particles  to  exift 
in  the  generative  fecretions  both  of  the  male  and  female  par- 
ent j  whereas  in  this  theory  it  is  fuppofed,  that  particles  com- 
pletely organized  are  too  large  to  pafs  the  glands  of  either  fex, 
and  that  thofe,  which  are  feen  in  the  femen  by  microfcopes,  are 
the  confequence  of  the  ftagnation  of  the  fluid,  as  in  the  puftules 
of  the  itch,  and  in  the  liquid  feces  of  dyfenteric  patients.  Hence 
the  fibrils  with  formative  appetencies  and  the  molecules  with 
formative  aptitudes  or  propenfities  muft  coalefce  to  produce  the 
firft  organization. 

Secondly, 


SECT.  XXXIX.  9.  i.       GENERATION.  427 

Secondly,  in  Mr.  Buffon's  theory  the  fetus  is  fuppofed  to  be 
inftantaneoufly  produced  all  at  once  ;  whereas  in  our  theory 
there  is  believed  to  exift  a  primary,  and  fecondary  formation  ; 
that  is,  that  many  eflential  parts,  as  the  brain  and  the  heart,  are 
primarily  produced  from  the  congrefs  of  the  fibrils  with  formative 
appetencies,  and  the  molecules  with  formative  aptitudes  or  pro- 
penfities ;  and  that  thefe  combinations  acquire  new  appeten- 
cies, and  produce  or  unite  with  molecules  with  new  aptitudes, 
and  thus  generate  other  parts  of  fecondary  formation,  as  ribs, 
fingers,  inteftines,  with  the  external  form,  and  the  glands,  which 
conftitute  the  difference  of  the  fexes. 

One  great  objection  to  the  theory  delivered  in  the  former 
part  of  this  fection  on  generation  is  removed  by  this  idea  of  the 
exiftence  of  formative  fibrils,  and  formative  molecules,  which 
by  their  coalefcence  generate  various  parts  of  the  embryon  at 
the  fame  time  ;  which  is,  that  in  fome  monflrous  or  imperfect: 
fetufes  different  parts  only  are  produced,  inftead  of  the  whole  ; 
and  iuch  parts  as  would  not  appear  to  be  primary  ones.  Such 
are  the  teeth  and  hair,  which  have  been  found  in  moles  or  falfe 
conceptions,  as  they  exift  naturally  at  a  diftance  from  the  brain 
and  heart,  which  are  efteemed  to  be  the  centre  of  vitality,  and 
are  firft  vifible  in  the  embryon  chick.  Many  other  parts  in 
monflrous  births  are  faid  to  have  been  completely  formed,  where 
no  brain  nor  heart  has  exifted  ;  the  produdlion  of  which  on  oth- 
er ideas  of  generation  cannot  be  explained  ;  unlefs  it  be  fup- 
pofed, that  an  entire  embryon  had  been  at  firft  generated,  all  of 
which  had  periftied,  and  had  been  abforbed,  except  the  parts 
which  conftitute  the  monftrous  or  imperfect  fetus  at  its  birth, 
which  would  be  difficult  to  explain. 

Many  inftances  of  very  imperfect  fetufes  are  recorded  by 
Monf.  J.  J.  Sue  in  his  Rechearches  fur  la  Vitalite  ;  and  in  the 
Comment,  of  Leipfic.  I.  17.  p.  528-.  M.  Sue  differed  a  fetus 
of  five  months  old,  which  had  no  head,  nor  cheft,  nor  ftomach, 
nor  large  inteftines,  and  yet  the  inferior  half  of  the  lower  belly 
was  complete,  with  the  umbilical  cord,  male  organs  of  genera- 
tion, and  one  complete  inferior  limb,  of  which  a  print  is  given 
in  Magazin.  Encycloped.  1 797.  This  monftrous  fetus,  which 
was  only  half  of  it  formed,  fhews,  that  the  embryon  is  not  al- 
ways produced  from  one  beginning,  but  probably  from  many  . 
as  there  was  no  brain  or  heart,  the  connection  of  nerves  in  the 
lower  part  of  the  fpine  muft  have  ferved  the  purpofe  of  the 
former;  and  a  junction  of  the  large  arteries  and  veins  muft 
have  ferved  the  purpofe  of  a  heart,  producing  a  circulation  like 
that  in  the  liver,  or  in  the  aorta  and  vena  cava  of  fifb.  For  a 
previous  production  and  reabforption  of  the  other  more  effen- 

tial 


4i8  GENERATION.        SECT.  XXXIX.  9.  2. 

tial  parts  of  the  fetus,  as  the  brain  and  heart,  with  all  the  upper 
parts  of  the  body,  and  interlines,  would  feem  to  be  attended  with 
flill  greater  difficulties. 

The  miftake  of  conceiving  the  embryon  to  begin  its  forma- 
tion in  one  point  only  might  more  readily  be  fallen  into  from 
our  habitually  confidering  an  animal  as  an  individual  entity  ; 
which  it  feems  not  to  be,  till  an  union  of  the  nerves  from  every 
part  is  formed  in  the  common  fenforium,  and  produces  a  gener- 
al fenfibility,  which  is  thus  diflinguifhed  from  irritability, 
which  may  refide  in  parts  even  when  detached  from  the  fyitem, 
as  is  feen  in  the  contractions  of  the  heart  of  a  viper  taken  out 
of  the  body,  or  of  limbs  recently  cut  off, 

2.  Another  thing  difficult  to  conceive   from   thofe   theories, 
which  fuppoied  the   firft   rudiment  to  confift  of  a  fmgle  entity, 
was  to  anfwer  the  curious  queftion,  whether  the  brain,  or  heart 
and  arteries  were  firft  formed  ;  as  the  motions  of  the  arterial 
fyftem  previoufly  exerted  feem  to  have  been    necefTary  for  the 
fecretion  of  fenforial  power    in  the  brain,    and  converfely  thofe 
motions  of    the    arterial    fyftem    feem   previoufly  to    require 
the  fenforial  power  derived  from  the  brain. 

This  difficulty  vanifhes,  when  we  believe,  that  many  parts  of 
the  young  embryon  can  be  begun  at  the  fame  time,  as  various 
formative  fibrils  and  formative  molecules  coalefce,  as  they  come 
into  contact,  with  each  other ;  and  thus  the  rudiments  of  the  brain 
and  of  the  heart  may  be  fabricated  at  the  fame  inftant  of  time. 

3.  If  fibrils  with  formative  appetencies,  and  molecules  with 
formative  aptitudes  or  propenfities  exifl  in  the  circulation  both 
of  males  and  females,  why  do  they  not   coalefce  there  ?    This 
feems  an  unanfwerable  objection  to   M.  BufFon's  theory,  who 
holds,  that  organic  particles  exifl  in  the  circulation  ;  but  in  the 
fyftem  above  delivered,  no  organic  particles  exifl  in  the  blood  in 
their  combined  ftate  ;   and  hence  no  microfcopic  animalcula  are 
feen  in  blood  recently  drawn,  though  they  may  appear  after  fome 
hours  flagnation  ;  but  the  formative  fibrils  only  and  formative 
molecules  are  believed  to  exift  in  the  circulation ;  and  that  they 
do  not  produce  combinations  there,  as  they  cannot  reft  ;   and  as 
fuch  combinations  would  be  too  large  to  pafs  the  capillary  vef- 
fels  of  the  aorta,  and  of   the  pulmonary  artery,   and  of  all   the 
glands,  and  muft  there  be  perpetually  diflevered,  if  they  could 
be  previoufly  formed  in  the  larger  veflels. 

4.  If  fimilar  organized  particles  were  fecretcd  by   the  fexual 
glands  of  the  male  and  alfoof  the  female,  why  do  they  not  pro- 
duce parts,  or  rudiments,  of  an  embryon  in  the  male  or  female 
yefervoirs  without  a  reciprocal  commixture.       This  is  another 
Unanfwerable  objection  to  M.  BufFon's  theory,   but  not  to  that 

above 


SECT.  XXXIX.  9.  5.          GENERATION.  429 

above  delivered  ;  which  latter  fuppofes,  that  no  organized  par- 
ticles are  fecreted  either  by  the  glands  of  the  male  or  female ; 
but  that  the  fibrils  with  formative  appetencies  are  fecrered  by 
the  glands  of  the  male,  and  the  molecules  with  formative  apti- 
tudes or  propenfities  are  fecreted  by  thofe  of  the  female  5  and 
that,  when  thefe  combine,  the  organization  commences. 

5.  If  the  whole  of  the  embryon  is  fuppofed  to  be  fynchron- 
ouily  produced,  which  is  faid  almoft  to  be  viiible  in  the  cicatric- 
ula  of  the  egg  even  before  incubation,  how  can  this  happen 
from  a  commixture  of  any  kind  of  particles  deduced  from  both 
the  male  and  female  parents,  if  thofe  particles  are  previoufly  dr- 
tached  from  the  various  parts  of  their  refpe£Hve  bodies  ;  fmce 
no  parts  fimilar  to  the  female  organs  can  previoufly  exift  in  the 
male,  nor  any  of  thofe  of  the  male  organs  previoufly  exift  in  the 
female  ?  This  fynchronous  production  of  all  the  parts  of  the  em- 
bryon  is  fuppofed  by  M.  BufTbn,  and  militates  againft  his  the- 
ory ;  and  if  it  was  true,  would  equally  militate  againft  that 
above  delivered  ;  but  from  all  the  hittories  of  the  beginning  and 
growing  fetus  given  by  anatomifts  there  are  parts  of  fecondary 
formation,  as  well  as  parts  of  primary  formation  ;  thus  the  head 
and  fpine  of  the  back  are  firft  feen  both  in  the  oviparous  and  vi- 
viparous embryon,  and  afterwards  the  lungs,  ribs,  limbs,  nails, 
hairs,  and  feathers,  and  laft  of  all  perhaps  the  glands  which  dif- 
tinguifh  the  fexes ;  as  thefe  are  the  laft,  which  afterwards  ar- 
rive at  their  maturity. 

This  fecondary  formation  of  parts  is  evinced  in  the  long  cau- 
dexes  of  the  buds  of  trees,  which  form  a  filament  of  the  bark  ; 
as  from  any  part  of  this  a  new  plumula  or  leaf,  which  is  the 
lungs  of  the  embryon  bud,  can  be  produced,  when  the  upper 
part  of  a  branch  is  lopped  off,  as  fhewn  in  No  9,  4.  of  this 
iedlion  ;  and  is  further  evinced  in  fome  animals,  as  when  a 
common  earth-worm  is  cut  in  halves,  the  tail-part  can  produce 
a  head- part,  and  the  head-part  can  produce  a  tail-part  ;  and 
laftly,  it  is  evinced  from  the  power,  which  crabs  poileis  of  gen- 
erating a  new  leg,  when  one  of  them  is  accidentally  broken  off. 
This  power  is  like  wife  poflefled  by  the  human  body,  as  in  the 
production  of  new  teeth,  and  then  of  a  fecond  fet,  and  there  are 
ibme  inftances  on  record,  that  a  third  fet  of  teeth  have  been  fab- 
ricated in  the  jaw-bones  of  age. 

The  power  of  formation  of  fecondary  parts  in  the  human  fyf- 
tem  is  wonderfully  (hewn  by  the  following  cafe,  which  is  related 
by  Mr.  White  in  the  Mancliefter  Memoirs,  Vol.  I.  p.  338. 
"  Some  years  ago  I  delivered  a  lady  of  rank  of  a  line  boy,  who 
had  two  thumbs  on  one  hand,  or  rather  one  thumb  double  from 
the  iirlt  joint,  the  outer  one  being  rather  lefs  than  the  inner, 

and 


430  GENERATION.        SECT.  XXXIX.  10.  i. 

nnd  each  of  them  having  a  perfect  nail.  When  he  was  about 
three  years  old,  I  was  defired  to  take  of  the  lefler  one  ;  which  I 
did,  but  to  my  great  aftonifliment  it  grew  again,  and  along  with 
it  the  nail.  The  family  afterwards  went  to  refide  in  London, 
when  the  father  (hewed  it  to  Mr.  Bromfield  ;  who  faid,  that  he 
fuppofed  Mr.  White,  from  fear  of  damaging  the  joint  had  not 
taken  it  wholly  out,  but  that  he  would  diflefl:  it  out  entirely, 
and  that  then  it  would  not  return.  He  accordingly  executed 
his  plan,  and  turned  the  ball  out  of  the  focket.  Notwithftand- 
ing  this  it  grew  again,  a  frefli  nail  was  formed,  and  the  thumb 
remains  in  this  ftate." 

Recapitulation. 

X.  On  confidering  the  production  of  vegetable  buds  and 
feeds,  of  fome  infeds,  and  of  more  perfect  animals,  the  modes 
of  generation  may  be  divided  into  folitary  and  fexual. 

i.  The  fir  ft  con  fifts  either  in  folitary  lateral  generation,  as 
in  the  reproduction  of  the  buds  or  bulbs  of  vegetables,  and  of  the 
young  of  the  polypus,  and  of  the  hydra  (tentorea,  or  of  the  foli- 
tary internal  generation,  as  of  the  aphis,  vine-fretter,  a£Hnia, 
fea-anemone,  tenia,  tape-warm,  and  the  volvox  ;  all  which  are 
properly  a  viviparous  progeny,  as  they  are  not  preceded  by  feeds, 
or  fpawn,  or  eggs. 

In  thefe  modes  of  reprodu&ion  I  fuppofe,  that  fibrils  with 
formative  appetencies,  and  molecules  with  formative  aptitudes 
or  propenfities,  produced  by,  or  detached  from,  various  eflentiai 
parts  of  their  refpe&ive  fyftems,  float  in  the  vegetable  or  infecl 
blood.  Thefe  may  be  termed  animalized  particles  of  primary 
combination,  confifting  of  a  folid  particle  adjoined  to  a  peculiar 
appetency  or  propenfity ;  which  latter  may  be  efteemed  its  ethe- 
real part,  as  magnetifm  or  electricity  may  be  added  to  iron  or  to 
other  inanimate  bodies. 

Thefe  fibrils  with  formative  appetencies,  and  molecules  with 
formative  aptitudes  or  propenfities,  cannot  unite,  or  continue 
united,  in  the  circulating  blood,  as  they  are  not  at  reft  ;  and 
would  be  too  large  to  pafs  the  capillaries  of  the  aorta,  pulmo- 
nary artery,  and  glands,  if  they  could  be  united  in  the  larger 
veflels ;  they  are  therefore  felected  or  fecreted  feparately  by 
adapted  glands,  and  when  mixed  together  combine,  and  form 
the  primary  parts  of  the  new  organization  of  an  embryon. 

Thofe  fecreted  from  the  long  caudex  of  vegetable  buds  are 
depofited  beneath  the  cuticle  of  the  bark  of  trees,  and  there 
uniting  form  a  new  caudex  gemmx  along  the  fide  of  the  parent 
one  ;  which  has  the  property  of  producing  fecondary  organiza- 
tions 


SECT.  XXXIX.  10. 2.         GENERATION.  431 

tionsfrom  the  new  powers  it  has  acquired,  fo  as  to  form  a  leaf 
or  lungs  either  at  its  fummit  in  the  axilla  of  the  parent  leaf,  or  in 
any  other  part  of  its  length  ;  and  alfo  to  form  radicles  below, 
or  from  any  amputated  part. 

This  new  caudex  gemmae  is  proved  to  commence  its  forma- 
tion in  feveral  places  at  the  fame  time  from  the  triple  caudex  of 
the  bud  of  a  tree,  which  has  been  twice  fucceflively  ingrafted, 
which  we  have  called  a  triple  mule;  but  as  the  new  vegetable 
confifts  in  general  of  a  combination  of  parts  derived  from  one 
parent,  it  much  more  accurately  refembles  that  parent  in  its 
form,  growth,  and  difeafes,  than  the  progeny  from  fexual  or 
feminal  generation.  The  fame  circumftances  occur  to  the  vege- 
tables, which  poffcfs  (hort  and  flat  caudexes,  which  exiit  be- 
tween the  radicles  and  the  root-leaves,  as  in  the  bulbs  of  tulips 
and  onions ;  which  might  poilibly  be  ingrafted  on  each  other  likv; 
the  buds  of  different  trees,  and  form  curious  mule  bulbs. 

This  lateral  or  folitary  mode  of  propagation  belongs  likewife 
to  the  polypus  of  our  ditches,  and  to  the  hydra  ftentorea,  and 
probably  to  many  other  infects. 

2.  There  is  alfo  a  folitary  internal  mode  of  generation,  which 
occurs  in  the  viviparous  productions  of  the  aphis,  which  are 
known  to  proceed  for  eight  or  nine  fucceflive  generations  with- 
out the  congrefs  of  fexes  ;  but  what  is  extraordinary,  a  con- 
grefs  of  fexes  appears  to  be  neceffary  in  their  production  of  an 
oviparous  progeny  in  the  autumn  for  the  prefervation  of  the  fpe- 
cies  during  winter  ;  whence  it  would  feem,  that  folitary  genera- 
tion always  produces  a  viviparous  offspring.  For  the  more  par- 
ticular hillory  of  this  wonderful  and  important  infect  fee  Phyt- 
ologia,  Seel.  IX.  and  XIV.  To  which  may  be  added,  that  a 
fimilar  internal  folitary  mode  of  reproduction  probably  obtains 
in  the  tenia,  or  tape- worm,  of  the  intellines,  which  afflicts  va- 
riety of  animals,  and  of  the  aftinea,  or  fea-anemone,  and  of  the 
volvox,  as  defcribed  in  the  Syftema  Nature  of  Linnseus. 

The  effential  difference  between  the  folitary  lateral  generation 
and  the  folitary  internal  generation  feems  to  confiit  in  this  ; 
that  in  the  former  there  are  many  glands,  which  fecrete  or  pro- 
duce the  fibrils  with  formative  appetencies  ;  and  many  other 
glands,  which  fecrete  or  produce  the  molecules  with  formative 
aptitudes  or  propenfities  ;  and  that  thefe  numerous  fecretioris  are 
mixed  together  and  combine  in  one  large  receptacle  beneath  the 
cuticle  of  trees,  and  of  fome  infects,  and  there  combining  gener- 
ate the  organized  particles,  which  conflitute  the  rudiment  of 
the  new  embryon,  producing  many  of  the  effential  parts  of  it  at 
the  fame  time  ;  whereas  in  the  latter,  there  probably  exifts  bur 
one  fet  of  glands,  which  fecrete  the  fibrils  with  formative  appe- 
tencies ; 


432  GENERATION.        SECT.  XXXIX.  10.  3. 

tencies  ;  and  another  fet  of  glands  which  fecrete  the  molecules 
with  formative  propenfities  ;  and  that  thefe  primary  particles 
are  received  and  mingled  together  in  a  lefs  extenfive  refervoir  ; 
as  an  univerfal  exiftence  of  procreative  glands,  as  in  the  long 
caudexes  of  vegetable  buds,  might  have  been  inconvenient  to 
locomotive  animals.  Thefe  therefore  feem  to  conftitute  a  link 
of  the  chain  of  nature  between  the  lateral  production  of  buds, 
and  the  fexual  hermaphrodites,  which  are  next  to  be  confidered. 

3.  The  fexual  mode  of  propagation  may  be  divided  firft  into 
hermaphrodite  or  reciprocal  fexual  generation,  as  in  the  flowers 
of  moft  vegetables,  and  in  fome  large  infects,  as  in  dew-worms 
and  {hell  fnails,  and  probably  in  many  fmailer  ones.  Secondly 
into  the  fimpler  fexual  generation,  which  occurs  in  the  larger 
animals. 

The  fexual  modes  of  generation  may  alfo  be  divided  into  the 
feminal  or  oviparous  modes,  as  the  feeds  of  plants,  the  fpawn 
of  fifh,  and  of  infects,  and  the  eggs  of  birds  ;  and  fecondly  into 
the  viviparous  modes,  as  the  fummit- bulbs  of  fome  vegetables, 
as  of  polygonum  viviparum,  magical  onions,  and  the  cloves  of 
garlic  ;  as  thefe  fummit-bulbs  fucceed  the  fexual  congrefs  of  the 
male  and  female  organs  of  flowers  ;  and  are  not  buds,  as  their 
roots  or  caudexes  do  not  pafs  down  the  ftem  of  the  plant  into 
the  ground  ;  and  are  therefore  a  fexual  viviparous  progeny  of 
vegetables :  but  the  principal  viviparous  fexual  productions  are 
thofe  of  quadrupeds  and  of  mankind. 

Next  to  the  internal  folitary  mode  of  propagation  nature  feems 
to  have  produced  the  hermaphrodite  fyltem  of  reproduction,  as 
in  molt  flowers  ;  and  in  fnails  and  dew-worms  ;  in  thefe  the 
mafculine  and  feminine  organs  are  generally  external  and  totally 
feparated  from  each  other,  and  confill  of  glands,  which  fecrete 
the  fibrils  with  formative  appetencies,  and  the  molecules  with 
formative  propenfities  from  the  fame  mafs  of  biood. 

Hence  in  vegetable  productions  the  trees  from  feed,  as  apple 
trees,  fometimes  exactly  refemble  the  parent  tree,  like  the  buds 
and  bulbs,  which  are  produced  without  fexual  intercourfe  ;  at 
other  times  they  do  not  exactly  refemble  the  parent  tree,  which 
feems  to  be  owing  to  the  anther-dud  fometimes  of  the  fame 
flower,  or  fometimes  of  other  flowers  in  its  vicinity,  caufing  the 
impregnation  of  the  Itigma,  But  in  hermaphrodite  infects,  as 
the  (hell-fnail,  and  dew-worm,  I  have  frequently  obferved,  that 
they  impregnate  each  other  reciprocally,  though  it  is  attended 
with  much  danger  and  inconvenience  to  them  ;  and  I  thence 
conclude,  that  they  have  not  the  power  to  impregnate  them- 
felves  by  the  conjunction  of  their  own  organs  of  reproduction, 
fmce  if  that  had  happened,  the  progeny  would  probably,  like  the 

buds 


SECT.  XXXIX.  i0. 4-        GENERATION,  433 

buds  of  trees,  more  exactly  have  refembled  the  parent  ;  and  no 
improvement  of  the  fpecies,  or  no  new  fpecies  from  the  fame 
genus,  could  have  been  procreated  •,  which  latter  circumftance 
has  probably  much  increafed  the  number  both  of  animal  and 
vegetable  productions. 

4.  Laftly,  the  fimple  mode  of  fexual  generation  differs  from 
the  reciprocal  or  hermaphrodite  mode  of  generation  ;  as  the 
glands,  which  conftitute  the  mafculine  and  feminine  organs,  fe- 
crete  the  fibrils  with  formative  appetencies  and  the  molecules 
with  formative  propenfities  from  different  mafTes  of  blood  ;  as  a 
double  fyftem  of  organs  might  have  been  cumberfome,  if  they 
had  exifted  together  in  larger  and  more  active  animals  :  though 
it  is  not  improbable,  that  all  animals  were  originally  hermaphro- 
dite, according  to  the  opinion  of  Plato  in  refpect  to  human  kind, 
as  would  appear  from  the  teats  or  nipples,  as  well  as  the  pecto- 
ral glands,  which  are  (till  to  be  feen  in  men  and  in  all  male 
quadrupeds. 

In  this  mode  of  propagation  the  fibrils  with  formative  appe- 
tencies detached  from  fome  or  many  eflential  parts  of  the  male 
parent,  or  which  were  formed  from  the  blood  accordant  to  thofe 
eflential  parts,  are  fecreted  by  the  male  organ  into  an  adapted 
reiervoir  •,  and  the  molecules  with  formative  propenfiries  detach- 
ed from  fome  or  many  efil'ntial  parts  of  the  female  parent, 
or  which  are  formed  from  the  blood  accordant  to  thofe  eflen- 
tial  parts,  are  fecreted  by  the  female  organ  into  an  adapted  ref- 
ervoir  :  and  in  this  circumftance  fecretion  differs  from  nutri- 
tion •,  in  the  latter  certain  particles  of  the  blood,  which  were 
not  previoufly  ufed  in  the  fyftem,  are  embraced  and  become  a 
folid  part  of  the  animal  ;  in  the  former  certain  particles,  which 
had  previoufly  been  ufed  in  the  fyttem,  and  detached  from  it, 
are  imbibed  by  adapted  glands,  and  depofited  in  refervoirs,  or 
detruded.  See  Sett.  XXXVII.  3 

Finally  when  thefe  are  mixed  together  in  the  act  of  copula- 
tion, i hey  embrace  and  coalefce,  and  form  the  eflential  parts  of 
the  new  embryon  ;  the  production  of  which  commences  in 
more  places  than  one  ;  as  the  brain  and  heart,  with  fome 
nerves,  arteries,  veins,  and  abforbent  vefTds,  are  probably  form- 
ed at  the  fame  time,  and  almoft  inftantaneoufly. 

Thtfe  new  fibrous  combinations  acquire  new  appetencies, 
and  produce  molecules  by  their  vital  activity  with  new  aptitudes 
or  propenfities  }  and  thus  gradually  fabricate  other  feccndary 
parts  either  fynchronous  or  fucceflive  ones,  as  the  ribs,  lungs, 
limbs,  and  finally  the  organs,  which  diftinguiih  the  fexes,  with 
the  general  difference  of  the  male  and  female  form  throughout 
the  whole  fyftem,  according  to  the  prevailing  or  preponderant 

VOL.  I.  Huh  aftiviry 

. 


434  GENERATION.        SECT.  XXXIX.  16. 5. 

activity  or  quantity  of  the  fibrils  with  appetencies  derived  from 
the  male,  or  the  molecules  with  propenfities  derived  from  the 
female.  This  idea  differs  from  the  theory  of  M.  Buffon,  which 
fuppofes  the  whole  embryon  to  be  formed  at  the  fame  time,  or 
that  the  fexual  organs  are  firft  produced,  as  a  centre  of  animali- 
zation  ;  but  the  fecondary  produftion  of  thefe  organs  is  agreea- 
ble to  all  obfervations  on  the  growing  chick  or  fetus,  and  is 
ftrongly  countenanced  by  the  flow  progrefs  of  thefe  parts  after 
birth,  which  are  not  complete  till  the  maturity  of  the  animal, 
which  is  termed  its  puberty. 

The  power,  which  the  primary  or  eiTential  parts  of  the  em- 
bryon poffefs,  of  producing  fecondary  or  lefs  effential  parts,  is 
analogous  to  the  production  of  a  new  plumula  or  new  radicles 
by  the  vegetable  embryon,  or  caudex  gemmx  mentioned  in  No. 
8.  4  of  this  fection  ;  and  to  the  power  with  which  crabs  are 
furnifhed  to  produce  a  new  limb,  when  one  is  broken  off;  and 
to  that  of  earth-worms,  which  when  cut  in  halves,  can  acquire 
a  new  head  or  a  new  tail  ;  and  to  the  power  in  a  human  infant 
of  regenerating  a  fupernumerary  thumb,  to  the  production  of 
a  new  fet  of  teeth,  and  the  developement  of  the  fexual  glands 
at  puberty.  See  No,  9.  5.  of  this  feet  ion. 

5.  Some  of  thefe  fexual  reproductions  confift  of  feeds,  or 
eggs,  in  which  the  eflential  parts  of  the  vegetable  or  of  the  chick 
are  already  formed,  as  may  be  feen  in  the  corculum  of  many 
feeds,  and  in  the  cicatricula  of  an  egg,  as  foon  as  it  leaves  the 
body  of  the  hen  before  incubation  In  this  (late  the  embryon 
does  not  continue  to  grow,  if  expofed  only  to  the  ufual  degree 
of  the  warmth  and  moifture  of  the  atmofphere,  but  may  be  long 
kept  in  its  itate  of  infenfible  life  •,  though  it  will  foon  ferment 
or  putrefy,  if  it  be  deprived  of  life. 

Other  wife  thefe  fexual  productions  confift  of  fpawn,  which 
differs  from  eggs  by  the  embryon  not  being  included  in  a  hard 
unyielding  fhell  ;  fo  that  the  receptacle  diftends,  as  the  fetus 
increafes  in  fize  ;  which  is  feen  in  the  fpawn  of  fifti  and  frogs, 
and  in  the  eggs  of  fpiders,  fnails,and  many  other  infects.  From 
this  diftenfibility  of  the  bag,  which  contains  the  embryons  of 
fifh  and  infects,  it  feems  more  to  refemble  the  uterus  of  quad- 
rupeds than  the  eggs  of  birds  ;  as  in  the  former  the  receptacle 
increafes  in  fize  along  with  the  fetus,  and  fupplies  the  liquor  of 
the  amnios,  as  it  is  wanted  ;  but  differs  by  its  not  continuing  in 
the  matrix  of  the  mother,  till  the  exclufion  of  the  young  animal 
into  the  cold  and  dry  atmofphere. 

XL  i.  Finally  we  conclude,  that  as  the  inanimate  particles 
or  atoms  of  matter  unite  into  cryftals  of  various  forms  by  the 
various  powers  of  attraction,  which  fome  kinds  of  them  poffefs  ; 

and 


SECT.  XXXIX.  ii.  i.        GENERATION.  435 

and  the  various  aptitudes  to  be  attracted,  which  other  kinds 
poflefs  ;  which  may  be  termed  the  ethereal  properties  of  inani- 
mate matter  ;  fo  the  animated  fibrils  or  molecules,  which  poflefs 
appetencies  to  embrace,  and  propenfnies  to  be  embraced,  which 
may  be  called  their  etherial  properties,  coalefce,  when  they  ap- 
proach each  other,  and  form  organized  bodies. 

When  this  organization  begins  only  in  a  fingle  point,  and 
only  enlarges,  as  it  acquires  new  kinds  of  appetencies,  as  ex- 
plained in  the  former  part  of  this  feftion  on  Generation,  I  fup- 
pofe  an  animated  being  commences  5  fuch  as  the  animalcula, 
which  are  feen  by  the  folar  microfcope  in  variety  of  fluids, 
which  have  for  a  time  itagnated  ;  as  in  infufions  of  the  feeds  of 
plants  ;  in  the  femen  of  animals,  and  of  all  other  vegetable  and 
animal  recrements  difFufed  in  water.  Thefe  microfcopic  ani- 
mals I  fuppofe  are  produced  by  the  ftagnation  of  the  femen  in 
the  veficulae  feminales,  and  by  the  matter  of  the  itch  by  ftagna- 
tion in  its  puftules,  and  by  the  feces  by  their  ftagnation  in  the 
inteftines  ;  but  I  believe,  that  they  do  not  exift  in  the  blood,  nor 
in  fluids  recently  fecreted.  Thefe  microfcopic  animals  confti- 
tute  the  primordium  vitss,  or  firft  order  of  animal  life,  and  prob- 
ably are  not  originally  propagated,  but  fimply  arife  from  the  dif- 
folution  of  all  vegetable  or  animal  matter. 

This  fpontaneous  production  of  microfcopic  animals  appears 
from  their  being  difcovered  in  a  few  days  in  all  folutions  ofde- 
compofing  vegetable  and  animal  matters,  as  well  after  having 
been  fubje£ted  to  the  heat  of  boiling  water  as  before.  Thus 
Mr.  Reaumur  put  fome  boiling  veal  broth,  and  Mr.  Baker  put 
fome  boiling  hot  mafhed  potatoes  into  hot  phials,  which  were 
clofed  with  glafs-ftopples  ;  and  both  of  them  in  three  days  be- 
came as  full  of  animalcula,  as  the  fame  materials  put  into  other 
phials  without  being  previoufly  boiled.  Bakeron  the  Microfcope. 

It  is  probable  that  there  exift  microfcopic  vegetable  produc- 
tions, as  well  as  microfcopic  animals,  which  may  not  have  been 
attended  to,  owing  to  the  quick  evaporation  of  a  drop  of  water 
in  a  microfcope  ;  and  that  thefe  are  firft  formed  fpontaneoufly 
from  the  decompofing  recrements  of  vegetable  or  animal  bodies  j 
and  that  they  afterwards  generate  others  rather  more  per  feel: 
than  themfelves  by  lateral  reprodu£Hon.  From  this  kind  of 
fpontaneous  microfcopic  vegetation,  I  fuppofe  the  green  matter 
obferved  by  Dr.  Prieftly,  which  gives  up  fo  much  vital  air  in 
the  funfhine,  originates  ;  and  that  it  afterwards  generates  a  fuc- 
ceeding  progeny.  As  it  is  at  firft  (lowly  produced  in  water  in 
any  fituation,  and  afterwards  is  propagated  with  great  rapidity  ; 
and  according  to  the  obfervations  of  Senebier  it  is  mod  quickly 
produced  in  water  in  which  vegetable  or  animal  fubftances  are 

in 


436  GENERATION.        SECT.  XXXIX.  i  i.z. 

in  a  ftate  of  diffblution.  Whence  fome  philofophers  have  late- 
ly fuppofed  this  green  matter  to  be  of  animal  origin,  as  it  chang- 
es from  a  globular  form  to  that  of  a  thread  •,  which  has  occa- 
Coned  much  inveftigation  by  Fontana,  Ingenhouz,  and  Sene- 
bier.  Journal  de  Phyfique  par  Delametherie,  T.  5. 

In  the  fame  manner  the  mucor,  or  mould,  which  grows  on 
all  decompofing  vegetable  and  animal  fubftances,  which  are  at 
reft  in  a  proper  degree  of  moifture  and  warmth,  and  which 
thence  appears  to  have  no  parent,  is  probably  firft  produced  by 
the  fpontaneous  appetencies  and  aptitudes  or  propenfities  of  the 
decompofed  particles  of  organic  bodies  j  and  probably  thefe 
new  combinations  are  at  firft  microfcopic  objects,  which  pro- 
duce others  by  lateral  or  folitary  generation,  more  and  more 
perfect  and  of  greater  magnitude  than  themfelves,  but  which 
never  acquire  the  organization  neceffary  for  fexual  reproduc- 
tion. The  fungi  which  grow  only  on  decaying  parts  of  trees 
or  other  vegetables,  as  well  as  the  muChrooms  from  horfe  dung, 
which  commence  with  fmall  hair-like  roots,  and  probably  never 
produce  feeds,  feem  to  arife  in  a  fimilar  manner  from  fpontane- 
ous microfcopic  organization,  improved  and  magnified  by  fuc- 
ceflive  folitary  generations. 

2.  The  fecond  kind  of  animal  production,  which  is  properly 
generation,  commences  in  more  points  than  one ;  as  in  the  pro- 
duction of  the  long  caudexes  of  the  buds  of  trees  ;    and  the  ani- 
mated fibrils  and  molecules  firft  combine,    and  form  organized 
bodies  ;  and  thefe  unite  again,  where  they  are  in  contact  ;  and 
thus  the  new  embryon  commences  in   many  points  at  once  ; 
and  the  folitary  mode  of  generation  is  fecondary  to  the  produc- 
tion of  the  fmalleft  microfcopic  animals,  which  I  fuppofe  com- 
mence their  exiftence  in  one  point  only,  that  is,  by  the  produc- 
tion firft  of  a  fingle  living  filament,  which  I  formerly  believed 
to  be  the  general  mode  of  propagation.     This  folitary  mode  of 
generation  occurs  in  the  production  of  the  buds  of  all  vegeta- 
bles ;  and  perhaps  the  moft  imperfect  vegetables,  as  truffles,  and 
other  fungi,  are  only  propagated  by  buds  to  this  day,   not  hav- 
ing yet  acquired  fexual  organs,   as  feems  alfo  to  occur  in  fome 
imperfect  animals,  as  the  polypi,  hydra,  and  tenia. 

3.  Other  vegetables  have  acquired   an  hermaphrodite  ftate, 
^nd  poflefs  external  fexual  organs,  as  in  moft  flowers  ;   but  both 
the  male  and   female  organs  acquire  or  produce  their  adapted 
fluids  from  the  fame  mafs  of  blood,  and  thus  refemble  hermaph- 
rodite infects,  as  fnails  and  worms. 

4.  Other  vegetables  have  acquired  a  Reparation  of  the  fexes, 
cither  on  the  fame  plant,  as  in  the  clafs  of  vegetables  termed  by 
Linnaeus,  monoecia,  or  on  different  plants,  as  in  the  clafs  dioe- 

gia; 


SECT.  XXXIX.  n.  5.  GENERATION.  437 

cia  ;  the  buds  of  which  may  properly  be  called  male  or  female 
vegetables,  and  differ  in  iome  degree  in  their  form  and  colour, 
like  male  and  female  animals  ;  and  in  this  they  refemble  the 
larger  animals,  as  their  fexual  glands,  acquire  or  produce  their 
prolific  fluids  from  different  maiies  of  blood  ;  which  is  probably 
lefs  cumberfome  to  the  individual,  than  where  both  the  fexual 
glands  exift  in  one  organized  fyftem. 

In  all  thefe  vegetable  and  animal  modes  of  reproduction,  I 
fuppofe  the  new  embryon  to  begin  in  many  points,  and  in  com- 
plicated animals  in  many  more  points  probably  than  in  the  more 
fimple  ones  ;  and  finally,  that  as  thefe  new  organized  parts,  or 
rudiments  of  the  embryon,  acquire  new  appetencies,  and  pro- 
duce or  find  molecules  with  new  propenfities,  many  fecondary 
parts  are  afterwards  fabricated. 

Thus  it  would  appear,  that  all  nature  exifts  in  a  ftate  of  per- 
petual improvement  by  laws  imprefled  on  the  atoms  of  matter 
by  the  great  CAUSE  OF  CAUSES  ;  and  that  the  world  may  flill  be 
in  its  infancy,  and  continue  to  improve  FOR  EVER  AND  EVER. 

5.  Concerning  the  fpontaneous  production  of  microfcopic 
animalcules,  I  beg  leave  to  repeat,  firft,  that  I  fuppofe  the 
fmalleft  ones  to  be  formed  by  the  coalefcence  or  embrace  of  the 
animal  fibrils,  which  poflefs  appetencies,  with  the  animal  mole- 
cules, which  poflefs  correfpondent  propenfities  ;  and  that  the 
animal  fibrils  and  molecules  are  found  in  all  vegetable  and  ani- 
mal matter,  as  its  organization  becomes  decompofed  ;  if  there 
exifts  along  with  it  fufficient  moifture  and  proper  warmth. 

Secondly,  that  this  kind  of  fpontaneous  reproduction  refem- 
bles  a£lual  generation  in  its  confuting  of  the  coalefcence  of  an- 
imal fibrils  with  appetencies  and  animal  molecules  with  corref- 
pondent propenfities,  that  in  the  former  they  meet  each  other 
in  the  folution  of  animal  matter,  as  it  decornpofes  by  dagna»- 
tion  ;  whereas  in  the  latter  thefe  formative  fibrils  and  molecules 
are  fecreted  by  different  glands  from  the  blood  of  the  parent. 

Thirdly,  that  the  firft  animalcules  produce  other  ones  by  ac- 
tual generation,  but  without  fexes,  like  the  buds  of  trees,  and 
that  as  many  generations  may  occur  in  a  day,  perhaps  in  an 
hour,  I  conceive,  that  they  may  gradually  acquire  new  organi- 
zations, and  improve  by  addition  of  new  parts,  as  of  fins,  mouth, 
inteftines,  and  finally,  perhaps,  fexual  organs  of  reproduction, 
Thus  the  feed  of  a  tulip  produces  a  fmall  root  the  fize  of  a  pea 
the  firft  fummer,  with  a  fummit  like  a  blade  of  grais ;  this  dies 
in  autumn,  having  previoufly  produced  a  fuccefTor  larger  than 
itfelf,  and  with  a  ftronger  leaf  or  fummit  ;  in  the  autumn  this 
likewife  perifhes,  and  a  third  generation  is  produced,  which  is 
Itill  larger  and  more  perfect  *  till  the  fifth  generation  from  the 

feed 


438  GENERATION.         SECT.  XXXIX.  12.  r. 

feed  becomes  fo  much  more  perfect  as  to  produce  fexual  organs 
of  reproduction,  as  the  flower  with  its  anthers  and  (ligma. 

This  curious  analogy  is  not  only  fupported  by  the  feedling 
buds  of  trees,  which  fucceed  each  other  for  ten  or  twelve  gen- 
erations, the  parent  buds  dying  in  the  autumn,  before  they  be- 
come fafficiently  perfect  to  form  the  fexual  organs  of  reproduc- 
tion in  their  flower,  as  occurs  in  apple-trees  ;  but  is  alfo  ob- 
fervable  in  a  complete  infect,  as  in  the  aphis,  which  continues 
•  to  propagate  for  nine  generations  from  the  egg  without  fex  ; 
and  then  becomes  fo  perfect  as  to  form  fexual  organs,  and  to 
produce  an  oviparous  progeny.  Other  infects,  as  the  moths 
and  butterflies,  undergo  a  great  change  of  form,  before  they 
acquire  the  property  of  fexual  reproduction  ;  and  probably  in- 
numerable other  kinds  of  infects  are  fubject  to  the  fame  law. 

This  idea  of  the  production  and  changes  of  form  of  microf- 
copic  animalcules  is  countenanced  by  the  fmaller  kinds,  never, 
I  believe,  having  been  feen  in  their  egg  or  infant  itate  ;  and  by 
fome  of  them  being  capable  of  being  revived  in  a  few  hours  by 
warmth  and  moifture  after  having  been  dry  and  motionlefs  for 
months,  as  the  infect  named  vorticella.  And  laftly,  from  the 
changeful  forms,  which  fome  of  them  affume,  as  that  which  is 
called  proteus.  See  Baker  and  Adams  on  the  Microfcope. 

Thus  as  by  the  attractions,  and  aptitudes  to  be  attracted,  which 
exift  in  inanimate  matter,  various  new  bodies  are  produced  from 
the  decompofition  of  thofe,  which  previoufly  exifted  ;  fo  by  the 
appetencies  to  embrace,  and  the  propenfities  to  be  embraced,  in 
animalized  matter,  various  new  animalcules  are  formed  from 
the  decompofition  of  thofe,  which  previoufly  exifted  ;  owing  in 
both  cafes  to  the  immutable  laws  imprefled  both  on  inanimate 
and  on  organized  matter  by  the  great  FIRST  CAUSE. 

XII.  i .  CAUSE  AND  EFFECT  may  be  confidered  as  the  progref- 
fion,  or  fucceflive  motions,  of  the  parts  of  the  great  fyftem  of 
Nature.  The  ilate  of  things  at  this  moment  is  the  effect  of  the 
ilate  of  things,  which  exifted  in  the  preceding  moment  ;  and 
the  caufe  of  the  ftate  of  things,  which  (hall  exift  in  the  next 
moment. 

Thefe  caufes  and  effects  may  be  more  eafily  comprehended, 
if  motion  be  confidered  as  a  change  of  the  figure  of  a  group  of 
bodies,  as  propofed  in  Sect.  XIV.  2.  2.  inafmuch  as  our  ideas 
of  vifible  or  tangible  objects  are  more  diftinct,  than  our  ab- 
ftradted  ideas  of  their  motions.  Now  the  change  of  the  con- 
figuration of  the  fyftem  of  nature  at  this  moment  muft  be  an 
effect  of  the  preceding  configuration,  for  a  change  of  configur- 
ation cannot  exift  without  a  previous  configuration  ;  and  the 
proximate  caufe  of  every  effect  muft  immediately  precede  that 

effect. 


SECT.  XXXIX.  12.  2.        GENERATION. 

effect.  For  example  a  moving  ivory  ball  could  not  proceed 
onwards,  unlefs  it  had  previoufly  begun  to  proceed ;  or  unlefs  an 
impulfe  had  been  previoufly  given  it ;  which  previous  motion  or 
impulfe  conftitutes  a  part  of  the  lad  fituation  of  things. 

As  the  effects  produced  in  this  moment  of  time  become 
eaufes  in  the  next,  we  may  confider  the  progreffive  motions  of 
objects  as  a  chain  of  eaufes  only  ;  whofe  firft  link  proceeded 
from  the  great  Creator,  and  which  have  exifted  from  the  begin- 
ning of  the  created  univerfe,  and  are  perpetually  proceeding. 

2.  Thefe  eaufes  may  be  conveniently  divided  into  two  kinds, 
efficient  and  inert  eaufes,  according  with  the  two  kinds  of  enti- 
ty fuppofed  to  exift  in  the  natural  world,  which  may  be  termed 
matter  and  fpirit,  as  propofed  in  Seel.  I.  and  further  treated  of  in 
Sect.  XIV.  The  efficient  eaufes  of  motion,  or  new  configura- 
tion, confift  either  of  the  principle  of  general  gravitation,  which 
actuates  the  fun  and  planets  ;  or  of  the  principle  of  particular 
gravitation,  as  in  electricity,  magnetifm,  heat ;  or  of  the  princi- 
ple of  chemical  affinity,  as  in  combuftion,  fermentation,  combi- 
nation ;  or  of  the  principle  of  organic  life,  as  in  the  contraction 
of  vegetable  and  animal  fibres.  The  inert  eaufes  of  motion,  or 
new  configuration,  confift  of  the  parts  of  matter,  which  are  in- 
troduced within  the  fpheres  of  activity  of  the  principles  above 
defcribed.  Thus,  when  an  apple  falls  on  the  ground,  the  prin- 
ciple of  gravitation  is  the  efficient  caufe,  and  the  matter  of  the 
apple-tree  the  inert  caufe.  If  a  bar  of  iron  be  approximated 
to  a  magnet,  it  may  be  termed  the  inert  caufe  of  the  motion, 
which  brings  thefe  two  bodies  into  contact  ;  while  the  magnetic 
principle  may  be  termed  the  efficient  caufe.  In  the  fame  man- 
ner the  fibres,  which  conftitute  the  retina,  may  be  called  the  in- 
ert caufe  of  the  motions  of  that  organ  in  vifion,  while  the  fen- 
forial  power  may  be  termed  the  efficient  caufe. 

3.  Another  more  common  diftribution  of  the  perpetual  chain 
of  eaufes  and  effects,  which  conftitute  the  motions,  or  chang- 
ing configurations,  of  the  natural  world,  is  into  active  and  paf- 
five.  Thus,  if  a  ball  in  motion  impinges  againft  another  ball  at 
reft,  and  communicates  its  motion  to  it,  the  former  ball  is  faid 
to  act,  and  the  latter  to  be  acted  upon.  In  this  fenfe  of  the 
words  a  magnet  is  faid  to  attract  iron  ;  and  the  prick  of  a  fpur 
to  ftimulate  a  horfe  into  exertion  ;  fo  that  in  this  view  of  the 
works  of  nature  all  things  may  be  faid  either  (imply  to  exift,  or 
to  exift  as  eaufes,  or  to  exift  as  effects  ;  that  is,  to  exift  either 
in  an  active  or  paffive  ftate. 

This  diftribution  of  objects  and  their  motions,  or  changes 
of  pofition,  has  been  found  fo  convenient  for  the  purpofes  of 
common  life,  that  on  this  foundation  re fts  the  whole  conftruc- 

tion 


44©  GENERATION.        SECT.  XXXIX.  12. 4, 

tion  or  theory  of  language.  The  names  of  the  things  them- 
felves  are  termed  by  grammarians  Nouns,  and  their  modes  of 
exiftence  are  termed  Verbs.  The  nouns  are  divided  into  fub- 
ftantives,  which  denote  the  principal  things  fpoken  of;  and  in- 
to adjectives,  which  denote  fome  circumftances,  or  lefs  kinds 
of  things,  belonging  to  the  former.  The  verbs  are  divided  into 
three  kinds,  fuch  as  denote  the  exiftence  of  things  (imply,  as,  to 
be ;  or  their  exiftence  in  an  a£tive  (late,  as,  to  eat ;  or  their  ex- 
iftence in  a  paflive  (late,  as,  to  be  eaten.  Whence  it  appears, 
that  all  languages  confift  only  of  nouns  and  verbs,  with  their 
abbreviations  for  the  greater  expedition  of  communicating  our 
thoughts  5  as  explained  in  the  ingenious  work  of  Mr.  Home 
Tooke,  who  has  unfolded  by  a  fmgle  fiafti  of  light  the  whole 
theory  of  language,  which  had  fo  long  lain  buried  beneath  the 
learned  lumber  of  the  fchools.  Diverfions  of  Purley.  Johnfon. 
London. 

4.  A  third  divifion  of  caufes  has  been  into  proximate  and  re- 
mote ;  thefe  have  been  much  fpoken  of  by  the  writers  on  med- 
ical fubje£ts,    but  without  fufficient  precision.     If  to  proximate 
and  remote  caufes  we  add  proximate  and  remote  effedts,  we 
{hall    include   four  links  of  the  perpetual  chain  of  caufation  ; 
which  will    be  more  convenient  for  the  difcuflion  of  many  phi- 
loibphical  fubjects. 

Thus  if  a  particle  of  chyle  be  applied  to  the  mouth  of  a  lac- 
teal veffel,  it  may  be  termed  the  remote  cauie  of  the  motions  of 
the  fibres,  which  compofe  the  mouth  of  that  lacleal  veflel  ;  the 
fenforial  power  is  the  proximate  caufe  ;  the  contraction  of  the 
fibres  of  the  mouth  of  the  veffel  is  the  proximate  effect  j  and 
their  embracing  the  particle  of  chyle  is  the  remote  effect  ;  and 
thefe  four  links  of  caufation  constitute  abforption. 

Thus  when  we  attend  to  the  rifing  fun,  firft  the  yellow  rays 
of  light  ftimulate  the  fenforial  power  refiding  in  the  extremities 
of  the  optic  nerve,  this  is  the  remote  caufe.  2-  The  fenforial 
power  is  excited  into  a  ftate  of  activity)  this  is  the  proximate 
caufe.  3.  The  fibrous  extremities  of  the  optic  nerve  are  con- 
tracted, this  is  the  proximate  effect.  4.  A  pleafurable  or  pain- 
ful fenfation  is  produced  in  coniequence  of  the  contraction  of 
thefe  fibres  of  the  opnc  nerve,  this  is  the  remote  effect  ;  and 
thefe  four  links  of  the  chain  of  caufation  conftitute  the  fenfi- 
tive  idea,  or  what  is  commonly  termed  the  ienfation  of  the  ri- 
fing fun. 

5.  Other  caufes  have  been  announced  by  medical  writers  un- 
der the  names  of  caufa  procatarctica,    and  caufa  proegumma, 
and  caufa  fine   qua  non.     All  which  are  links  more  or  lefs  dif- 
tant  of  the  chain  of  remote  caufes. 

To 


SECT.  XXXIX.  12.6.       GENERATION.  441 

To  thefe  mud  be  added  the  final  caufe,  fo  called  by  many  au- 
thors, which  means  the  motive,  for  the  accompliftiment  of  which 
the  preceding  chain  of  caufes  was  put  into  action.  The  idea 
of  a  final  caufe,  therefore,  includes  that  of  a  rational  mind, 
which  employs  means  to  effeft  its  purpofes;  thus  the  defire  of 
preferving  himfelf  from  the  pain  of  cold,  which  he  has  frequent- 
ly experienced,  induces  the  favage  to  conftrudl  his  hut  ;  the  fix- 
ing (takes  into  the  ground  for  walls,  branches  of  trees  for  rafters, 
and  turf  for  a  cover,  are  a  feries  of  fucceflive  voluntary  exer- 
tions ;  which  are  fo  many  means  to  produce  a  certain  effe£h 
This  effe£t  of  preferving  himfelf  from  cold,  is  termed  the  final 
caufe  ;  the  conitruftion  of  the  hut  is  the  remote  effect  ;  the  ac- 
tion of  the  mufcular  fibres  of  the  man,  is  the  proximate  effeft  ; 
the  volition,  or  activity  of  defire  to  preferve  himfelf  from  cold, 
is  the  proximate  caufe  ;  and  the  pain  of  cold,  which  excited 
that  defire,  is  the  remote  caufe. 

6.  This  perpetual  chain  of  caufes  and  effefts,  the  firft  link  of 
which  isrivetted  to  the  throne  of  God,  divides  itfelf  into  innu- 
merable diverging  branches,  which,  like  the  nerves  arifmg  from 
the  brain,  permeate  the  mod  minute  and  moil  remote  extremi- 
ties of  the  fyflem,  difFufing  motion  and  fenfarion  to  the  whole. 
As  every  caufe  is  luperior  in  power  to  the  effecfl,  which  it  has 
produced,  fo  our  idea  of  the  power  of  the  Almighty  Creator 
becomes  more  elevated  and  fublime,  as  we  trace  the  opera- 
tions of  nature  from  caufe  to  caufe,  climbing  up  the  links  of 
thefe  chains  of  being,  till  we  afcend  to  the  Great  Source  of  all 
things. 

Hence  the  modern  difcoveries  in  chemiftry  and  in  geology, 
by  having  traced  the  caufes  of  the  combinations  of  bodies  to 
remoter  origins,  as  well  as  thofe  in  aftronomy,  which  digni- 
fy the  prefent  age,  contribute  to  enlarge  and  amplify  our  ideas 
of  the  power  of  the  Great  Firft  Caufe.  And  had  thofe  ancient 
philofophers,  who  contended  that  the  world  was  formed  from 
atoms,  afcribed  their  combinations  to  certain  immutable  prop- 
erties received  from  the  hand  of  the  Creator,  fuch  as  general 
gravitation,  chemical  affinity,  or  animal  appetency,  inftead  of 
afcribing  them  to  a  blind  chance  ;  the  doftrine  of  atoms,  as  con- 
ftituting  or  compofing  the  material  world  by  the  variety  of  their 
combinations,  fo  far  from  leading  the  mind  to  atheifm,  would 
ftrengthen  the  demonilration  of  the  exiftence  of  a  Deity,  as  the 
firft  caufe  of  all  things  ;  bccaufe  the  analogy  refulting  from  our 
perpetual  experience  of  caufe  and  effeft  would  have  thus  been 
exemplified  through  univerfal  nature. 

The  heavens  declare  the  Glory  of  GOD,  and  the  firmament 
/heiveth  his  handy  work  !  One  day  telleth  another  >  and  one  night 

VOL.  I.  Iii  certifieth 


442  GENERATION.        SECT.  XXXIX.  1 2.  6. 

certifath  another  ;  they  have  neither  fpeech  nor  language ,  yet  their 
voice  is  gone  forth  into  all  lands ,  and  their  words  into  the  ends  of  the 
*tvorld.  Manifold  are  thy  works,  O  LORD  !  in  ivifdom  haft  thou 
made  them  all*  Pfal.  xix.  civ. 


SECT, 


SECT.  XL.  OCULAR  SPECTRA.  443 

SECT.      XL. 

On  the  OCULAR  SPFCTRA  of  Light  and  Colours,  by  Dr.  R.  W. 
Darwin  of  Shrewfbury.  Reprinted,  by  permiflion,  from  the 
Philofophical  Tranfadions,  Vol.  LXXVI.  p.  313. 

Speclra  of  four  kinds.  I.  Activity  of  the  retina  in  vifton.  2.  Spec- 
tra from  dejecl  of fenftbility*  3.  Speclra  from  excefs  of  fenfibili- 
ty.  4.  Of  direcl  ocular  fpeclra.  5.  Greater  Jliumulus  excites, 
the  retina  into  fpafmodic  aclion.  6.  Q/  reverfe  occuiar  fpeclra. 
7.  Greater  Jlimulus  excites  the  retina  into  various  fuccejfive  fpaf- 
modic aftions.  8.  Into  fixed  fpafmodic  aclion.  9.  Into  tempora- 
ry paralyKs.  10.  Mifcellaneous  remarks  ;  i.  Dire 51  and  re- 
<u  erf e  fpeclra  at  the  fame  time.  A  fpeclra  halo.  Rule  to  prede- 
termine the  colours  of  fpeclra  2  Variation  of  fpeclra  from  ex- 
traneous light.  3.  Variation  of  fpeclra  in  number  >  figure^  and 
remijjion.  4.  Circulation  of  the  blood  in  the  eye  is  vifible.  j.  A 
new  way  of  magnifying  objects.  Conclujion. 

WHEN  any  one  has  long  and  attentively  looked  at  a  bright 
objeft,  as  at  the  fetting  fun,  on  clofing  his  eyes,  or  removing 
them,  an  image,  which  refembles  in  form  the  object  he  was  at- 
tend, ng  to,  continues  fome  time  to  be  vifible  j  this  appearance 
in  the  eye  we  (hall  call  the  ocular  fpeclrum  of  that  object, 

Thefe  ocular  fpe^tra  are  of  four  kinds:  ift,  Such  as  are 
owin^  to  a  kfs  fenfibility  of  a  defined  part  of  the  retina  ;  or 
fpeftra  from  defecl  of  fenfibUity.  ad,  Such  as  are  owing  to  a 
greater  fenfibility  of  a  defined  part  of  the  retina  ;  or  fpeclra  from 
excefs  of  fenfibility  3d,  Such  as  refemble  their  objetfc  in  its 
colour  as  well  as  form  ;  which  may  be  termed  dirett  ocular  fpec- 
tm  4th,  Such  as  are  of  a  colour  contrary  to  that  of  their  objedt; 
which  may  be  termed  reverfe  ocular  fpeclra. 

The  laws  of  light  have  been  molt  fuccefsfully  explained  by 
the  great  Nekton,  and  the  perception  of  vifible  objects  has  been 
ably  inveftigated  by  the  ingenious  Dr.  Berkeley  and  M.  Maie- 
branche  ;  but  thefe  minute  phenomena  of  vifion  have  yet  been 
thought  reducible  to  no  theory,  though  many  philofophers  have 
employed  a  confiderable  degree  of  attention  upon  them  :  among 
thefe  are  Dr.  Jurin,  at  the  end  of  Dr.  Smith's  Optics ;  M. 
j£pinus,  in  the  Nov.  Com  Petropol.  V.  10  ;  M.  Beguelin,  in 
the  Berlin  Memoires,  V  II.  1771  ;  M.  d'Arcy,  in  the  Hiftoire 
de  T/Vcad  des  Scienc.  1765  ;  M.  de  la  Hire  ;  and,  laftly,  the 
celebrated  M.  de  BufFon,  in  the  Memoires  de  1'Acad.  des  Scien. 

who 


444  OCULAR  SECTRA.        SECT.  XL.  i.  i. 

who  has  termed  them  accidental  colours,  as  if  fubjefted  to  no 
eftablifhed  laws,  Ac,  Par.  1743    M   p.  215. 

I  muft  here  apprize  the  reader,  that  it  is  very  difficult  for  dif- 
ferent people  to  give  the  fame  name  to  various  (hades  of  colours  ; 
whence,  in  the  following  pages,  fomething  muft  be  allowed,  if 
on  repeating  the  experiments  the  colours  here  mentioned  (hould 
not  accurately  correfpond  with  his  own  names  of  them. 

I.  Aftivity  of  the  Retina  in  Vtfton. 

From  the  fubfequent  experiments  it  appears,  that  the  retina 
is  in  an  aftive  not  in  a  paflive  ftate  during  the  exiftence  of  thefc 
occular  fpedra  ;  and  it  is  thence  to  be  concluded,  that  all  vifion 
is  owing  to  the  aftivity  of  this  organ. 

1.  Place  a  piece  of  red  (ilk,  about  an  inch  in  diameter,  as  in 
plate  i,  at  Se6r.  III    i,  on  a  fheet  of  white  paper,  in  a  ftrong 
light  ;    look  fteadily  upon  it  from  about  the  diftance  of  half  a 
yard  for  a  minute  ;  then  clofing  your  eyelids  cover  them    wiih 
your  hands,  and  a  green  fpedlrum  will  be  feen  in  your  eyes,  re- 
fembling  in  form  the  piece  of  red  filk  :  after  fome  time,  this 
fpedlrum   will  difappear  and  (hortly  reappear  ;  and    this  alter- 
nately three  or  four  times,  if  the  experiment  is  well  made,  till  at 
length  it  vanifhes  entirely. 

2.  Place  on  a  (heet  of  white  paper  a  circular  piece  of  blue 
filk,  about  four  inches  in  diameter,  in  the  funfhine  •,  cover  the 
centre  of  this  with  a  circular  piece  of   yellow  (ilk,  about  three 
inches  in  diameter  ;  and  the  centre  of  the  yellow  filk  with  a  cir- 
cle of  pink  filk,  about  two  inches  in  diameter  ;  and  the  centre 
of  the  pink  filk  with  a  circle  of  green  (ilk,  about  one  inch   in 
diameter  ;  and  the  centre  of  this  with  a  circle  of  indigo,  about 
half  an  inch  in  diameter ;  make  a  fmall  fpeck  with  ink  in  the 
very  centre  of  the  whole,  as  in  plate  3,  at  Seft  III.  3.6.;  look 
fteadily  for  a  minute  on  this  central  fpot,  and  then  clofing  your 
eyes,  and  applying  your  hand  at  about  an  inch  diftance  before 
them,  fo  as  to  prevent  too  much  or  too  little  light  from  paffing 
through  the  eyelids,  you  will  fee  the  moft  beautiful  circles  of 
colours  that  imagination  can  conceive,  which  are  moft  refembled 
by  the  colours  occafioned  by  pouring  a  drop  or  two  of  oil  on  a 
dill  lake  in  a  bright  day ;  but  theie  circular  irifes  of  colours  arc 
not  only  different  from  the  colours  of  the  filks  above  mention- 
ed, but  are  at  the  fame  time  perpetually  changing  as  long  as 
they  exift. 

3.  When    any  one  in  the  dark  prefles  either  corner  of  his 
eye  with  his  finger,  and  turns  his  eye  away  from  his  finger,  he 
will  fee  a  circle  of  colours  like  thofe  in  a  peacock's  tail  :  and  a 

fudden 


SECT.  XL.  i.  4.         OCULAR  SPECTRA.  445 

fudden  flafli  of  light  is  excited  in  the  eye  by  a  ftroke  on  it, 
(Newton's  Opt  Q^i6.) 

4.  When  any  one  turns  round  rapidly  on  one  foot,  till  he 
becomes  dizzy,  and  falls  upon  the  ground,  the  fpeftra  of  the 
ambient  objects  continue  to  prefent  themfelves  in  rotation,  or 
appear  to  librate,  and  he  feems  to  behold  them  for  fome  time 
ftill  in  motion. 

From  all  thefe  experiments  it  appears,  that  the  fpeftra  in  the 
eye  are  not  owing  to  the  mechanical  impulfe  of  light  imprefled 
on  the  retina,  nor  to  its  chemical  combination  with  that  organ, 
nor  to  the  abforption  and  emiflion  of  light,  as  is  obferved  in 
many  bodies  ;  for  in  all  thefe  cafes  the  fpetlra  mud  either  re- 
main uniformly,  or  gradually  diminifh  ;  and  neither  their  alter- 
nate prefence  and  evanefcence  as  in  the  firft  experiment,  nor 
the  perpetual  changes  of  their  colours  as  in  the  fecond,  nor  the 
flam  of  light  or  colours  in  the  prefied  eye  as  in  the  third,  nor  the 
rotation  or  libration  of  the  fpetlra  in  the  fourth,  could  exift. 

It  is  not  abfurd  to  conceive,  that  the  retina  may  be  ftimulated 
into  motion,  as  well  as  the  red  and  white  mufcles  which  form 
our  limbs  and  veflels  ;  (ince  it  confifts  of  fibres,  like  thofe,  inter- 
mixed with  its  medullary  fubftance.  To  evince  this  ftrufture, 
the  retina  of  an  ox's  eye  was  fufpended  in  a  glafs  of  warm 
water,  and  forcibly  torn  in  a  few  places  ;  the  edges  of  thefe 
parts  appeared  jagged  and  hairy,  and  did  not  contract,  and  be- 
come fmooth  like  fimple  mucus,  when  it  is  diflencled  till  it 
breaks  •,  which  (hews  that  it  confifts  of  fibres  j  and  its  fibrous 
conftruftion  became  dill  more  diftindt  to  the  fight,  by  adding 
fome  cauftic  alkali  to  the  water,  as  the  adhering  mucus  was  firit 
eroded,  and  the  hair-like  fibres  remained  floating  in  the  veflel. 
Nor  does  the  degree  of  tranfparency  of  the  retina  invalidate  the 
evidence  of  its  fibrous  ftru&ure,  fince  Lceuwenhoek  has  (hewn 
that  the  cryftalline  humour  itfelf  confifts  of  fibres.  ( Arcana 
Naturae,  Vol.  I.  p.  70.) 

Hence  it  appears,  that  as  the  mufcles  have  larger  fibres  inter- 
mixed with  a  fmaller  quantity  of  nervous  medulla  the  organ  of 
vifion  has  a  greater  quantity  of  nervous  medulla  intermixed  with 
fmaller  fibres  ;  and  it  is  probable  that  the  locomotive  mufcles, 
as  well  as  the  vafcular  ones,  of  microfcopic  animals  have  much 
greater  tenuity  than  thofe  of  the  retina. 

And  befides  the  fimilar  laws,  which  will  be  (hewn  in  this 
paper  to  govern  alike  the  actions  of  the  retina  and  of  the  muf- 
cles, there  are  many  other  analogies  which  exift  between  them. 
They  are  both  originally  excited  into  action  by  irritations,  both 
aft  nearly  in  the  fame  quantity  of  time,  are  alike  ftrengthened 
or  fatigued  by  exertion,  are  alike  painful  if  excited  into  action 

when 


446  OCULAR  SPECTRA.        SECT.  XL.  2.  i. 

when  they  are  in  an  inflamed  ftate,  are  alike  liable  to  paralyfis, 
and  to  the  torpor  of  old  age. 

II.    OF    SPECTRA    FROM    DEFECT   OF    SENSIBILITY. 

The  retina  is  not  fo   eafily  excited  into  aElion  by   lefs  irritation  after 
having  been  lately  fubjeEted  to  greater. 

1 .  WHEN  any  one  pafTes  from  the  bright  day-light  into  a  dark- 
ened room,  the  irifes  of  his  eyes  expand  themfelves  to  their  ut- 
moft  extent  in  a  few  feconds  of  time  ;  but  it  is  very  long  before 
the  optic  nerve,  after  having  been  itimuiated  by  the  greater  light 
of  the  day,  becomes  fenfible  of  the  lefs  degree  of  it  in  the  room  ; 
and  if  the  room  is  not  too  obfcure,  the  irifes  will  again  contrail 
themfelves  in  fome  degree,  as  the  fenfibility  of  the  retina  returns. 

2.  Place  about  half  an  inch  fquare  of  white  paper  on  a  black 
hat,  and  looking  fteadily  on  the  centre  of  it  for  a  minute,  remove 
yoar  eyes  to  a  (heet  of  white  paper  ;  and  after  a  fecond  or  two 
a  dark  fquare  will  be  feen  on  the  white  paper,    which  will  con- 
tinue fome  time.      A  fimilar   dark  fquare  will  be  feen    in  the 
clofed  eye,  if  light  be  admitted  through  the  eyelids. 

So  after  looking  at  any  luminous  object  of  a  fmall  fize,  as  at 
the  fun  for  a  (hort  time,  fo  as  not  much  to  fatigue  the  eyes, 
this  part  of  the  retina  becomes  lefs  fenfibie  to  fmaller  (Quantities 
of  light  ;  hence,  when  the  eyes  are  turned  on  other  lefs  lumi- 
nous parts  of  *he  iky,  a  dark  fpot  is  feen  refembling  the  fhape  of 
the  fun,  or  other  luminous  objeft  which  we  lair,  beheld.  This 
is  the  four'ce  of  one  kind  of  the  dark-coloured  mufca  volitantes. 
If  this  dark  fpot  lies  above  the  centre  of  the  eye,  we  turn  our  eyes 
that  way  c  xpefting  to  bring  it  into  the  centre  of  the  eye,  that  we 
may  view  it  more  diftindlly  ;  and  in  this  cafe  the  dark  fpetlrum 
feems  to  move  upwards.  If  the  dark  fpectrum  is  found  beneath 
the  centre  of  the  eye,  we  purfue  it  from  the  fame  motive,  and  it 
fcems  to  move  downwards.  This  has  given  rife  to  various  con- 
jectures of  fomething  floating  in  the  aqueous  humours  of  the 
e^s  ;  but  whoever,  in  attending  to  thefe  fpots,  keeps  his 
eyes  unmoved  by  looking  fteadily  at  the  corner  of  a  cloud,  at 
the  fame  time  that  he  obferves  the  dark  ipeftra,  will  be  thor- 
oughly convinced,  that  they  have  no  motion  but  what  is  given 
to  them  by  the  movement  of  our  eyes  in  purfuit  of  them.  Some- 
times the  form  of  the  fpedtrum,  when  it  has  been  received  from 
a  circular  luminous  body,  will  become  oblong  ;  and  fometinies 
it  will  be  divided  into  two  circular  fpeftra,  which  is  not  owing 
to  our  changing  the  angle  made  by  the  two  optic  axifes,  accord- 
ing to  the  inftance  of  the  clouds  or  other  bodies  to  which  the 

fpe&rum 


SECT.  XL.  2. 3.        OCULAR  SPECTRA.  447 

fpeftrum  is  fuppofed  to  be  contiguous,  but  toother  caufes  men- 
tioned in  No.  X  3.  of  this  feftion.  The  apparent  fize  of  it 
will  alfo  be  variable  according  to  its  fuppofed  dillance. 

As  thefe  fpeftra  are  more  eafily  obfervable  when  our  eyes  are 
a  little  weakened  by  fatigue,  it  has  frequently  happened,  that  peo- 
ple of  delicate  conftitutions  have  been  much  alarmed  at  them, 
fearing  a  beginning  decay  of  their  fight,  and  have  thence  fallen 
into  the  hands  of  ignorant  oculifls  •,  but  I  believe  they  never  are 
a  prelude  to  any  other  difeafe  of  the  eye,  and  that  it  is  from 
habit  alone,  and  ou»-  want  of  attention  to  them,  that  we  do  not 
fee  them  on  all  objects  every  hour  of  our  lives.  But  as  the 
nerves  of  very  weak  people  lofe  their  fenfibility,  in  the  fame 
manner  as  their  mufcles  lofe  their  activity,  by  a  fmall  time  of 
exertion,  it  frequently  happens,  that  fick  people  in  the  extreme 
debility  of  fevers  are  perpetually  employed  in  picking  fome- 
thing  from  the  bed-clothes,  occafioned  by  their  miftaking  the 
appearance  of  thefe  mufca  volitantes  in  their  eyes.  Benvenuto 
Celini,  an  Italian  artift,  a  man  of  ftrong  abilities,  relates,  that 
having  pafied  the  whole  night  on  a  diftant  mountain  with  fome 
companions  and  a  conjurer,  and  performed  many  ceremonies  to 
raife  the  devil,  on  their  return  in  the  morning  to  Rome,  and 
looking  up  when  the  fun  began  to  rife,  they  faw  numerous  dev- 
ils run  on  the  tops  of  the  houfes,  as  they  pafled  along  ;  fo  much 
were  the  fpeftra  of  their  weakened  eyes  magnified  by  fear,  and 
made  fub'ervient  to  the  purpofes  of  fraud  or  fuperftition.  (Life 
of  Ben.  Celini.) 

3  Place  a  fquare  inch  of  white  paper  on  a  large  piece  of 
ftraw-coloured  filk;  look  (teadily  fornet  me  on  the  white  paper, 
and  then  move  the  centre  of  your  eyes  on  the  filk,  and  a  fpec- 
trum  of  the  form  of  the  paper  will  appear  on  the  filk,  of  a  deep- 
er yellow  than  the  other  part  of  it  :  for  the  cenrral  part  of  the 
retina,  having  been  fome  timeexpofed  to  the  tlimulus  of  a  greater 
quantity  of  white  light,  is  become  lefs  fenfible  to  a  fmaller  quan- 
tity of  it,  and  therefore  fees  only  the  yellow  rays  in  that  part  of 
the  ftraw-coloured  filk. 

Facls  fimilar  to  thefe  are  obfervable  in  other  parts  of  our 
fyftem  :  thus,  if  one  hand  be  made  warm,  and  the  other  expofed 
to  the  cold,  and  then  both  of  them  immerfed  in  fubtepid  water, 
the  water  is  perceived  warm  to  one  hand,  and  cold  to  the  other  ; 
and  we  are  not  able  to  hear  weak  founds  for  fome  time  after  we 
have  been  expofed  to  loud  ones  -,  and  we  feel  a  chillinefs  on  com- 
ing into  an  atmofphere  of  temperate  warmth,  after  having  been 
fome  time  confined  in  a  very  warm  room :  and  hence  the  ftom- 
ach,  and  other  organs  of  digeftion,  of  thofe  who  have  been  ha- 
bituated to  the  greater  ftimulus  of  fpirituous  liquor,  are  not  ex- 
cited 


448  OCULAR  SPECTRA.        SECT.  XL.  3.  i. 

cited  into  their  due  a&ionby  thelefs  ftimulus  of  common  food 
alone ;  of  which  the  immediate  confequence  is  indigeftion  and 
hypochondriacifm. 

III.    OF    SPECTRA  FROM  EXCESS  OF  SENSIBILITY. 

The  retina  is  more  eqfily  excited  into  aEiion  by  greater  irritation  after 
having  been  lately  fubjeuled  to  lefs. 

1 .  IF  the  eyes  are  clofed,  and  covered  perfeftly  with  a  hat, 
for  a  minute  or  two,  in  a  bright  day  ;  on  removing   the  hat  a 
red  or  crimfon  light  is  feen  through  the  eyelids.     In  this  exper- 
iment the  retina,  after  being  fome  time  kept  in  the  dark,  becomes 
fo  fenfible  to  a  fmall  quantity  of  light,  as  to  perceive  diftindlly 
the  greater  quantity  of  red  rays  than  of  others  which  pafs  through 
the  eyelids.     A  (imilar  coloured  light  is  feen  to  pafs  through  the 
edges  of  the  fingers,  when  the  open  hand  is  oppofed  to  the  flame 
of  a  candle. 

2.  If  you  look  for  fome  minutes  fteadily  on  a  window  in  the 
beginning  of  the  evening  twilight,  or  in  a  dark  day,  and   then 
move  your  eyes  a  little,  fo  that  thofe  parts   of  the  retina,   on 
which  the  dark  frame-work  of  the  window  was  delineated,  may 
now  fall   on   the  glafs  part  of  it,  many  luminous  lines,  repre- 
fenting  the  frame- work,  will  appear  to  lie  acrofs  the  glafs  panes: 
for  thofe  parts  of  the  retina,  which  were  before  lead  ftimulated, 
by  the  dark  frame- work,  are  now  more  fenfible  to  light  than  the 
other  parts  of  the  retina  which  were  expofed  to  the  more  lu- 
minous parts  of  the  window. 

3.  Make  with  ink  on  white  paper  a  very  black   fpot,  about 
half  an  inch  in  diameter,  with  a  tail  about  an  inch  in  length,  fo 
as  to  reprefent  a  tadpole,  as  in  plate  2,  at  Se£fc.  III.  8.  3  ;  look 
(leadily  for  a  minute  on  this  fpot,  and,  on  moving  the  eye  a  lit- 
tle, the  figure  of  the  tadpole  will  be  feen  on  the  white  part  of 
the  paper,    which  figure  of  the  tadpole  will   appear  whiter  or 
more  luminous  than  the  other  parts  of  the  white  paper  ;  for  the 
part  of  the  retina  on  which  the  tadpole  was  delineated,  is  now 
more  fenfible  to  light  than  the  other  parts  of  it,  which  were  ex- 
pofed to  the  white  paper.     This  experiment  is   mentioned  by 
Dr.  Irwin,  but  is  not  by  him  afcribed  to  the  true  caufe,  namely, 
the  greater  fenfibility  of  that  part  of  the  retina  which  has  been 
expofed  to  the  black  fpot,  than  of  the  other  parts  which  had  re- 
ceived the  white  field  of  paper,  which  is  put  beyond  a  doubt  by 
the  next  experiment. 

4.  On  clofing  the  eyes  after  viewing  the  black  fpot  on  the 
white  paper,  as  in  the  foregoing  experiment,  a  red  fpot  is  feen 

of 


SECT.  XL.  3.  5.        OCULAR  SPECTRA.  449 

of  the  form  of  the  black  fpot :  forthat  partof  theretina,  on  which 
the  black  fpot  was  delineated,  being  now  more  fenfible  to  light 
than  the  other  parts  of  it,  which  were  expofed  to  the  white  pa- 
per, is  capable  of  perceiving  the  red  rays  which  penetrate  the 
eyelids.  If  this  experiment  be  made  by  the  light  of  a  tallow 
candle,  the  fpot  will  be  yellow  inftead  of  red  \  for  tallow  can- 
dles abound  much  with  yellow  light,  which  pafles  in  greater 
quantity  and  force  through  the  eyelids  than  blue  light  ;  hence 
the  difficulty  of  diflinguifhing  blue  and  green  by  this  kind  of 
candle  light.  The  colour  of  the  fpe&rum  may  poflibly  vary  in 
the  daylight,  according  to  the  different  colour  of  the  meridian 
or  the  morning  or  evening  light. 

M.  Beguelin,  in  the  Bt-rlin  Memoires,  V.  II.  1771,  obferves, 
that  when  he  held  a  book  fo  that  the  fun  (hone  upon  his  half- 
clofed  eyelids,  the  black  letters,  which  he  had  long  infpecled, 
became  red,  which  mult  have  been  thus  occafioned.  Thofe 
parts  of  the  retina  which  had  received  for  fome  time  the  black 
letters,  were  fo  much  more  fenfible  than  thole  parts  which  had 
been  oppofed  to  the  white  paper,  that  to  the  former  the  red 
light,  which  patted  through  the  eyelids,  was  perceptible  There 
is  a  fimilar  ftory  rold,  I  think,  in  M.  de  Voltaire's  Hiflorical 
Works,  of  a  Duke  of  fufcany,  who  was  playing  at  dice  with 
the  general  of  a  foreign  army,  and,  believing  he  faw  bloody 
fpots  upon  the  dice,  portended  dreadful  events,  and  retired  in 
confufion.  The  obierver,  after  looking  for  a  minute  on  the 
black  fpots  of  a  die,  and  careiefsly  clofing  his  eyes,  on  a  bright 
day,  would  fee  the  image  of  a  die  with  red  fpots  upon  it,  as 
above  explained 

5.  On  emerging  from  a  dark  cavern,  where  we  have  long 
continued,  the  light  of  a  bright  day  becomes  intolerable  to  the 
eye  for  a  confiderable  time,  owing  to  the  excefs  of  fenfibility  ex- 
iiting  in  the  eye,  after  having  been  long  expofed  to  little  or  no 
ftimulus.  This  occafions  u?»  immediately  to  contract  the  iris  to 
its  fmalleft  aperture,  which  becomes  again  gradually  dilated,  as 
the  retina  becomes  accultomed  to  the  greater  ftimulus  of  the 
daylight. 

The  twinkling  of  a  bright  ftar,  or  of  a  diftant  candle  in  the 
night,  is  perhaps  owing  to  the  fame  caufe.  While  we  continue 
to  look  upon  thefe  luminous  objects,  their  central  parts  gradu- 
ally appear  paler,  owing  to  the  decreafing  fenfibility  of  the  part 
of  the  retina  expofed  to  their  light  *,  whilft,  at  the  fame  time, 
by  the  unfteadinefs  of  the  eye,  the  edges  of  them  are  perpetually 
falling  on  parts  of  the  retina  that  were  juft  before  expofed  to 
the  darknefs  of  the  night,  and  therefore  tenfold  more  fenfible  to 
light  than  the  part  on  which  the  ftar  or  candle  had  been  for 

VOL.  I.  K  K  k  fomr 


450  OCULAR  SPECTRA.        SECT.  XL.  4.  i, 

fome  time  delineated.  This  pains  the  eye  in  a  fimilar  manner 
as  when  we  come  fuddenly  from  a  dark  room  into  bright  day- 
light, and  gives  the  appearance  of  bright  fcintillations.  Hence 
the  ftars  twinkle  moft  when  the  night  is  darkeft,  and  do  not 
twinkle  through  telefcopes,  as  obferved  by  Mufchenbroeck  j  and 
it  will  afterwards  be  feen  why  this  twinkling  is  fometimes  of 
different  colours  when  the  object  is  very  bright,  as  Mr.  Melvill 
obferved  in  looking  at  Sirius.  For  the  opinions  of  others  on 
this  fubjedt,  fee  Dr.  Prieftley's  valuable  Hiftory  of  Light  and 
Colours,  p.  494. 

Many  fads  obfervable  in  the  animal  fyftem  are  fimilar  to 
thefe ;  as  the  hot  glow  occafioned  by  the  ufual  warmth  of  the 
air,  or  our  clothes,  on  coming  out  of  a  cold  bath  ;  the  pain  of 
the  fingers  on  approaching  the  fire  after  having  handled  fnow  ; 
and  the  inflamed  heels  from  walking  in  fnow.  Hence  thofe 
who  have  been  expofed  to  much  cold  have  died  on  being  brought 
to  a  fire,  or  their  limbs  have  become  fo  much  inflamed  as  to 
mortify.  Hence  much  food  or  wine  given  fuddenly  to  thofe 
who  have  almoft  periftied  by  hunger  has  deflroyed  them  ;  for 
all  the  organs  of  the  famifhed  body  are  now  become  fo  much 
more  irritable  to  the  ftimulus  of  food  and  wine,  which  they 
have  long  been  deprived  of,  that  inflammation  is  excited,  which 
terminates  in  gangrene  or  fever. 

IV.   OF   DIRECT   OCULAR   SPECTRA. 

A  quantity  of  Jlimulus  fomewhat  greater  than   natural  excites  tht 
retina  into  fpafmodic  acllony  which  ceafes  in  afeiv  feconds. 

A  CERTAIN  duration  and  energy  of  the  ftimulus  of  light 
and  colours  excites  the  perfect  aftion  of  the  retina  in  vifion  ; 
for  very  quick  motions  are  imperceptible  to  us,  as  well  as  very 
flow  ones,  as  the  whirling  of  a  top,  or  the  fhadowon  a  fun-dail. 
So  perfect:  darknefs  does  not  affect  the  eye  at  all  j  and  excefs 
of  light  produces  pain,  not  vifion. 

i.  When  a  fire-coal  is  whirled  round  in  the  dark,  a  lucid  cir- 
cle remains  a  confiderable  time  in  the  eye  •,  and  that  with  fo 
much  vivacity  of  light,  that  it  is  miftaken  for  a  continuance  of 
the  irritation  of  the  object.  In  the  fame  manner,  when  a  fiery 
meteory  (hoots  acrofs  the  night,  it  appears  to  leave  a  long  lucid 
train  behind  it,  part  of  which,  and  perhaps  fometimes  the  whole, 
is  owing  to  the  continuance  of  the  aftion  of  the  retina  after 
having  been  thus  vividly  excited.  This  is  beautifully  illuftrated 
by  the  following  experiment  :  fix  a  paper  fail,  three  or  four 
inches  in  diameter,  and  made  like  that  of  a  fmoke  jack,  in  a  tube 

of 


SECT.  XL.  4.  2.        OCULAR  SPECTRA.  451 

of  pafteboard  ;  on  looking  through  the  tube  at  a  diftant  prof- 
pe£r,  fome  disjointed  parts  of  it  will  be  feen  through  the  nar- 
row intervals  between  the  fails ;  but  as  the  fly  begins  to  revolve 
thefe  intervals  appear  larger  ;  and  when  it  revolves  quicker,  the 
whole  profpeft  is  feen  quite  asdiftincl  as  if  nothing  intervened, 
though  lefs  luminous. 

2.  Look  through   a  dark  tube,  about  half  a  yard  long,  at  the 
area  of  a  yellow  circle  of  a  half  an  inch  diameter,  lying  upon  a 
blue  area  of  double  that  diameter,   for  half  a  minute  ;  and  on 
clofing  your  eyes  the  colours  of  the  fpeclrum  will  appear  fimilar 
to  the  two  areas,   as  in   fig.  3.  ;  but  if  the  eye  is  kept  too  long 
upon  them,  the  colours  of  the  fpeclrum  will  be  the  reverfe  of 
thofe  upon    the  paper,  that  is,  the  internal  circle  will  become 
blue,  and  the  external  area  yellow  ;  hence  fome  attention  is  re- 
quired in  making  this  experiment. 

3.  Place  the  bright  flame  of  a  fpermaceti  candle  before  a  black 
object  in  the  night  ;  look  ileadily  at  it  for  a  (hort  time,  till  it  is 
obferved  to  become  fomewhat  paler  •,  and  on  clofing  the  eyes, 
and  covering  them  carefully,  but  not  ib  as  to  comprefs  them,  the 
image  of  the  blazing  candle  will  continue  diftinetly  to  be  vitlble, 

Look  ileadily,  for  a  fhort  time,  at  a  window  in  a  dark  day,  as 
inExp.  2.  Seel.  III.  and  then  clofing  your  eyes,  and  covering 
them  with  your  hands,  an  exact  delineation  of  the  window  re- 
mains for  fome  time  vifible  in  the  eye.  This  experiment  re- 
quires a  little  practice  to  make  it  fucceed  well ;  fince,  if  the 
eyes  are  fatigued  by  looking  too  long  on  the  window,  or  the  day 
be  too  bright,  the  luminous  parts  of  the  window  will  appear 
dark  in  the  fpectrum,  and  the  dark  parts  of  the  frame- work  will 
appear  luminous,  as  in  Exp.  2.  Seel.  III.  And  it  is  even  diffi- 
cult for  many,  who  firft  try  this  experiment,  to  perceive  the 
fpeelrum  at  all  ;  for  any  hurry  of  mind,  or  even  too  great  atten- 
tion to  the  fpeclrum  itfelf,  will  difappoint  them,  till  they  have 
had  a  little  experience  in  attending  to  fuch  fmall  fenfations. 

The  fpeetra  defcribed  in  this  feelion,  termed  direct  ocular 
fpeetra,  are  produced  without  much  fatigue  of  the  eye  ;  the  ir- 
ritation of  the  luminous  objeet  being  foon  withdrawn,  or  its 
quantity  of  light  being  not  fo  great  as  to  produce  any  degree  of 
uneafmefs  in  the  organ  of  vifion  ;  which  diftinguifhes  them 
from  the  next  clafs  of  ocular  fpeclra,  which  are  the  confequence 
of  fatigue.  Thefe  diredl  fpeclra  are  belt  obferved  in  fuch  cir- 
cumftances  that  no  light,  but  what  comes  from  the  objeet,  can 
fall  upon  the  eye  ;  as  in  looking  through  a  tube,  of  half  a  yard 
long,  and  an  inch  wide,  at  a  yellow  paper  on  the  fide  of  a  room, 
the  direct  fpectrum  was  eafily  produced  on  clofing  the  eye  with- 
out taking  it  from  the  tube  5  but  if  the  lateral  light  is  admitted 

through 


452  OCULAR  SPECTRA.        SECT.  XL.  5.  i. 

through  the  eyelids,  or  by  throwing  the  fpedrum  on*  white 
paper,  it  becomes  a  reverfe  fpedrum,  as  wiJl  be  explained  be- 
low. 

The  other  fenfes  alfo  retain  for  a  time  the  impreflions  that 
have  been  made  upon  them,  or  the  actions  they  have  been  ex- 
cited into.  So  if  a  hard  body  is  prefled  upon  the  palm  of  the 
hand,  as  is  pradifed  in  tricks  of  legerdemain,  it  is  not  eafy  to 
diftinguim  for  a  few  feconds  whether  it  remains  or  is  removed  ; 
and  taftes  continue  long  to  exift  vividly  in  the  mouth,  as  the 
fmoke  of  tobacco,  or  the  tafte  of  gentian,  after  the  fapid  mate- 
rial is  withdrawn. 

V.  A  quantity  cfjlimulusfome'what  greater  than  the  lajl  mentioned 
excites  the  retina  into  fpafmodic  aclion,  ivhich  ceafes  and  recurs 
alternately. 

1.  ON  looking  for  a  time  on  the  fetting  fun,  fo  as  not  great- 
ly to  fatigue  the  fight,  a  yellow  fpeflrum  is  feen  when  the  eyes 
are  clofed  and  covered,  which   continues  for  a   time,  and  then 
difappears  and    recurs  repeatedly  before    it  entirely  vanifhes. 
This  yellow  fpeftrum  of  the  fun  when  the  eyelids  are  opened 
becomes  blue  ;  and  if  it  is  made  to  fall  on  the  green  grafs,  or  on 
other  coloured  objects,  it  varies  its  own  colour  by  an  intermix- 
ture of  theirs,  as  will  be  explained  in  another  place. 

2.  Pla.ce  a  lighted  fpermaceti    candle  in  the  night  about  one 
foot  from  your  eye,  and  look  fleadily  on  the  centre  of  the  flame, 
till  your  eye  becomes  much   more  fatigued  than  in  Seft.  IV. 
Exp.  3.  ;  and  on  clofing  your  eyes  a  reddifh  fpectrum  will  be 
perceived,  which  will  ceafe  and  return  alternately. 

The  action  of  vomiting  in  like  manner  ceafes,  and  is  renew- 
ed by  intervals,  although  the  emetic  drug  is  thrown  up  with  the 
firil  effort ;  fo  after-pains  continue  fome  time  after  parturition  ; 
and  the  alternate  pulfations  of  the  heart  of  a  viper  are  renew- 
ed for  fome  time  after  it  is  cleared  from  its  blood. 

VI.    OF    REVERSE  OCULAR    SPECTRA. 

The  retina,  after  having  been  excited  into  aclion  by  a  Jlimulus  fome- 
•what  greater  than  the  I  aft  mentioned \  falls  into  oppofite  fpafmodic 
aclion. 

THE  actions  of  every  part  of  animal  bodies  may  be  advanta- 
geoufly  compared  with  each  other.  This  ftrict  analogy  con- 
tributes much  to  the  inveftigation  of  truth  ;  while  thole  loofer 
analogies,  which  compare  the  phenomena  of  animal  life  with 

thofe 


SECT.  XL.  6.  r.        OCULAR  SPECTRA,  453 

thofe  of  chemiftry  or  mechanics,  only  ferve  to  miflead  our  in- 
quiries. 

When  any  of  our  larger  mufcles  have  been  in  long  or  in  vio- 
lent aclion,  and  their  antagonifts  have  been  at  the  fame  time 
extended,  as  foon  as  the  aftion  of  the  former  ceafes,  the  limb  is 
ftretched  the  contrary  way  for  our  eafe,  and  a  pandiculation  or 
yawning  takes  place. 

By  the  following  observations  it  appears,  that  a  fimilar  cir- 
cumftance  obtains  in  the  organ  of  vifion  ;  after  it  has  been  fa- 
tigued by  one  kind  of  aftion,  it  fpontaneoufly  falls  into  the  op- 
pofire  kind. 

1 .  Place   a  piece  of  coloured  filk,  about  an  inch  in  diameter, 
on  a    fheet  of    white  paper,  about  half  a  yard  from  your  eyes  j 
look  fteadily  upon  it  fo<  a  minu  e  ;   then  remove  your  eyes  up- 
on another  part  of  the  white  paper,  and  a  fpeclrum  will  be  feen 
of  rhe  form  of  the  filk  thus  inflected,  but  of  a  colour  nppofite 
to  it.     A   Ipeclrum  nearly  fimilar  will  appear  if  the  eyeb  are 
clofed,  and  the   eyelids  (haded  by  approaching  the  hand  near 
them,  fo   as  to  permit  fome,  but  to  prevent  too  much  light  fall- 
ing on  them.  * 

Red  filk  produced  a  green  fpeftrum. 

Green  produced  a  red  one. 

Orange  produced    blue. 

Blue  produced  orange. 

Yellow  produced  violet. 

Violet  produced  yellow. 

That  in  thefe  experiments  the  colours  of  the  fpe£ra  are  the 
reverfe  of  the  colour^  which  occafioned  them,  may  be  feen  by 
examining  the  third  figjre  in  Sir  Ilaac  Newton's  Optics,  L.  II. 
p.  i.  where  thofe  thin  laminae  of  air,  which  reflected  yellow, 
tranfmitted  violet ;  thofe  which  reflected  red,  tranfmitted  a  blue 
green  ;  and  fo  of  the  reft,  agreeing  with  the  experiments  above 
related. 

2.  Thefe  reverfe  fpeftra  are  fimilar  to  a  colour,  formed  by  a 
combination  of  all  the  primary  colours  except  that  with  which 
the  eye  has  been  fatigued  in  making  the  experiment  :  thus  the 
reverfe  fpeclrum  of  red  muft  be  fuch  a  green  as  would  be  pro- 
duced by  a  combination  of  all  the  other  prifmatic  colours.     To 
evince  this  fa£l  the  following  fatisfaftory  experiment  was  made. 
The  prifmatic  colours  were  laid  on  a  circular  pafteboard  wheel, 
about  four  inches   in  diameter,  in  the  proportions  defcribed  in 
Dr  Prieftley's  hiftory  of  Light  and  Colours,  pi.    !2.  fig.  83.  ex- 
cept that  the  red  compartment  was  entirely  left  out,  and  the 
others  proportionably    extended   fo  as  to  complete  the  circle. 
Then,  as  the  orange  is  a  mixture  of  red  and  yellow,  and  as  the 

violet 


454  OCULAR  SPECTRA.         SECT.  XL.  6. 3. 

violet  is  a  mixture  of  red  and  indigo,  it  became  neceflary  to  put 
yellow  on  the  wheel  inftead  of  orange,  and  indigo  inftead  of  vi- 
olet, that  the  experiment  might  more  exactly  quadrate  with  the 
theory  it  was  defigned  to  eltablifh  or  confute  ;  becaufe  in  gam- 
ing a  green  fpettrum  from  a  red  objeft,  the  eye  is  fuppofed  to 
have  become  infenfible  to  red  light.  This  wheel,  by  means  of 
an  axis,  was  made  to  whirl  like  a  top  ;  and  on  its  being  put  in 
jmotion,  a  green  colour  was  produced,  correfponding  with  great 
cxa£tnefs  to  the  reverfe  fpeftrum  of  red. 

3.  In  contemplating  any  one  of  thefe  reverfe  fpeftra  in  the 
clofed  and  covered  eye,  it  disappears  and  reappears  feveral  times 
fucceflively,  till  at  length  it  entirely  vanilhes,  like  the  direft 
fpeclra  in  Se&.  V.  ;  but  with  this  additional  circumftance,  that 
when  the  fpeftrum  becomes  faint  or  evanefcent,  it  is  inftantly 
revived  by  removing  the  hand  from  before  the  eyelids,  fo  as  to 
admit  more  light :  becaufe  then  not  only  the  fatigued  part  of 
the  retina  is  inclined  fpontaneoufly  to  fall  into  motions  of  a 
contrary  direftion,  but  being  ftill  fenfible  to  all  other  rays  of 
light,  except  that  with  which  it  was  lately  fatigued,  is  by  thefe 
rays  at  the  fame  time  ftimulated  intothofe  motions  which  form 
the  reverfe  fpedrum. 

From  thefe  experiments  there  is  reafon  to  conclude,  that  the 
fatigued  part  of  the  retina  throws  itfelf  into  a  contrary  mode  of 
a£Hon,  like  ofcitation  or  pandiculation,  as  foon  as  the  ftimulus 
which  has  fatigued  it  is  withdrawn ;  and  that  it  flill  remains 
fenfible,  that  is,  liable  to  be  excited  into  aflion  by  any  other  col- 
ours at  the  fame  time,  except  the  colour  with  which  it  has  been 
fatigued. 

VII.  The  retina,  after  having  been  excited  into  aElkn  by  ajlimulus 
fomenvhat  greater  than  the  loft  mentioned \  falls  into  various  fuc- 
cejfive  fpafmodic  aflions. 

? .  ON  looking  at  the  meridian  fun  as  long  as  the  eyes  can 
well  bear  its  brightnefs,  the  difk  firft  becomes  pale,  with  a  lu- 
minous crefcent,  which  feems  to  librate  from  one  edge  of  it  to 
the  other,  owing  to  the  unfteadinefs  of  the  eye  -,  then  the  whole 
phafis  of  the  fun  becomes  blue,  furrounded  with  a  white  halo  ; 
and  on  clofmg  the  eyes,  and  covering  them  with  the  hands,  a 
yellow  fpedlrum  is  feen,  which  in  a  little  time  changes  into  a 
blue  one. 

M.  de  la  Hire  obferved,  after  looking  at  the  bright  fun,  that 
the  impreflion  in  his  eye  firft  aiTumed  a  yellow  appearance,  and 
then  green,  and  then  blue  ;  and  wifhas  to  afcribe  thefe  appear- 
ances to  fome  aiTeQion  of  the  nerves.  (Porterfield  on  the  Eye, 
Vol.  L  p.  343.)  2.  After 


SECT.  XL.  7.  2.        OCULAR  SPECTRA.  45$ 

2.  After  looking  fteadily  on  about  an  inch  fquare  of  pink  filk, 
placed  on  white  paper,  in  a  bright  funfhine,  at  the  diftance  of 
a  foot  from  my  eyes,  and  clofing  and  covering  my  eye-lids,  the 
fpeclrum  of  the  filk  was  at  firfl  a  dark  green,  and  the  fpeftrum 
of  the  white  paper  became  of  a  pink.  The  fpeclra  then  both 
difappeared  ;  and  then  the  internal  fpedlrumwas  blue;  and  then, 
after  a  fecond  difappearance,  became  yellow,  and  laftly  pink, 
whilft  the  fpeftrum  of  the  field  varied  into  red  and  green. 

Thete  fucceflions  of  different  coloured  fpeftra  were  notexadt- 
ly  the  fame  in  the  different  experiments,  though  obferved,  as 
near  as  could  be,  with  the  fame  quantity  of  light  and  other  fim- 
ilar  circumflances  ;  owing,  I  fuppofe,  to  trying  too  many  exper- 
iments at  a  time  *,  fo  that  the  eye  was  not  quite  free  from  the 
fpeftra  of  the  colours  which  were  previoufly  attended  to. 

The  alternate  exertions  of  the  retina  in  the  preceding  feftion 
refembled  the  ofcitation  or  pandiculation  of  the  mufcles,  as  they 
were  performed  in  directions  contrary  to  each  other,  and  were 
the  confequence  of  fatigue  rather  than  of  pain.  And  in  this  they 
differ  from  the  fucceflive  diflimilar  exertions  of  the  retina,  men- 
tioned in  this  fe&ion,-  which  refemble  in  miniature  the  more 
violent  agitations  of  the  limbs  in  convulfive  difeafes,  asepilepfy, 
chorea  S.  Viti,  and  opifthotonos  ;  all  which  difeafes  are  perhaps 
at  firft,  the  confequence  of  pain,  and  have  their  periods  after- 
wards eftablifhed  by  habit. 


VIIL   The  retina,  after  having  been  excited  into  action  by  a 
fomewhat  greater  than  the  lajl  mentioned^  jails  into  afixedfyaf- 
modic  aclion,  which  continues  for  feme  days*. 

i.  AFTER  having  looked  long  at  the  meridian  fun,  in  making 
fome  of  the  preceding  experiments,  till  the  difk  faded  into  a 
pale  blue,  I  frequently  obferved  a  bright  blue  fpeclrum  of  the 
fun  on  other  objects  all  the  next  and  the  fucceeding  day,  which 
conftantly  occured  when  I  attended  to  it,  and  frequently  when 
I  did  not  previoufly  attend  to  it.  When  I  clofed  and  covered 
my  eyes,  this  appeared  of  a  dull  yellow  ;  and  at  other  times  mix- 
ed with  the  colours  of  other  objects  on  which  it  was  thrown. 
It  may  be  imagined,  that  this  part  of  the  retina  was  become  in- 
fenfible  to  white  light,  and  thence  a  bluifh  fpeclrum  became  vif- 
ible  on  all  luminous  objects;  but  asayellowiQi  fpeftrum  was  alfo 
feen  in  the  clofed  and  covered  eye,  there  can  remain  no  doubt 
of  this  being  the  fpeclrum  of  the  fun.  A  fimilar  appearance 
was  obferved  by  M.  ./Epinus,  which  he  acknowledges  he  could 
give  no  account  of.  (Nov.  Com.  Petrop.  V.  10.  p.  2.  and  o.} 

The  locked  jaw,  and  fome  cataleptic  fpafms,  are  refembled  by 

this  " 


456  OCULAR  SPECTR  A.         SECT.  XL.  9.  i . 

this  phenomenon  j  and  from  hence  we  may  learn  the  danger  to 
the  eye  by  infpecting  very  luminous  objeftstoo  long  a  time. 

IX.  A  quantity  of Jlimulus  greater  than  the  preceding  induces  a  tem- 
porary paralyfis  of  the  organ  of  vi/ion. 

1.  PLACE  a  circular  piece  of  bright  red  filk,  about  half  an  inch 
in  diameter,  on  the  middle  of  a  fhset  of  white  paper  •,  lay  them 
on  the  floor  in    a  bright  funfhine,  and  fixing  your  eyes  ileadily 
on  the  centre  of  the  red  circle,  for  three  or  four  minutes,  at  the 
diftance  of  four  or  fix  feet  from  the  objedt,  the  red  filk  will  grad- 
ually become  paler,  and  finally  ceafe  to  appear  red  at  all. 

2.  Similar  to  thefe  are  many  other  animal  fafts  ;  as  purges, 
opiates,  and  even  poiibns,  and  contagious  matter,  ceafe  to  ftim- 
ulate  our  fyftem,  after  we  have  been  habituated  to  their  ufe.    So 
fome  people    lleep  undifturbed  by  a  clock,  or  even  by  a  forge 
hammer  in  their  neighbourhood  :   and  not  only  continued  irrita- 
tions, but  violent  exertions  of  any  kind,  are  fucceeded  by  tempo- 
rary paralyfis.     The    arm  drops  down  after  violent  aclion,  and 
continues  for  a  time  ufelefs  ;  and  it  is  probable,  that  thofe  who 
have   periihed  fuddenly  in  fwimming,  or  in  fcating  on  the  ice, 
have    owed  their  deaths  to  the  paralyfis,  or  extreme  fatigue, 
which  fucceeds  every  violent  and  continued  exertion. 

X.  MISCELLANEOUS  REMARKS. 

THERE  were  fome  circumftances  occurred  in  making  thefe  ex- 
periments, which  were  liable  to  alter  the  refults  of  them,  and 
which  I  (hall  here  mention  for  the  affitiance  of  others,  who  may 
wifh  to  repeat  them. 

I.  Of  dire  ft  and  inverfe  fpeclra  exijling  at  the  fame  time  ;  of  recipro- 
cal direft  fpeftra  ;  of  a  combination  of  dire  El  and  inverfe  fpeclra  ; 
of  a  fpeclral  halo  ;  rules  to  pre- determine  the  colours  oj  fpeclra. 

a.  When  an  area,  about  fix  inches  fquare,  of  bright  pink  In- 
dian paper,  had  been  viewed  on  an  area,  about  a  foot  fquare,  of 
white  writing  paper,  the  internal  fpeclrum  in  the  clofed  eye  was 
green,  being  the  reverie  fpe&rum  of  the  pink  paper  ;  and  the 
external  fpeclrum  was  pink,  being  the  direft  fpeftrum  of  the 
pink  paper.  The  fame  circumftance  happened  when  the  inter- 
nal area  was  white  and  external  one  pink  ;  that  is,  the  internal 
fpeclrum  was  pink,  and  the  external  one  green.  Ail  the  fame 
appearances  oc  cured  when  the  pink  paper  was  laid  on  a  black 
hat. 

b.  When 


SECT.  XL.  10.  i.    OCULAR  SPECTRA.  457 

b.  When  fix  inches  fquare  of  deep  violet  poliflied  paper  were 
viewed  on  a  foot  fquare  of   white  writing  paper,    the   internal 
fpectrum  was  yellow,  being  the  reverfe   fpectrum  of  the  violet 
paper,  and  the  external  one  was  violet,  being  the   direct  fpeo 
trum  of  the  violet  paper. 

c.  When  fix  inches  fquare  of   pink  paper  were  viewed  on  a 
foot  fquare  of  blue  paper,  the  internal  fpeftrum   was  blue,  and 
the  external  fpe£trum  was  pink  \  that  is,  the  internal  one  was 
a  direct  fpedtrum  of  the  external  object,    and  the  external  one 
was  the  direct  fpedtrum  of  the  internal  object,  inltead  of  their 
being  each  the  reverfe  fpedtrum  of  the  objects  they  belong- 
ed to. 

d.  When  fix  inches  fquare  of  blue  paper  were  viwed    on  a 
foot  fquare  of  yellow  paper,  the  interior  fpectrum  became  a  bril- 
liant yellow,  and  the  exterior  one  a  brilliant  blue.     The  vivaci- 
ty of  the  fpedtra  was  owing  to  their  being  excited  both  by  the 
ftimulus  of  the  interior  and  exterior  objects  ;  fo  that  the  interi- 
or yellow  fpedtrum  was  both  the  reverfe   fpectrum  of  the  blue 
paper,  and  the  direct  one  of  the  yellow  paper  ;  and  the  exterior 
blue  fpectrum  was  both  the  reverfe  fpedlrum  of  the  yellow  pa- 
yer, and  the  direct  one  of  the  blue  paper. 

e.  When  the  internal  area  was  only  a  fquare  half-inch  of  red 
,paper,   laid  on  a  fquare  foot  of  dark  violet  paper,    the  internal 
fpedtrum  was  green,  with  a  reddifh-blue  halo.     When  the  red 
internal  paper  was  two  inches  fquare,  the    internal   fpedtrum 
was  a  deeper  green,  and  the  external  one  redder.       When    the 
internal  paper  was  fix  inches  fquare,  the  fpectrum  of  it  became 
blue,  and  the  fpectrum  of  the  external  paper  was  red. 

f.  When  a  fquare  half  inch  of  blue  paper  was  laid  on   a  fix- 
inch  fquare  of  yellow  paper,   the  fpectrum  of  the  central  pap  r 
in  the  clofed  eye  was  yellow,  incircled  with  a  blue  halo.     On 
looking  long  on  the  meridian  fun,  the  difk  fades  in,to  a  pale  blue 
furrounded  with  a  whitifii  halo. 

Thefe  circumftances,  though  they  very  much  perplexed  the 
experiments  till  they  were  inveftigated,  admit  of  a  fatisfactory 
explanation  ;  for  while  the  rays  from  the  bright  internal  object 
in  exp.  a.  fall  with  their  full  force  on  the  centre  of  the  retina, 
and,  by  fatiguing  that  part  of  it,  induce  the  reverfe  fpectrum, 
many  fcattered  rays,  from  the  fame  internal  pink  paper,  fall  on 
the  more  external  parts  of  the  retina,  but  not  in  fuch  quantity 
as  to  occafion  much  fatigue,  and  hence  induce  the  direct  fpec- 
rrum  of  the  pink  colour  in  thoi'e  parts  of  the  eye.  The  fame  re- 
verfe and  direct  fpectra  occur  from  the  violet  paper  in  exp.  b.  : 
and  in  exp..£.  the  fcattered  rays  from  the  central  pink  paper 
produce  a  direct  fpectrum  of  this  colour  on  the  external  parts 
"  VOL.  I.  Lx  1  of 


OCULAR  SPECTRA.      SECT.  XL.  10.  x. 

of  the  eye,  while  the  (battered  rays  from  the  external  blue  paper 
produce  a  direct  fpeftrum  of  that  colour  on  the  central  part  of 
the  eye,  mftead  of  thefe  parts  of  the  retina  falling  reciprocally 
into  their  reverfe  fpe£lra.  In  exp.  d.  the  colours  being  the  re- 
verfe  of  each  other,  the  fcattered  rays  from  the  exterior  object 
falling  on  the  central  parts  of  the  eye,  and  there  exciting  their 
direol  fpe&rum,  at  the  fame  time  that  the  retina  was  excited  in- 
to a  reverfe  fpedtrum  by  the  central  objeft,  and  this  direct  and 
reverfe  fpectrum  being  of  fimilar  colour,  the  fuperior  brilliancy 
of  this  fpeftrum  was  produced.  In  exp.  e.  the  effect  of  various 
quantities  of  ftimulus  on  the  retina,  from  the  different  refpec- 
tive  fizes  of  the  internal  and  external  areas,  induced  a  fpectrum 
of  the  internal  area  in  the  centre  of  the  eye,  combined  of  the 
reverfe  fpectrum  of  that  internal  area  and  the  direct  one  of  the 
excernal  area,  in  various  (hades  of  colour,  from  a  pale  green  to 
a  deep  blue,  with  fimilar  changes  in  the  ipeftrum  of  the  exter- 
nal area.  For  the  fame  reafons,  when  an  internal  bright  object 
was  fmall,  as  in  exp  /.  mftead  of  the  whole  of  the  fpectrum  of 
the  external  objeft  being  reverfe  to  the  colour  of  the  internal 
object,  only  a  kind  of  halo,  or  radiation  of  colour,  fimila>  to 
that  of  the  internal  object,  was  fpread  a  little  way  on  the  exter- 
nal fpectrum  For  this  internal  blue  area  being  fo  fmall,  the 
fcattered  rays  from  it  extended  but  a  little  way  on  the  image  of 
the  external  area  of  yellow  paper,  and  could  therefore  produce 
only  a  blue  halo  round  the  yellow  fpectrum  in  the  centre. 

If  any  one  (hould  fufpect  that  the  fcattered  rays  from  the  ex- 
terior coloured  objeft  do  not  intermix  with  the  rays  from  the 
interior  coloured  object,  and  thus  affect  the  central  part  of  the 
eye,  let  him  look  through  an  opaque  tube,  about  two  feet  in 
length,  and  an  inch  in  diameter,  at  a  coloured  wall  of  a  room 
with  one  eye,  and  with  the  other  eye  naked  ;  and  he  will  find 
that  by  (hutting  out  the  lateral  light,  the  area  of  the  wall  feen 
through  a  tube  appears  as  if  illuminated  by  the  funfhine,  com- 
pared with  the  other  parts  of  it  ;  from  whence  arifes  the  ad- 
vantage of  looking  through  a  dark  tube  at  diftant  paintings. 

Hence  we  may  fafely  deduce  the  following  rules  to  deter- 
mine before-hand  the  colours  of  all  fpectra.  i.  The  direct 
fpectrum  without  any  lateral  light  is  an  evanefcent  reprefenta- 
tion  of  its  object  in  the  unfatigued  eye.  2.  With  fome  lateral 
light  it  becomes  of  a  colour  combined  of  the  direct  fpectrum 
of  the  central  object,  and  of  the  circumjacent  objects,  in  pro- 
portion to  their  refpective  quantity  and  brilliancy.  3.  The  re- 
verfe fpeclrum  without  lateral  light  is  a  reprefentation  in  the 
fatigued  eye  of  the  form  of  its  objefts,  with  filch  a  colour  as 
would  be  produced  by  all  the  primary  colours,  except  that  of  the 

object* 


SECT.  XL.  10.  2.      OCULAR  SPECTRA.  4jr; 

object.  4.  With  lateral  light  the  colour  is  compounded  of  the 
reverfe  fpe&rum  of  the  central  object,  and  the  direct  fpedrum 
of  the  circumjacent  objects,  in  proportion  to  their  reipeftive 
quantity  and  brilliancy. 

2.   Variation  and  vivacity  of  the  fpeclra  occaftoned   by  extraneous 

light. 

The  reverfe  fpeftrum,  as  has  been  before  explained,  is  fimi- 
lar  to  a  colour,  formed  by  a  combination  or  all  the  primary 
colours,  except  that  with  which  the  eye  has  been  fatigued  in 
making  the  experiment ;  fo  the  reverfe  fpeclrum  of  red  is  fuch 
a  green  as  would  be  produced  by  a  combination  of  all  the  other 
prifmatic  colours.  Now  it  muit  be  obferved,  that  this  reverfe 
fpeclrum  of  red  is  therefore  the  direct  fpeclrum  of  a  combina- 
tion  of  all  the  other  prifmatic  colours,  except  the  red  ;  whence 
on  removing  the  eye  from  a  piece  of  red  (ilk  to  a  fheet  of  white 
paper,  the  green  fpeftrum  which  is  perceived,  may  either  be 
called  the  reverfe  fpe&rum  of  the  red  fiik,  or  the  direct  fpec- 
trum  of  all  the  rays  from  the  white  paper,  except  the  red  ;  for 
in  truth  it  is  both.  Hence  we  fee  the  reafon  why  it  is  not  eafy 
to  gain  a  direct  fpedlrum  of  any  coloured  object  in  the  day- 
time, where  there  is  much  lateral  light,  except  of  very  bright 
objects,  as  of  the  fetting  fun,  or  by  looking  through  an  opaque 
tube ;  becaiife  the  lateral  external  light  falling  alfo  on  the  cen- 
tral part  of  the  retina,  contributes  to  induce  the  reverfe  fpec- 
trum,  which  is  at  the  fame  time  the  direct  fpeftrum  of  that  lat- 
eral light,  deducting  only  the  colour  of  the  central  object  which 
we  have  been  viewing.  And  for  the  fame  reafon,  it  is  difficult 
to  gain  the  reverfe  fpectrum,  where  there  is  no  lateral  light  to 
contribute  to  its  formation.  Thus*  in  looking  through  an  opaque 
tube  on  a  yellow  wall,  and  clofing  my  eye,  without  admitting 
any  lateral  light,  the  fpectra  were  all  at  firft  yellow ;  but  at 
length  changed  into  blue.  And  on  looking  in  the  fame  man- 
ner on  red  paper,  I  did  at  length  get  a  green  fpectrum  ;  but 
they  were  all  at  firft  red  ones :  and  the  fame  after  looking  at  a 
candle  in  the  night. 

The  reverfe  fpectrum  was  formed  with  greater  facility  when 
the  eye  was  thrown  from  the  object  on  a  fheet  of  white  paper, 
or  when  Lght  was  admitted  through  the  clofed  eyelids  ;  becaufe 
not  only  the  fatigued  part  of  the  retina  was  inclined  fpontane- 
oufly  to  fall  into  motions  of  a  contrary  direction  ;  but  being 
ftill  fcnfible  to  all  other  rays  of  light  except  that  with  which  it 
was  lately  fatigued,  was  by  thefe  rays  ftimulated  at  the  fame 
time  into  thofe  motions  which  form  the  reverfe  fpectrum* 

Hence, 


4<5o  OCULAR  SPECTRA.      SECT.  XL,  10.  £V 

Hence,  when  the  reverfe  fpectrum  of  any  colour  became  faint, 
ft  was  wonderfully  revived  by  admitting  more  light  through  the 
eyelids,  by  removing  the  hand  from  before  them  :  and  hence, 
on  covering  the  clofed  eyelids,  the  fpectrum  would  often  ceafe 
for  a  time,  till  the  retina  became  fenfible  to  the  flimulus  of  the 
fmaller  quantity  of  light,  and  then  it  recurred.  Nor  was  the 
fpectrum  only  changed  in  vivacity,  or  in  degree,  by  this  admif. 
fion  of  light  through  the  eyelids  ;  but  it  frequently  happened, 
after  having  >:  viewed  bright  objects,  that  the  fpectrum  in  the 
clofed  and  covered  eye  was  changed  into  a  third  fpectrum,  when 
light  was  admitted  through  the  eyelids  :  which  third  fpectrum 
was  compofed  of  fuch  colours  as  could  pafs  through  the  eyelids* 
except  thoie  of  the  object.  Thus,  when  an  area  of  half  an  inch 
diameter  of  pink  paper  was  viewed  on  a  meet  of  white  paper  in 
the  funmine,  the  fpectrum  with  clofed  and  covered  eyes  was 
green ;  but  on  removing  the  hands  from  before  the  clofed  eye- 
lids, the  fpectrum  became  yellow,  and  returned  inftantly  again 
to  green,  as  often  as  the  hands  were  applied  to  cover  the  eye- 
lids, or  removed  from  them  :  for  the  retina  being  now  infenfible 
to  red  light,  the  yellow  rays  palling  through  the  eyelids  in  great- 
er quantity  than  the  other  colours,  induced  a  yellow  fpectrum  ; 
whereas  if  the  fpectrum  was  thrown  on  white  paper,  with  the 
eyes  open  it  became  only  a  lighter  green. 

Though  a  certain  quantity  of  light  facilitates  the  formation  of 
the  reverfe  fpectrum,  a  greater  quantity  prevents  its  formation, 
as  the  more  powerful  ftimulus  excites  even  the  fatigued  parts  of 
the  eye  into  action;  otherwife  we  fhould  fee  the  fpectrum  of 
the  iaft  viewed  object  as  often  as  we  turn  our  eyes,  Hence 
the  reverfe  fpectra  are  bed  feen  by  gradually  approaching  the 
hand  near  the  clofed  eyelids  to  a  certain  diftance  only,  which 
mult  be  varied  with  the  brightnefs  of  the  day,  or  the  energy  of 
the  fpectrum.  Add  to  this,  that  all  dark  fpectra,  as  black,  blue, 
or  green,  if  light  be  admitted  through  the  eye;ids  after  they 
have  been  fome  time  covered,  give  reddiih  fpectra,  for  the  rea- 
fons  given  in  beet,  III.  Exp  i. 

From  thefe  circumftances  of  the  extraneous  light  coinciding 
with  the  fpontaneous  efforts  of  the  fatigued  retina  to  produce  a 
reverfe  fpectrum,  as  was  obferved  before,  it  is  not  eafy  to  gain 
a  direct  fpectrum,  except  of  objects  brighter  than  the  ambient 
light ;  fuch  as  a  candle  in  tlie  night,  the  fetting  fun,  or  viewing 
a  bright  object  through  an  opaque  tube  ;  and  then  the  reverfe 
fpectrum  is  inilantaneoufly  produced  by  the  admiflion  of  ibme 
external  light  ;  and  is  as  inftantly  converted  again  to  the  direct 
fpectrum  by  the  exclufion  of  it-  Thus,  on  looking  at  the  fet* 
ting  fun  i  on  doling  the  eyes,  and  covering  them,  a  yellow  fpec- 
trum 


SECT.  XL.  10.  3.      OCULAR  SPECTRA*  461 

trum  is  feen,  which  is  the  direct  fpe&rum  of  the  fetting  fun  ; 
but  on  opening  the  eyes  on  the  iky,  the  yellow  fpe&rum  is  im- 
mediately changed  into  a  blue  one,  which  is  the  reverfe  fpec- 
trum  of  the  yellow  fun,  or  the  direct  fpeftrum  of  the  blue  fky, 
or  a  combination  of  both.  And  this  is  again  transformed  into 
a  yellow  one  on  clofing  the  eyes,  and  fo  reciprocally,  as  quick 
as  the  motions  of  the  opening  and  clofing  eyelids.  Hence, 
when  Mr.  Melvill  obierved  the  fcintillations  of  the  ftar  Sirius  to 
be  ibmetimes  coloured,  thefe  were  probably  the  direct  fpeclrum 
of  the  blue  iky  on  the  parts  of  the  retina  fatigued  by  the  white 
light  of  the  (tar.  [Eflays  Phyfical  and  Literary,  p.  81.  V.  2.] 

When  a  direct  fpeclrum  is  thrown  on  colours  darker  than 
itfelf,  it  mixes  with  them  ;  as  the  yellow  fpeclrum  of  the  fet- 
ting lun,  thrown  on  the  green  grafs,  becomes  a  ^greener  yellow. 
But  when  a  direct  fpeclrum  is  thrown  on  colours  brighter  than 
itielf,  it  becomes  inftantly  changed  into  the  reverfe  fpeftrum, 
which  mixes  with  thoie  brighter  colours.  So  the  yellow  fpec- 
trum  of  the  fetting  fun  thrown  on  the  luminous  fky  becomes 
blue,  and  changes  with  the  colour  or  brightnefs  of  the  clouds 
on  which  it  appears.  But  the  reverfe  fpeclrum  mixes  with  ev- 
ery kind  of  colour  on  which  it  is  thrown,  whether  brighter  than 
itfeif  or  not :  thus  the  reverfe  fpectrum,  obtained  by  viewing  a 
piece  of  yellow  filk,  when  thrown  on  white  paper,  was  a  lucid 
blue  green  ;  when  thrown  on  black  Turkey  leather,  becomes  a 
deep  violet.  And  the  fpeclrum  of  blue  filk,  thrown  on  white 
paper,  was  a  light  yellow  ;  on  black  filk  was  an  obfcure  orange ; 
and  the  blue  fpeclrum,  obtained  from  orange-coloured  filk, 
thrown  on  yellow,  became  a  green. 

In  thefe  cafes  the  retina  is  thrown  into  activity  or  fenfation 
by  the  itimulus  of  external  colours,  at  the  fame  time  that  it  con- 
tinues the  activity  or  fenfation  which  forms  the  fpeclra  ;  in  the 
fame  manner  as  the  prifmatic  colours,  painted  on  a  whirling 
top,  are  feen  to  mix  together.  When  thefe  colours  of  external 
objects  are  brighter  than  the  direct  fpectrum  which  is  thrown 
upon  them,  they  change  it  into  the  reverfe  fpeclrum,  like  the 
admiilion  of  external  light  on  a  direct  fpectrum,  as  explained 
above.  When  they  are  darker  than  the  direct  fpeclrum,  they 
mix  it,  their  weaker  ftimuius  being  inefficient  to  induce  the  re- 
verfe fpeclrum. 

3.   Variation  oj  fyeftr a  in  refpeft  to  number ',  and  figure y  and  re- 

miffion. 

When  we  Jook  long  and  attentively  at  any  object,  the  eye  can- 
not always  be  kept  entirely  motionlefs  \  hence,  on  infpecling  a 

circular 


462  OCULAR  SPECTRA.      SECT.  XL.  10.  3. 

circular  area  of  red  filk  placed  on  white  paper,  a  lucid  crefcent 
or  edge  is  feen  to  librate  on  one  fide  or  other  of  the  red  circle  : 
for  the  exterior  parts  of  the  retina  fometimes  falling  on  the  edge 
of  the  central  filk,  and  fometimes  on  the  white  paper,  are  lefs 
fatigued  with  red  1'ght  than  the  central  part  of  the  retina,  which 
is  conftantly  expofed  to  it ;  and  therefore,  when  they  fall  on  the 
edge  of  the  red  filk,  they  perceive  it  more  vividly.  Afterwards, 
when  the  eye  becomes  fatigued,  a  green  fpe&rum  in  the  form 
of  a  crefcent  is  ieen  to  librate  on  one  fide  or  other  of  the  central 
circle,  as  by  the  uniteadinefs  of  the  eye  a  part  of  the  fatigued 
retina  falls  on  the  white  paper  ;  and  as  by  the  increafing  fatigue 
of  the  eye  the  central  part  of  the  filk  appears  paler,  the  edge  on 
which  the  unfatigued  part  of  the  retina  occafionally  falls  will  ap- 
pear of  a  deeper  red  than  the  original  filk,  becaufe  it  is  com- 
pared with  the  pale  internal  part  of  it.  M  de  Buffbn  in  mak- 
ing this  experiment  observed,  that  the  red  edge  of  the  filk  was 
not  only  deeper  coloured  than  the  original  filk  ;  but,  on  his  re- 
treating a  little  from  it,  it  became  oblong,  and  at  length  divided 
into  two,  which  mult  have  been  owing  to  his  obferving  it  either 
before  or  behind  the  point  of  interfe£lion  of  the  two  optic  ax- 
ifes.  Thus,  if  a  pen  is  held  up  before  a  diftant  candle,  when 
we  look  interifely  at  the  pen  two  candles  are  feen  behind  it ; 
when  we  look  intenfely  at  the  candle  two  pens  are  feen.  If 
the  fight  be  unlteady  at  the  time  of  beholding  the  fun,  even 
though  one  eye  only  be  ufed,  many  images  of  the  fun  will  ap- 
pear, or  luminous  lines,  when  the  eye  is  clofed.  And  as  fome 
parts  of  thefe  will  be  more  vivid  than  others,  and  fome  parts  of 
them  will  be  produced  nearer  the  centre  of  the  eye  than  others, 
thefe  will  difappear  fooner  than  the  others ;  and  hence  the  num- 
ber and  fhape  of  thefe  fpeftra  of  the  fun  will  continually  vary, 
as  long  as  they  exiit.  The  caufe  of  fome  being  more  vivid  than 
others,  is  the  unfteadinefs  of  the  eye  of  the  beholder,  fo  that 
fome  parts  of  the  retina  have  been  longer  expofed  to  the  fun- 
beams.  That  fome  parts  of  a  complicated  fpedlrum  fade  and 
return  before  other  parts  of  it,  the  following  experiment  evinces. 
Draw  three  concentric  circles  ;  the  external  one  an  inch  and  a 
half  in  diameter,  the  middle  one  an  inch,  and  the  internal  one 
half  an  inch  ;  colour  the  external  and  internal  areas  blue,  and 
the  remaining  one  yellow,  as  in  Fig.  4  ;  after  having  looked 
about  a  minwe  on  the  centre  of  thefe  circles,  in  a  bright  light, 
the  fpeftrum  of  the  external  area  appears  firft  in  the  clofed  eye, 
then  the  middle  area,  and  laftly  the  central  one;  and  then  the 
central  one  difappea*  s,  and  the  others  in  inverted  order.  If  con- 
centric circles  o^  o  ore  colours  are  added,  it  produces  the  beau- 
tiful ever  changing  fpe&rum  in  Sed.  I.  Exp.  a. 

From 


SECT.  XL.  10. 4.         OCULAR  SPECTRA.  46.3 

From  hence  it  would  feem,  that  the  centre  of  the  eye  produ- 
ces quicker  remiflions  of  fpe&ra,  owing  perhaps  to  its  greater 
fenfibility  ;  that  is  to  its  more  energetic  exertions.  Thefe  re- 
miflions  of  fpeclra  bear  fome  analogy  to  the  tremors  of  the 
hands*  and  palpitations  of  the  heart,  of  weak  people  :  and  per- 
haps a  criterion  of  the  ftrength  of  any  mufcle  or  nerve  may  be 
taken  from  the  time  it  can  be  continued  in  exertion. 

4,  Variation  offpeclra  in  refpeft  to  brilliancy  ;  the  vijibility  of  the 
circulation  of  the  blood  in  the  eye. 

1.  The  meridian  or  evening  light  makes  a  difference  in  the 
colours  of  fome  fpeftra  ;  for  as  the  fun  defcends,  the  red  rays-, 
which  are  lefs  refrangible  by  the  convex  atmofphere,  abound  in 
great  quantity.     Whence  the  fpeclrum  of  the  light  parts  of  a 
window  at  this  time,  or  early  in  the  morning,  is  red  ;  and  be- 
comes blue  either  a  little  later  or  earlier ;  and  white  in  the  me-* 
ridian  day ;  and  is  alfo  variable  from  the  colour  of  the  clouds 
or  (ky  which  are  oppofed  to  the  window. 

2.  All  thefe  experiments  are  liable  to  be  confounded,  if  they 
are  made  too  foon  after  each  other,  as  the  remaining  fpeftrum 
will  mix  with  the  new  ones.     This    is  a  very  troublefome  cir- 
cumftance  to  painters,  who  are  obliged  to  look  long  upon  the 
fame  colour  ;  and  in  particular  to  thofe  whofe  eyes,  from  natur- 
al debility,  cannot  long  continue  the  fame  kind  of   exertion. 
For  the  fame  reafon,  in  making  thefe  experiments,  the  refult  be- 
comes much  varied  if  the  eyes,  after  viewing  any  object,  are  re- 
moved on  other  objects  but  for  an  inftant  of  time,  before  we 
clofe  them  to  view  the  fpeftrum  ;  for  the  light  from  the  objeft, 
of  which  we  had  only  a  tranfien'  view,  in  the  very  time  of  clo- 
fing  our  eyes  acts  as  a  ftimulus  on  the  fatigued  retina  ;    and  for 
a  time  prevents  the  defired  fpeclrum  from  appearing,  or  mixes 
its  own  fpeclrum  with  it.     Whence,  after  the  eyelids  are  clofed, 
either  a  dark  field,  or  fome  unexpected  colours,  are  beheld  for  a 
fewfeconds,before  the  defired  fpectrum becomes  diftin£Uy  vifible. 

3.  The  length  of   time  taken   up  in  viewing  an  object  of 
which  we  are  to  obferve  the  fpe&rum,  makes  a  great  difference 
in  the  appearance  of  the  fpe&rum,  not  only  in  its  vivacity,   but 
in  its  colour  \  as  the  direct  fpeftrum  of  the  central  object,  or  of 
the  circumjacent  ones,  and  alfo  the  reverfe  fpectra  of  both,  with 
their  various  combinations,  as  well  as  the  time  of  their  duration 
in  the  eye.   and  of  their  remiflions  or  alterations,   depend  upon 
the  degree  of  fatigue  the  retina  is  fubject   to.     The  Chevalier 
d'Arcy  conirrucic-f!  a  machine  by    which  a   coal  of    fire    was 
thirled  'round  in  the  dark,  and  found,  that   when  a  luminous 

body 


464  OCULAR  SPECTRA.      SECT.  XL.  10.  4 

body  made  revolution  in  eight  thirds  of  time,  is  prefented  to  the 
eye  a  complete  circle  of  fire ;  from  whence  he  concludes,  that: 
the  impreflion  continues  on  the  organ  about  the  feventh  part  oi 
a  fecond,  (Mem.  de  TAcad.  des  Sc.  1765.)  This,  however, 
is  only  to  be  confidered  as  the  (horteft  time  of  the  duration  of 
thefe  direcT;  fpe&ral;  fnice  in  the  fatigued  eye  both  the  direct 
and  reverfe  fpeftra,  with  their  intermiflions,  appear  to  take  up 
many  feconds  of  time,  and  feem  very  variable  in  proportion  to 
the  circumilances  of  fatigue  or  energy. 

4.  It  fometimes  happens,  if  the  eyeballs  have  been  rubbed 
haid  with  the  fingers,  that  lucid  fparks  are  feen  in  quick  mo- 
tion amidft  the  fpe&rurn  we  are  attending  to.  This  is  fimilar 
to  the  flames  of  fire  from  a  ftroke  on  the  eye  in  fighting,  and  is 
refembled  by  the  warmth  and  glow,  which  appears  upon  the  fkin 
after  fridtion,  and  is  probably  owing  to  an  acceleration  of  the  ar- 
terial blood  into  the  vefiels  emptied  by  the  previous  preffure.  By 
being  accuftomed  to  obferve  fuch  fmall  fenfations  in  the  eye,  it 
is  eafy  to  fee  the  circulation  of  the  blood  in  this  organ  I  have 
attended  to  this  frequently,  when  I  have  obferved  my  eyes  more 
than  commonly  fenfible  to  other  fpeclra.  The  circulation  may 
be  feen  either  in  both  eyes  at  a  time,  or  only  in  one  of  them  ; 
for  as  a  certain  quantity  of  light  is  neceflary  to  produce  this 
curious  phenomenon,  if  one  hand  be  brought  nearer  the  C!OT 
fed  eyelids  than  the  other,  the  circulation  in  that  eye  will  for  a 
time  difappear.  For  the  eafier  viewing  the  circulation,  it  is 
fometimes  neceflary  to  rub  the  eyes  with  a  certain  degree 
*of  force  after  they  are  clofed,  and  to  hold  the  breath  rather 
longer  than  is  agreeable,  which,  by  accumulating  more  blood 
in  the  eye,  facilitates  the  experiment ;  but  in  general  it  may  be 
feen  diftinftly  after  having  examined  other  fpe£tra  with  your 
back  to  the  light  till  the  eyes  become  weary  ;  then  having  cover- 
ed your  clofed  eyelids  for  half  a  minute,  till  the  fpedrum  is  fa- 
ded away  which  you  were  examining,  turn  your  face  to  the  light, 
and  removing  your  hands  from  the  eyelids,  by  and  by  again 
{hade  them  alittle,  and  the  circulation  becomes  curioufly  diftinft. 
The  ftreams  of  blood  are  however  generally  feen  to  unite, 
which  (hews  it  to  be  the  venous  circulation,  owing,  I  fuppofe, 
to  the  greater  opacity  of  the  colour  of  the  blood  in  thefe  veflels  $ 
for  this  venous  circulation  is  alfo  much  more  eafily  feen  by  the 
microfcope  in  the  tail  of  a  tadpole. 

5 .  Variation  offpeElra  In  refpeEl  to  diflinElnefs  andjlze  /  with  a  peiv 
ivay  of  magnifying  objects. 

I.  It  was  before  obferved,  that  when  the  two  colours  viewed 

together 


466  OCULAR  SPECTRA.        SECT.  XL.  10.  6. 

clofing  my  eyes,  and  (hading  them  fomewhat  with  my  hand, 
the  word  was  di(lin£tly  feen  in  the  fpe£trum  in  yellow  letters 
on  a  blue  field  ;  and  then,  on  opening  my  eyes  on  a  yellowifh 
wall  at  twenty  feet  diftance,  the  magnified  name  of  BANKS 
appeared  written  on  the  wall  in  golden  characters. 

6.  Conclufion. 

IT  was  obferved  by  the  learned  M.  Sauvages  (Nofol.  Method. 
Cl.  VIII.  Ord.  i.)  that  the  pulfations  of  the  optic  artery  might 
be  perceived  by  looking  attentively  on  a  white  wall  well  illumin- 
ated. A  kind  of  net-work,  darker  than  the  other  parts  of  the 
wall,  appears  and  vanifhes  alternately  with  every  pulfation. 
This  change  of  the  colour  of  the  wall  he  well  afcribes  to  the 
cornpreflion  of  the  retina  by  the  diaftole  of  the  artery.  The  va- 
rious colours  produced  in  the  eye  by  the  preflure  of  the  finger, 
or  by  a  ftroke  on  it,  as  mentioned  by  Sir  Ifaac  Newton,  feem 
likewife  to  originate  from  the  unequal  preflure  on  various  parts 
of  the  retina.  Now  as  Sir  Ifaac  Newton  has  fhewn,  that  all 
the  different  colours  are  reflected  or  tranfmitted  by  the  laminae 
of  foap  bubbles,  or  of  air,  according  to  their  different  thicknefs 
or  thinnefs,  is  it  not  probable,  that  the  effedt  of  the  activity  of  the 
retina  may  be  to  alter  its  thicknefs  or  thinnefs,  fo  as  better  to 
adapt  it  to  reflect  or  tranfmit  the  colours  which  ftimulate  it  into 
adtion  ?  May  not  mufcular  fibres  exift  in  the  retina  for  this  pur- 
pofe,  which  may  be  lefs  minute  than  the  locomotive  mufcles  of 
microfcopic  animals  ?  May  not  thefe  mufcular  a£tions  of  the  ret- 
ina conftitute  the  fenfation  of  light  and  colours  ;  and  the  volun- 
tary repetitions  of  them,  when  the  obje£t  is  withdrawn,  confti- 
tute our  memory  to  them  ?  And  laftly,  may  not  the  laws  of  the 
fenfations  of  light,  here  inveftigated,  be  applicable  to  all  our  oth- 
er fenfes,  and  much  contribute  to  elucidate  many  phenomena  of 
animal  bodies  both  in  their  healthy  and  difeafed  ftate  ;  and  thus 
render  this  inveftigation  well  worthy  the  attention  of  the  phyfi 
cian,  the  metaphyfician,  and  the  natural  philofopher  ? 

November  i,  1785. 

Dum,  Liber  !  aftra  petis  volitans  trepidantibus  alis, 

Irruis  immemori,  parvula  gijtta,  mari. 
Me  quoque,  mecurrente  rota  revolubilis  aetas 

Volverit  in  tenebras, — i,  Liber,  ipfe  fequor. 


END  OF  THE  FIRST  PART; 


Z  O  O  N  O  M  I  A  ; 


OR, 


THE  LAWS  OF  ORGANIC  LIFE. 


PART    III. 


CONTAINING 


THE  ARTICLES  OF  THE  MATERIA  MEDICA, 


WITH    AN    ACCOUNT    OF    THE 


OPERATION  OF  MEDICINES. 


IN  VIVUM  CORPUS 
AGUNT    MEDICAMENTA.. 


PREFACE. 


THE  MATERIA  MEDICA  includes  all  thofe  fubftan- 
ces,  which  may  contribute  to  the  rtftoration  of  health. 
Thefe  may  be  conveniently  diitributed  under  leven  ar- 
ticles according  to  the  diverfity  of  their  operations. 

1.  NUTRIENTIA,  or    thofe    things  which  prefcrve 
in  their  natural  (late  the  due  exertions  ol  all  the  irrita- 
tive motions. 

2.  INCITANTIA,  or   thofe  things  which  increafe  the 
exertions  of  all  the  irritative  motions. 

3.  SECERNENTIA,    or   thofe  things  which  increafe 
the  irritative  motions,  which  conftitute  fecretion. 

4.  SORBENTIA,  or    thofe    things  which  increafe  the 
irritative  motions,  which  conftitute  abforption. 

5.  INVERTENTIA,   or  thofe  things  which  invert  the 
natural  order  of  the  fucceflive  irritative  motions. 

6.  REVERTENTIA,   or  thofe    things    which  reftore 
the  natural  order  of  the  inverted  irritative  motions. 

7.  TORPENTIA, 


4  PREFACE. 

7.  TORPENTIA,  thofe  things  which  diminifli  the 
exertions  of  all  the  irritative  motions. 

It  is  neceflary  to  apprize  the  reader,  that  in  the 
following  account  of  the  virtues  of  Medicines  their 
ufual  dofes  are  always  fuppofed  to  be  exhibited ;  and 
the  patient  to  be  expofed  to  the  degree  of  exterior 
heat,  which  he  has  been  accuftomed  to,  (where  the 
contrary  is  not  mentioned),  as  any  variation  of  either  of 
thefe  circumftances  varies  their  effe&s. 


ARTICLES 


OF    THE 


MATERIA  MEDICA, 


ART.  I. 
NUTRIENTIA. 


L  i.  THOSE  THINGS,  which  preferve  in  the  natural  {late  the 
due  exertions  of  all  the  irritative  motions,  are  termed  nutrien- 
tia  ;  they  produce  the  growth,  and  reftore  the  wafte,  of  the  fyf- 
tem.  Thefe  confift  of  a  variety  of  mild  vegetable  and  animal 
fubftances,  water  and  air. 

2.  Where  flronger  ftimuli  have  been  long  ufed,  they  become 
neceflary  for  this  purpofe,  as  muftard,  fpice,  fait,  beer,  wine, 
vinegar,  alcohol,  opium.  Which  however,  as  they  are  unnat- 
ural ftimuli,  and  difficult  to  manage  in  refpett  to  quantity,  are 
liable  to  (horten  the  fpan  of  human  life,  fooner  rendering  the 
fyftem  incapable  of  being  ftimulated  into  aclion  by  the  nutrien- 
tia.  See  Seel.  XXXVII.  4.  On  the  fame  account  life  is  ihort- 
er  in  warmer  climates  than  in  more  temperate  ones. 

II.  OBSERVATIONS  ON  THE  NUTRIENTIA. 

I.  i.  The  flefli  of  animals  contains  more  nourifliment,  and 
ftimulates  our  abforbent  and  fecerning  veflels  more  powerfully, 
than  the  vegetable  productions,  which  we  ufe  as  food  ;  for  the 
carnivorous  animals  can  faft  longer  without  injury  than  the 
graminivorous  ;  and  we  feel  ourfelves  warmer  and  ftronger  af- 
ter a  meal  of  flefti  than  of  grain.  Hence  in  difeafes  attended  with 
cold  extremities  and  general  debility  this  kind  of  diet  is  prefer- 
red; as  in  rickets,  dropfy,  fcrofula,  and  in  hyfteric  and  hypochon- 
driac cafes,  and  to  prevent  the  returns  of  agues.  Might  not 

flefli 


6  NUTRIENTIA.  ART.  I.  2.  i.  2. 

flefli  in  fmall  quantities  bruifed  to  a  pulp  be  more  ad  vantage  ouf- 
ly  ufed  in  fevers  attended  with  debility  than  vegetable  diet  ? 

That  fleftu  which  is  of  the  darkeft  colour,  generally  contains 
more  nourifhrnent,  and  (limulates  our  veiTels  more  powerfully, 
than  the  white  kinds.  The  flefh  of  the  carnivorous  and  pifciv- 
orous  animals  is  fo  ftimulating,  that  it  feldom  enters  into  the 
food  of  European  nations,  except  the  fwine,  the  Soland  goofe 
(Pelicanus  Baflanus),  and  formerly  the  fwan.  Of  thefe  the 
fwinf  and  the  fwan  are  fed  previoufly  upon  vegetable  aliment ; 
and  the  Soland  goofe  is  taken  in  very  fmall  quantity,  only  as  a 
whet  to  the  appetite.  Next  to  thefe  are  the  birds,  that  feed  up- 
on infects,  which  are  perhaps  the  moil  (limulating  and  the  moil 
nutritive  of  our  ufual  food. 

It  is  faid  that  a  greater  quantity  of  volatile  alkali  can  be  ob- 
tained from  this  kind  of  flefh,  to  which  ha^.  been  afcribed  its 
ftimulating  quality  But  it  is  more  probable,  that  frefh  flefli 
contains  only  the  elements  of  volatile  alkali. 

2.  Next  to  the  dark  coloured  flefh  of  animals,  the  various  tribes 
of  fhell-fifh  feem  to  claim  their  place,  and  the  wholefome  kinds 
of  mufhrooms,  which  mull  be  efteemed  animal  food,  both  for 
their  alkalefcent  tendency,  their  ftimulating  quality,  and  the 
quantity  of  nourifhment,  which  they  afford;  as  oyiters,  lobfters, 
crab-fifh,  fhrimps  ;  mufhrooms  ;  to  which  perhaps  might  be 
added  fome  of  the  fifh  without  fcales  ;  as  the  eel,  barbolt,  tench, 
fmelt,  turbot,  turtle. 

The  fiefh  of  many  kinds  of  flfh,  when  it  is  fuppofed  to  have 
undergone  a  beginning  putrefaction,  becomes  luminous  in  the 
dark.  This  feems  to  (hew  a  tendency  in  the  phofphorus  to  ef- 
cape,  and  combine  with  the  oxygen  of  the  atrnofphere  ^  and 
would  hence  fhew,  that  this  kind  of  flefh  is  not  fo  perfectly  an- 
imaJized  as  thofe  before  mentioned-  This  light,  as  it  is  fre- 
quently feenonronen  wood,  and  fometimes  on  veal,  which  has 
been  kept  too  long,  as  I  have  been  told,  is  commonly  fuppofed 
to  have  its  caufe  from  putrefaction ;  but  is  neverthelefs  moft 
probably  of  phofphoric  origin,  like  that  feen  in  the  dark  on 
oyfter-mells,  which  have  previoufly  been  ignited  and  afterwards 
expofec!  to  the  funfhine,  and  on  the  Bolognian  ftone.  See  Bo- 
tan.  Card.  Vol.  I.  Cant.  I.  line  182,  the  note,  and  additional 
note  X. 

3  I  he  flefh  of  young  animals,  as  of  lamb,  veal,  and  fucking- 
pigs,  fupplies  us  with  a  flill  lefs  Simulating  food  The  broth 
of  thefe  is  faid  to  become  four,  an  1  continues  fo  a  confiderable 
time  before  it  changes  into  putridity  ;  fo  much  loes  their  flelh 
partake  of  the  chemical  properties  of  the  milk,  with  which  thefe 
animals  are  nourifhed. 

4.  The 


ART.  I.  1.4.  2.  NUTRIENTIA.  7 

4.  The  white  meats,  as  of  turkey,  partridge,  pheafant,  fowl, 
with  their  eggs,  feem  to  be  the  next  in  mildnefs  ;  and  hence  are 
generally  firft  allowed  to  convalefcents  from  inflammatory  dif- 
eafes, 

5  Next  to  thofe  mould  be  ranked  the  white  river-filh,  which 
have  fcales,  as  pike,  perch,  gudgeon. 

II  r .  Milk  unites  the  animal  with  the  vegetable  fource  of  our 
nourifhment,  partaking  of  the  properties  of  both.  As  it  con- 
tains fugar,  and  will  therefore  ferment  and  produce  a  kind  of 
wine  or  fpirit,  which  is  a  common  liquor  in  Siberia  ;  or  will  run 
into  an  acid  by  fnnple  agitation,  as  in  the  churning  of  cream  ; 
and  laftly,  as  it  contains  coagulable  lymph,  which  will  undergo 
the  procefs  of  putrefaction  like  other  animal  fubftances,  as  in  old 
cheefe. 

2.  Milk  may  be  feparated  by  reft  or  by  agitation,  into  cream, 
butter,  butter-milk,  whey,  curd.  The  cream  is  eafier  of  digeition 
to  adults,  becaufe  it  contains  lefs  of  the  coagulum  or  cheefy  parr, 
and  is  alfo  more  nutritive.  Butter  confiding  of  oil  between  an 
animal  and  vegetable  kind  contains  ftill  more  nutriment,  and  in 
its  recent  ftate  is  not  difficult  of  digeftion  if  taken  in  moderate 
quantity.  See  Art.  I.  2.  3.  2.  Buttermilk  if  it  be  not  bitter  is 
an  agreeable  and  nutritive  fluid  ;  if  it  be  bitter  it  has  fome  pu- 
trid parts  of  the  cream  in  it,  which  had  been  kept  too  long  ; 
but  is  perhaps  not  lefs  wholefome  for  being  four  to  a  certain 
degree  :  as  the  inferior  people  in  Scotland  choofe  four  milk  in 
preference  to  (kirnmed  milk  before  it  is  become  four.  Whey  is 
the  lealt  nutritive  and  eafieft  of  digeftion.  And  in  the  fpring 
of  the  year,  when  the  cows  feed  on  young  grafs,  it  contains  fa 
much  of  vegetable  properties,  as  to  become  a  falutary  potation, 
when  drunk  to  about  a  pint  every  morning,  to  thofe  who  du- 
ring the  winter  have  taken  too  little  vegetable  nouriihment,  and 
who  are  thence  liable  to  bilious  concretions. 

3  Cheefe  is  of  various  kinds,  according  to  the  greater  or  lefs 
quantity  of  cream,  which  it  contains,  and  according  to  its  age. 
Thofe  cheefes,  which  are  eaiieft  broken  to  pieces  in  the  mouth, 
are  generally  eafieft  of  digeftion,  and  contain  moft  nutriment. 
Some  kinds  of  cheefe,  though  ilow  of  digeftion,  are  alfo  flow  in 
changing  by  chemical  proceiTes  in  the  ftomach,  and  therefore 
will  frequently  agree  well  with  thofe,  who  have  a  weak  digeftion ; 
as  I  have  feen  toafted  cheefe  vomited  up  a  whole  clay  after  it 
was  eaten  without  having  undergone  any  apparent  change,  or 
give.n  any  uneafmefs  to  the  patient.  It  is  probable  a  portion  of 
fugar,  or  of  animal  fat,  or  of  the  gravy  of  boiled  or  roafted  meat, 
mixed  with  cheefe  at  the  time  of  making  it,  might  add  to  its 
pleafant  and  nutritious  quality. 

VOL.  I,  N  N  n  4.  The 


8  NUTRIENTIA.  ART.  I.  2. 2. 4. 

,4.  The  rcafon  why  autumnal  milk  is  fo  much  thicker  or  co- 
agulable  than  vernal  milk,  is  not  uneafy  to  underftand  ;  but  asnew 
milk  is  in  many  refpefls  fimilar  to  chyle,  it  may  be  confidered 
as  food  already  in  part  digefted  by  the  animal  it  is  taken  from, 
and  thence  fupplies  a  nutriment  of  eafy  digeftion.  As  it  requires 
to  be  curdled  by  the  gaftric  acid,  before  it  can  enter  the  lac- 
teals,  as  is  feen  in  the  ftomachs  of  calves,  it  feems  more  fuita- 
ble  to  children,  whofe  ftomachs  abound  more  with  acidity,  than 
to  adults ;  but  neverthelefs  fupplies  good  nourifliment  to  many 
of  the  latter,  and  particularly  to  thofe,  who  ufe  vegetable  food, 
and  whofe  ftomachs  have  not  been  much  accuftomed  to  the  un- 
natural ftimulus  of  fpice,  fait,  and  fpirit.  See  Clais  I.  I.  2.  5. 

III.  i*  The  feeds,  roots,  leaves,  and  fruits  of  plants,  confti- 
tute  the  greateft  part  of  the  food  of  mankind  j  the  refpecSHve 
quantities  of  nouriftiment  which  thefe  contain,  may  perhaps  be 
eftimated  from  the  quantity  of  ftarch,  or  of  fugar,  they  can  be 
made  to  produce  :  in  farinaceous  feeds,  the  mucilage  feems  grad- 
ually to  be  converted  into  ftarch,  while  they  remain  in  our  gra- 
naries *,  and  the  ftarch  by  the  germination  of  the  young  plant, 
as  in  making  malt  from  barley,  or  by  animal  digeftion,  is 
converted  into  fugar.  Hence  old  wheat  and  beans  contain 
more  ftarch  than  new  ;  and  in  our  ftomachs  other  vegetable  and 
animal  materials  are  converted  into  fugar  ;  which  conftitutes  in 
all  creatures  a  part  of  their  chyle. 

Hence  it  is  probable,  that  fugar  is  the  moft  nutritive  part  of 
vegetables  *,  and  that  they  are  more  nutritive,  as  they  are  con- 
vertible in  greater  quantity  into  fugar  by  the  power  of  digeftion  ; 
as  appears  from  fugar  being  found  in  the  chyle  of  all  animals, 
and  from  its  exifting  in  great  quantity  in  the  urine  of  patients 
in  the  diabetes,  of  which  a  curious  cafe  is  related  in  Seft.  XXIX. 
4.  where  a  man  labouring  under  this  malady  ate  and  drank  an 
enormous  quantity,  and  fometimes  voided  fixteen  pints  of  water 
in  a  day,  with  an  ounce  of  fugar  in  each  pint. 

The  nutritive  quality  of  fugar  is  not  only  (hewn  by  the  flaves 
in  Jamaica,  and  other  animals,  becoming  fatter  in  the  fugar 
harveft,  though  they  are  forced  to  labour  more,  but  alfo  from 
the  many  inftances  of  its  nourifhing  for  fome  years  very  old 
people,  who  could  take  little  of  any  other  food.  Many  of 
which  cafes  are  recorded  in  Dr.  Mofely's  Treatife  on  Sugar, 
and  three  I  have  myfelf  witnefled. 

Nor  is  this  to  be  wondered  at,  as  it  conftitutes  a  part  of  the 
chyle  both  of  vegetables  and  animals  ;  which  only  feem  to  dif- 
fer from  each  other  in  this  circumftance,  that  the  chyle  of  veg- 
etables confifts  principally  of  fugar  and  mucilage  diflblved  in 
water  j  as  the  juice  extracted  from  birch  and  maple-trees  in 

the 


ART.  I.  2. 3. 2.  NUTRIENTIA.  9 

the  vernal  months,  and  is  therefore  tranfparent  and  colourlefs  -, 
but  the  chyle  of  animals  alfo  contains  oil,  mixed  with  the  fugar 
and  mucilage  and  water,  which  gives  its  milky  appearance, 
owing  to  its  imperfect  folution. 

2.  Oil,  when  mixed  with  mucilage  or  coagulable  lymph,  as 
in  cream  or  new  milk,  is  eafy  of  digeftion,  and  conftitutes  prob- 
ably the  mod  nutritive  part  of  animal  diet ;    as  oil  is  another 
part  of  the  chyle  of  all  animals.     As  thefe  two  materials,  fugar 
and  butter,  contain  much  nutriment  under  a  fmall  volume,  and 
readily  undergo  fome  chemical  change  fo  as  to  become  acid  or 
rancid  ;  they  are  liable  to  diflurb  weak  ftomachs,   when  taken 
in  large  quantity,  more  than  aliment,  which  contains  lefs  nour- 
ifhment,  and  is  at  the  fame  time  lefs  liable  to  chemical  changes  ; 
becaufe  the  chyle  is  produced   quicker  than  the  torpid  ladleals 
can  abforb  it,  and  thence  undergoes  a  further  chemical  procrefs. 
Sugar  and  butter  therefore  are  not  fo  eafily  digeiled,  when  ta- 
ken in  large  quantity,  as  thofe  things,  which  contain  lefs  nutri- 
ment ;  hence,  where  the  ftomach  is  weak,  they  mud  be  ufed  in 
lefs  quantity.     But  the  cuftom  of  fome   people  in  restraining 
children  entirely  from  them,  is  depriving  them  of  a  very  whole- 
fome  agreeable,   and    fubftantial  part  of  their  diet.      Honey, 
manna,  fap-juice,  are  different  kinds  of  lefs  pure  fugar. 

3.  Ail  the  efculent  vegetables  contain  a  bland  oil,  or  mucil- 
age, or  ilarch,  or  fugar,  or  acid  ;  and,  as  their  flimulus  is  mod- 
erate, are  properly  given  alone  as  food  in  inflammatory  difeai- 
es  ;    and    mixed    with  milk  conititute  the  food  of  thoufands. 
Other  vegetables  poflefs  various  degrees  and   various  kinds  of 
ilimulus  •,  and  to  thefe  we  are  beholden  for  the  greater  part  of 
our  Materia  Medica,  which  produce  naufea,  ficknefs,  vomiting, 
catharfis,  intoxication,  inflammation,   and  even  death,  if  unfkil- 
fully  adminiftered. 

The  acrid  or  intoxicating,  and  other  kinds  of  vegetable  juices, 
fuch  as  produce  ficknefs,  or  evacuate  the  bowels,  or  fuch  even 
as  are  only  difagreeable  to  the  palate,  appear  to  be  a  part  of  the 
defence  of  thofe  vegetables,  which  poflefs  them,  from  the  aflaults 
of  larger  animals  or  of  infefts.  As  mentioned  in  the  Botanic 
Garden,  Part  II.  Cant.  I.  line  1 6 1,  note.  This  appears  in  a 
forcible  manner  from  the  perufal  of  fome  travels,  which  have 
been  publiftied  of  thofe  unfortunate  people,  who  have  fuffered 
(hipwreck  on  uncultivated  countries,  and  have  with  difficulty 
found  food  to  fubfift,  in  otherwife  not  inhofpitable  climates. 

4.  As  thefe  acrid  and  intoxicating  juices  generally  rcfide  in 
the  mucilage,  and  not  in  the  ftarch  oi:  many  roots,  and  feeds, 
according  to  the  obfervation  of  M.  Parmentier,   the  wholefome 
or  nutritive  parts  of  fome  vegetables  may  be  thus  feparated  from 

the 


ip  NUTRIENTTI A.  ART.  1.2. 3 . 5. 

the  medicinal  parts  of  them.  Thus  if  the  root  of  white  briony 
be  rnfped  into  cold  water,  by  means  of  a  bread-grater  made  of 
a  tinned  iron  plate,  and  agitated  in  it,  the  acrid  juice  of  the  root 
along  with  the  mucilage  will  be  diffolved,  or  fwim,  in  the  vvater  ; 
while  a  ftarch  perfectly  wholefome  and  nutritious  will  fubfide, 
and  may  be  ufed  as  food  in  times  of  fcarcity. 

M.  Parmentier  further  obferves,  that  potatoes  contain  too 
much  mucilage  in  proportion  to  their  ftarch,  which  prevents  them 
from  being  converted  into  good  bread.  But  that  if  the  ftarch 
be  collected  from  ten  pounds  of  raw  potatoes  by  grating  them 
into  ,cold  water,  and  agitating  them,  as  abovementioned  ;  and 
if  the  ftarch  thus  procured  be  mixed  with  other  ten  pounds  of 
boiled  potatoes,  arid  properly  fubjecled  to  fermentation  like 
wheat  flour,  that  it  will  make  as  good  bread  as  the  fined  wheat. 

Good  bread  may  alfo  be  made  by  mixing  wheat  flour  with 
boiled  potatoes.  Eighteen  pounds  of  wheat-flour  are  faid  to 
make  twenty-two  pounds  and  a  half  of  bread.  Eighteen  pounds 
of  wheat-flour  mixed  with  nine  pounds  of  boiled  potatoes,  are 
fa^d  ^0  make  twenty-nine  pounds  and  a  half  of  bread.  This 
di  ;rerence  of  weight  muft  arife  from  the  difference  of  the  previ- 
ous drynefs  of  the  two  materials  The  potatoes  might  proba- 
bly make  better  flour,  if  they  were  boiled  in  (learn,  in  a  clofe 
verlel  triad e  fome  degrees  hotter  than  common  boiling  water. 

Other  vegetable  matters  may  be  deprived  of  their  too  great 
acrimony  by  boiling  in  water,  as  the  great  variety  of  the  cab- 
bage, the  young  tops  of  white  briony,  water- -crefies,  afpara^us, 
with  innumerable  roots,  and  fome  fruits.  Other  plants  have 
their  acrid  juices  or  bitter  particles  diminifhed  by  covering 
them  from  the  light  by  what  is  termed  blanching  them,  as  the 
ftems  and  leaves  of  cellery,  endive,  fea-kale.  The  former 
method  either  extracts  or  decompofes  the  acrid  part:cies,  and 
the  latter  prevents  them  from  being  formed.  See  Botanic 
Garden,  Vol.  I.  additional  note  XXXI V.  on  the  Etiolation  of 
vegetables. 

5.  The  art  of  cookery,  by  expofmg  vegetable  and  animal 
fubftances  to  heat,  has  contributed  to  increafe  the  quantity  of 
the  food  of  mankind  by  other  means  befides  that  of  deftroying 
their  acrimony.  One  of  thefe  is  by  converting  the  acerb  juices 
of  fome  fruits  into  fugar,  as  in  the  baking  of  unripe  pears,  and 
the  bruifing  of  unripe  apples;  in  both  which  fituations  the  life 
of  the  vegetable  is  defiroyed,  and  the  converfion  of  the  harfn 
juice  into  a  fweet  one  muft  be  performed  by  a  chemical  procefs  •, 
and  not  by  a  vegetable  one  only,  as  the  germination  of  barley  in 
making  malt  has  generally  been  fuppofed. 

Some  circuit! {lances,  which  feem  to  injure  the  life  of  feveral 

fruits, 


ART.  I.  2. 3. 5.  NUTRIENTIA.  i  r 

fruity  feem  to  forward  the  faccharine  procefs  of  their  juices. 
Thus  if  forne  kinds  of  pears  are  gathered  a  week  before  they 
would  ripen  on  the  tree,  and  are  laid  on  a  heap  and  covered, 
their  juice  becomes  fweet  many  days  fooner.  The  taking  off 
a  circular  piece  of  the  bark  from  a  branch  of  a  pear-tree  caufes 
the  Iruir  of  that  branch  to  ripen  fooner  by  a  fortnight,  as  I  have 
more  than  once  obferved.  The  wounds  made  in  apples  by  in- 
fer s  occafion  thofe  apples  to  ripen  fooner  ;  caprification,  or  the 
piercing  of  figs,  in  the  ifiand  of  Mrlta,  is  faicl  to  ripen  them 
footer;  and  I  am  well  informed,  that  when  bunches  ofgrapts 
in  this  country  have  acquired  their  expected  fize,  if  the  (talk  of 
each  bunch  be  cut  half  through,  they  will  fooner  ripen. 

The  germinating  barley  in  the  malt-houfe  I  believe  acquires 
little  fweetnefs,  till  the  life  of  the  feed  is  deftroyed,  and  the  fac- 
charine procefs  then  continued  or  advanced  by  the  heat  in  dry- 
ing it.  Thus  in  animal  digeflion,  the  fugar  produced  in  the 
flomach  is  abforbed  by  the  Ia6leals  as  fall  as  it  is  made,  other- 
wile  it  ferments,  and  produces  flatulency  -,  fo  in  the  germina- 
tions of  barley  in  the  malt-houfe,  fo  long  as  the  new  plant  lives, 
the  fugar,  I  fuppofe,  is  abforbed  as  fait  as  it  is  made  ;  but  that, 
which  we  ufe  in  making  beer»  is  the  fugar  produced  by  a  chem- 
ical procefs  after  the  death  of  the  young  plant,  or  which  is  made 
more  expeditioufly,  than  the  plant  can  abforb  it. 

It  is  probably  this  faccharine  procefs,  which  obtains  in  new 
hayitacks  too  hafiily,  and  which  by  immediately  running  into 
fermentation  produces  fo  much  heat  as  to  fct  them  on  fire. 
The  greateil  part  of  the  grain,  or  feeds,  or  roots,  ufed  in  the 
diftiileries,  as  wheat,  canary  feed,  potatoes,  are  not  I  believe 
previoufly  fubjecled  to  germination,  but  are  in  part  by  a  chemi- 
cal procefs  converted  into  fugar,  and  immediately  fubje&ed  to 
vinous  fermentation  ;  and  it  is  probable  a  procefs  may  fome- 
time  be  difcovered  of  producing  fugar  from  (larch  or  meal ;  and 
of  feparating  it  from  them  for  domeflic  purpofes  by  alcohol, 
which  diflblves  fugar  but  not  mucilage  ;  or  by  other  means. 

Another  method  of  increafing  the  nutriment  of  mankind  by 
cookery,  is  by  difiblving  cartilages  and  bones,  and  tendons,  and 
probably  fome  vegetables,  in  (learn  or  water  at  a  much  higher 
degree  of  heat  than  that  of  boiling.  This  is  to  be  done  in  a 
cloie  veiTel,  which  is  called  Papin's  digefter  ;  in  which,  it  is 
faict,  that  water  may  be  made  redhot,  and  will  then  diflblve  all 
animal  fubilances  *,  and  might  thus  add  to  our  quantity  of  food 
in  times  of  fcarcity.  This  veflel  mould  be  made  of  iron,  and 
fhould  have  an  oval  opening  at  top,  with  an  oval  lid  of  iron,  and 
larger  than  the  aperture  •,  this  lid  ihould  be  (lipped  in  endways, 
when  the  veffel  is  filled,  and  then  turned,  and  raifed  by  a  fcrew 

above 


i  2  NUTRIENT! A,  ART.  I.  2.  3. 6. 

above  it  into  contadl  with  the  under  edges  of  the  aperture* 
There  (hould  alfo  be  a  fmall  tube  or  hole  covered  with  a  weight- 
ed valve  to  prevent  the  danger  of  burfting  the  digefter. 

Where  the  powers  of  digeftion  are  weakened,  broths  made 
by  boiling  animal  and  vegetable  fubitances  in  water  afford  a  nu- 
triment ;  though  I  fuppofe  not  fo  great  as  the  flefh  and  vegeta- 
bles would  afford,  if  taken  in  their  folid  form,  and  mixed  with 
faliva  in  the  aft  of  maftication.  The  aliment  thus  prepared 
fhould  be  boiled  but  a  fliort  time,  nor  fhould  be  fuffered  to  con- 
tinue in  our  common  kitchen-utenfils  afterwards,  as  they  are 
lined  with  \i  mixture  of  half  lead  and  half  tin,  and  are  therefore 
unwholefome,  though  the  copper  is  completely  covered.  And 
thole  ioups,  which  have  any  acid  or  wine  boiled  in  them,  un- 
lefs  they  be  made  in  filver,  or  in  china,  or  in  thofe  pot-vef- 
fels,  which  are  not  glazed  by  the  addition  of  lead,  are  truly  poi- 
fonous  ;  as  the  acid,  as  lemon-juice  or  vinegar,  when  made  hot, 
erodes  or  diffolves  the  lead  and  tin  lining  of  the  copper  veflels, 
and  the  leaden  glaze  of  the  porcelain  ones.  Hence,  where  fil- 
ver cannot  be  had,  iron  veflels  are  preferable  to  tinned  copper 
ones  ;  or  thofe  made  of  tinned  iron-plates  in  the  common  tin- 
ihops,  which  are  faid  to  be  covered  with  pure  or  block  tin. 

6.  Another  circumftance,  which  facilitates  the  nourifhment 
of  mankind,  is  the  mechanic  art  of  grinding  farinaceous  feeds 
into  powder  between  mill-Hones  ;  which  may  be  called  the  ar* 
tificial  teeth  of  fociety.  It  is  probable,  that  fome  foft  kinds  of 
wood,  efpecially  when  they  have  undergone  a  kind  of  fermenta- 
tion, and  become  of  loofer  texture,  might  be  thus  ufed  as  food 
in  times  of  famine. 

Nor  is  it  improbable,  that  hay,  which  has  been  kept  in  (lacks, 
fo  as  to  undergo  the  faccharine  procefs,  may  be  fo  managed  by 
grinding  and  by  fermentation  with  yeail  like  bread,  as  to  ferve 
in  part  for  the  fuftenance  of  mankind  in  times  of  great  fcarcity. 
Dr.  Prieitley  gave  to  a  cow  for  fome  time  a  ftrong  infufion  of 
hay  in  large  quantity  for  her  drink,  and  found  that  (lie  produ- 
ced during  this  treatment  above  double  the  quantity  of  milk. 
Hence  if  bread  cannot  be  made  from  ground  hay,  there  is  great 
reafon  to  fufpeft,  that  a  nutritive  beverage  may  be  thus  prepared 
either  in  its  faccharine  ftate,  or  fermented  into  a  kind  of  beer. 

In  times  of  great  fcarcity  there  are  other  vegetables,  which 
though  not  in  common  ufe,  would  moft  probably  afford  whole- 
fome  nourifhment,  either  by  boiling  them, or  drying  and  grinding 
them,  or  by  both  thofe  proceffes  in  fucceilion.  Of  thefe  are  per- 
haps the  tops  and  the  bark  of  all  thofe  vegetables,  which  are 
armed  with  thorns  or  prickles,  as  goofeberry  trees,  holly,  gorfe, 
and  perhaps  hawthorn.  The  inner  bark  of  the  elm  tree  makes 


ART.  I.  2. 3.  7.  NUTRIENTIA.  13 

a  kind  of  gruel.  And  the  roots  of  fern,  and  probably  of  very 
many  other  roots,  as  ef  grafs  and  of  clover  taken  up  in  winter, 
might  yield  nourifhment  either  by  boiling  or  baking,  and  fepa- 
rating  the  fibres  from  the  pulp  by  beating  them  •,  or  by  getting 
only  the  (larch  from  thofe,  which  poflefs  an  acrid  mucilage,  as 
the  white  briony.  And  the  alburnum  of  perhaps  all  trees,  and 
efpecially  of  thofe  which  bleed  in  fpring,  might  produce  a  fac- 
charine  and  mucilaginous  liquor  by  boiling  it  in  the  winter  or 
fpring. 

7.  However  the  arts  of  cookery  and  of  grinding  may  in- 
creafe  or  facilitate  the  nourifhment  of  mankind,  the  great  fource 
of  it  is  from  agriculture.  In  the  favage  tlate,  where  men  live 
folely  by  hunting,  I  was  informed  by  Dr.  Franklin,  that  there 
was  feldom  more  than  one  family  exifted  in  a  circle  of  five  miles 
diameter  ;  which  in  a  flate  of  pafturage  would  fupport  fome 
hundred  people,  and  in  a  flate  of  agriculture  many  thoufands. 
The  art  of  feeding  mankind  on  fo  fmall  a  grain  as  wheat,  which 
feemsto  have  been  difcovered  in  Egypt  by  the  immortal  name 
of  Ceres,  (hewed  greater  ingenuity  than  feeding  them  with  the 
large  roots  of  potatoes,  which  feem  to  have  been  a  difcovery  of 
ill-fated  Mexico. 

This  greater  production  of  food  by  agriculture  than  by  paftur- 
age,  fhews  that  a  nation  nourifhed  by  animal  food  will  be  lefs  nu- 
merous than  if  nourilheu  by  vegetable-,  and  the  former  will  there- 
fore be  liable,  if  they  ave  engaged  in  war,  to  be  conquered  by 
the  latter,  as  Abel  was  ilain  by  Cain.  This  is  perhaps  the  only 
valid  argument  againft  inciofing  open  arable  fields.  The  great 
production  of  human  nourifhment  by  agriculture  and  pafturage 
evinces  the  advantage  of  fociety  over  the  favage  flate  ;  as  the 
number  of  mankind  becomes  increafed  a  thoufand  fold  by  the 
arts  of  agriculture  and  pafturage  ;  and  their  happinefs  is  proba- 
bly under  good  governments  improved  in  as  great  a  proportion, 
as  they  become  liberated  from  the  hourly  fear  of  beads  of  prey, 
from  the  daily  fear  of  famine,  and  of  the  occafional  incurfioiis 
of  their  cannibal  neighbours. 

But  pafturage  cannot  exift  without  property  both  in  the  foil, 
and  the  herds  which  it  nurtures  ;  and  for  the  invention  of  arts, 
and  production  of  tools  necefTary  to  agriculture,  fome  muft  think, 
and  others  labour  ;  and  as  the  efforts  of  fome  will  be  crowned 
with  greater  fuccefs  than  that  of  others,  an  inequality  of  the 
ranks  of  fociety  muft  fucceed  ;  but  this  inequality  of  mankind  in 
the  prefent  flate  of  the  world  is  too  great  for  the  purpoies  of  pro- 
ducing the  greateft  quantity  of  human  nourifhmtnt,  and  the 
greatefl  ium  of  human  happinefs ;  there  mould  be  no  flavery  at 
one  end  of  the  chain  of  fociety,  and  no  defpotifm  at  the  other.— 

Bv 


J4  NUTRIENTIA.  ART.  I.  2.4.1. 

By  the  future  improvements  of  human  reafon  fuch  govern- 
ments may  poflibly  hereafter  be  eftabliflied,  as  may  a  hundred- 
fold increafe  the  numbers  of  mankind,  and  a  thoufand-fold  their 
happinefs. 

IV.  i.  Water  mud  be  confidered  as  a  part  of  our  nutriment, 
becaufe  ib  much  of  it  enters  the  compofition  of  our  folicis  as 
well  as  of  our  fluids  ;  and  becaufe  vegetables  are  now  believed 
to  draw  almoft  the  whole  of  their  nourilhment  from  this  tource, 
As  in  them  the  water  is  decompofed,  as  it  is  perfpired  by  them 
in  the  funfhine,  the  oxygen  gas  increases  the  quantity  and  the 
purity  of  the  atmofphere  in  their  vicinity,  and  the  hydrogen 
leems  to  be  retained,  and  to  form  the  nutritive  juices,  and  con- 
fequent  fecretions  of  refin,  gum,  wax,  honey,  oil,  and  other  veg- 
etable productions.  See  Botanic  Garden,  Part  I  Cant.  IV. 
line  25,  note.  It  has  however  other  ufes  in  the  fvnVm,  befides 
that  of  a  nourifhing  material,  as  it  dilutes  our  fluids,  and  lubri- 
cates our  folids  ;  and  on  all  thefe  accounts  a  daily  fupply  of  it  is 
required. 

2.  River- water  is  in  general  purer  than  fpring- water  ;  as  the 
neutral  falts  wafhed  down  from  the  earth  decompofe  each  other 
except  perhaps  the  marine  fait  ;  and  the  earths,  with  which 
fpring-water  frequently  abounds,  is  precipitated  ;  yet  it  is  not 
improbable,  that  the  calcareous  earth  diflblved  in  the  water  of 
many  fprings  may  contribute  to  our  nourimment,  as  the  water 
from  fprings,  which  contain  earth,  is  faicl  to  conduce  to  enrich 
thofe  lands,  which  are  flooded  with  it,  more  than  river  water. 

The  Chinefe  are  faid,  by  Sir  G.  Staunton,  to  purify  the  water 
of  fome  muddy  rivers  or  canals,  by  ftirrin^  them  with  a  hollow 
cane  full  of  fmall  holes,  in  the  tube  of  which  are  enclofed  fome 
pieces  of  alum.  And  the  bakers  in  London  aflert,  that  one  ufe 
of  alum  is  to  clear  the  New  River  water,  and  thus  to  render 
their  bread  whiter.  Where  any  volatile  alkali  is  mixed  with 
water,  as  often  happens  from  the  liable  dung  and  other  ordure 
of  populous  towns,  it  will  be  converted  to  vitriolic  ammoniac  by 
a  folution  of  alum  ;  and  calcareous  earth  may  be  converted  into 
gypfum,  and  fubfide  along  with  the  earth  of  the  alum.  See 
ClafsII.  1.6.  1 6. 

^3.  Many  arguments  feem  to  (hew,  that  calcareous  earth  con- 
tributes to  the  nourifhment  of  animals  and  vegetables.  Firft 
becaufe  calcareous  earth  conftitutes  a  confiderable  part  of  them, 
and  muft  therefore  either  be  received  from  without,  or  formed 
by  them,  or  both,  as  milk,  when  taken  as  food  by  a  la&efcent 
woman,  is  decompofed  in  the  ftomach  by  the  procefs  oi  digef- 
tion,and  again  in  part  converted  into  milk  by  the  peftoral  glands, 
Secondly,  becaufe  from  the  analogy  of  all  organic  life,  whatever 

has 


ART-  I.  2.  4.  3.  NUTRIENTIA.  J5 

has  compofed  a  part  of  a  vegetable  or  animal  may  again  after 
its  chemical  folution  become  a  part  of  another  vegetable  or  an- 
imal, fuch  is  the  general  tranfmigration  of  matter.  And  thirdly, 
becaufe  the  great  ufe  of  lime  in  agriculture  on  almoft  all  kinds 
of  foil  and  fituation  cannot  be  fatisfa£lorily  explained  from  its 
chemical  properties  alone.  Though  thefe  may  alfo  in  certain 
foils  and  fituations  have  confiderable  effect. 

The  chemical  ufes  of  lime  in  agriculture  may  be,  i.  from  its 
deftroying  in  a  fhort  time  the  cohefion  of  dead  vegetable  fibres, 
and  thus  reducing  them  to  earth,  which  otherwife  is  effected  by 
a  flow  procefs  either  by  the  confumption  of  infects  or  by  a 
gradual  putrefaction.  Thus  I  am  informed  that  a  mixture  of 
lime  with  oak  bark,  after  the  tanner  has  extracted  from  it  what- 
ever is  foluble  in  water,  will  int»'o  or  three  months  reduce  it 
to  a  fine  black  earth,  which,  if  only  laid  in  heaps,  it  would  re- 
quire as  many  years  to  effect  by  its  own  fponraneous  fermenta- 
tion or  putrefaction.  This  effect  of  lime  muft  be  particularly  ad- 
vantageous to  newly  enclofed  commons  when  firfl  broken  up. 

Secondly,  lime  for  many  months  continues  to  attract  moifture. 
from  the  air  or  earth,  which  it  deprives  I  fuppofe  of  carbonic 
acid,  and  then  fuffers  it  to  exhale  again,  as  is  feen  on  the  plaf* 
tered  walls  of  new  houfes.  On  this  account  it  muft  be  advan- 
tageous when  mixed  with  dry  or  fandy  foils,  as  it  attracts  moif- 
ture from  the  air  above  or  the  earth  beneath,  and  this  moifture 
is  then  abforbed  by  the  lymphatics  of  the  roots  of  vegetables. 
Thirdly,  by  mixing  lime  with  clays  it  is  believed  to  make  them 
lefs  cohefive,  and  thus  to  admit  of  their  being  more  eafily  pen- 
etrated by  vegetable  fibres.  A  mixture  of  lime  with  clays  de- 
itroys  their  fuperabundancy  of  acid,  if  fuch  exifts,  and  by  unit- 
ing with  it  converts  it  into  gypfum  or  alabafter.  And  laftly, 
frefh  lime  deftroys  worms,  fnails,  and  other  infects,  with  which 
it  happens  to  come  in  contact. 

Yet  do  not  all  thefe  chemical  properties  feem  to  account  for 
the  great  ufes  of  lime  in  almoft  all  foils  and  fituations,  as  it  con- 
tributes fo  much  to  the  melioration  of  the  crops,  as  well  as  to 
their  increafe  and  quantity.  Wheat  from  land  well  limed  is 
believed  by  farmers,  millers,  and  bakers,  to  be,  as  they  fuppofe, 
thinner  fkinned  ;  that  is,  it  turns  out  more  and  better  flour  ; 
which  I  fuppofe  is  owing  to  its  containing  more  ftarch  and 
lefs  mucilage.  In  refpect  to  grafs- ground  I  am  informed,  that 
if  a  fpadeful  of  lime  be  thrown  on  a  tufibck,  which  horfes  or 
cattle  have  refufed  to  touch  for  years,  they  will  for  many  fuc- 
ceeding  feafonseat  it  quite  clofe  to  the  ground. 

One  property  of  lime  is  not  perhaps  yet  well  underftood,  I 
mean  its  producing  fo  much  heat,  when  it  is  mixed  with  water  ; 

VOL.  I.  O  o  o  v/hich 


i6  NUTRIENTIA.  ART.I.  a.  4.4. 

which  may  be  owing  to  the  elementary  fluid  of  heat  confolidated 
in  the  lime.  It  is  the  fleam  occasioned  by  this  heat,  when  water 
is  fprinkled  upon  lime,  if  the  water  be  not  in  too  great  quan- 
tity or  too  cold,  which  breaks  the  lime  into  fuch  fine  powder  as 
almod  to  become  fluid,  which  cannot  be  effefted  perhaps  by 
any  other  means,  and  which  I  fuppofe  mud  give  great  prefer- 
£nce  to  lime  in  agriculture,  and  to  the  folutions  of  calcareous 
earth  in  water,  over  chalk  or  powdered  lime-done,  when  fpread 
upon  the  land. 

4.  It  was  formerly  believed  that  waters  replete  with  calcare- 
ous earth,  fuch  as  incruft  the  infide  of  tea  kettles,  or  are  faid  to 
petrify  mofs,  were  liable  to  produce  or  to  increafethe  (lone  in 
the  bladder.  This  miflaken  idea  has  lately  been  exploded  by 
the  improved  chemiftry,  as  nr^  calcareous  earth,  or  a  very  minute 
quantity,  was  foundi  in  the  calculi  analyfed  by  Scheele  and  Berg- 
man. The  waters  of  Matlock  and  of  Carl  (bad,  both  which  cover 
the  mofs,  which  they  pafs  through,  with  a  calcareous  cruft,  are 
fo  far  from  increafing  the  done  of  the  bladder  or  kidneys,  that 
thofe  of  Carlfbad  are  clebrated  for  giving  relief  to  thofe  labour- 
ing under  thefe  difeafes.  Philof.  Tranf.  Thofe  of  Matlock 
are  drunk  in  great  quantities  without  any  fufpicion  of  injury  ; 
and  I  well  know  a  perfon  who  for  above  ten  years  has  drunk 
about  two  pints  a  dav  of  cold  water  from  a  fpring,  which  very 
much  incrufts  the  veffels,  it  is  boiled  in,  with  calcareous  earth, 
and  affords  a  copious  calcareous  fediment  with  a  folution  of  fait 
of  tartar,  and  who  enjoys  a  date  of  uninterrupted  health. 

V.  i.  As  animal  bodies  confid  much  both  of  oxygen  and 
azote,  which  make  up  the  compofition  of  atmofpheric  air,  thefe 
fhould  be  counted  amonsfl:  nutritious  fubilances.  Befides  that 
by  the  experiments  of  Dr  Priedley  it  appears,  that  the  oxygen 
gains  admittance  into  the  blood  through  the  moid  membranes 
of  the  lungs ;  and  feems  to  be  of  much  more  immediate  conTe- 
quence  to  the  prefervation  of  our  lives  than  the  other  kinds  of 
nutriment  above  fpecified. 

As  the  bafis  of  fixed  air,  or  carbonic  acid  gas,  is  carbone, 
which  alfo  conditutes  a  great  part  both  of  vegetable  and  animal 
bodies  ;  this  air  fhould  Hkewife  be  reckoned  amongd  nutritive 
fubdances.  Add  to  this,  that  when  this  carbonic  acid  air  is 
fwallowed,  as  it  efcapes  from  beer  or  cyder,  or  when  water  is 
charged  with  it  as  detruded  from  limeftone  by  vitriolic  acid,  it 
affords  an  agreeable  fenfation  both  to  the  palate  and  ftomach, 
and  is  therefore  probably  nutritive. 

The  immenfe  quantity  of  carbone  and  of  oxygen  which  con- 
flitute  fo  great  a  part  of  the  limedone  countries  is  almod  be- 
yond conception,  and,  as  it  has  been  formed  by  animals,  may 

again 


ART.  1.2.  6.  i.  NUTRIENTIA.  17 

again  become  a  part  of  them,  as  well  as  the  calcareous  matter 
with  which  they  are  united.  Whence  it  may  be  conceived, 
that  the  waters,  which  abound  with  limeftone  in  folution,  may 
fupply  nutriment  both  to  animals  and  to  vegetables,  as  mention- 
ed above. 

VI.  i.  The  manner,  in  which  nutritious  particles  are  fub- 
flituted  in  the  place  of  thofe,  which  are  mechanically  abraded, 
or  chemically  decompofed,  or  which  vanifh  by  animal  abforp- 
tion.  mull  be  owing  to  animal  appetency,  as  defcribed  in  Seel:. 
XXXVII.  3.  and  is  probably  fimilar  to  the  procels  of  inflamma- 
tion, which  produces  new  veflels  and  new  fluids  ;  or  to  that 
which  conflitutes  the  growth  of  the  body  to  maturity.  Thus 
the  granulations  of  new  flefh  to  repair  the  injuries  of  wounds 
are  vifible  to  the  eye  ;  as  well  as  the  callous  matter,  which  ce- 
ments broken  bones  ;  the  calcareous  matter,  which  repairs  in- 
jured fnail-ihells  ;  and  the  threads,  which  are  formed  by  filk- 
worms  and  fpiders  ;  which  are  all  fecreted  in  a  fofter  date,  and 
harden  by  exfkcation,  or  by  the  contact;  of  the  air,  or  by  abforp- 
tion  of  their  more  fluid  parts. 

Whether  the  materials,  which  thus  fupply  the  wade  of  the 
fyftem,  can  be  given  any  other  way  than  by  the  ftomach,  fo  as 
to  preferve  the  body  for  a  length  of  time,  is  worth  our  inquiry  ; 
as  cafes  fometimes  occur,  in  which  food  cannot  be  introduced 
into  the  ftomach,  as  in  obftruclions  of  the  ceiophagus,  inflam- 
mations of  the  throat,  or  in  hydrophobia  ;  and  other  cafes  are 
not  unfrequent  in  which  the  power  of  digeftion  is  nearly  or  to- 
tally deftroyed,  as  in  anorexia  epileptica,  and  in  many  fevers. 

In  the  former  of  thefe  circumftances  liquid  nutriment  may 
fometimes  be  gotten  into  the  Itomach  through  a  flexible  cathe- 
ter ;  as  defcribed  in  Clafs  III.  i.  I.  15.  In  the  latter  many 
kinds  of  mild  aliment,  as  milk  or  brorh,  have  frequently  been 
injected  as  clyfters,  together  with  a  fmall  quantity  of  opium,  as 
ten  drops  of  the  tinfture,  three  or  four  times  a  ciay  ,  to  which 
alfo  might  be  added  very  fmall  quantities  of  vinous  Ipirit  But 
thtfe,  ab  far  as  I  have  obftrved,  will  not  long  iultain  a  perfon, 
who  cannot  take  any  fuftenance  by  the  {tomach. 

2  Another  mode  of  applying  nutritive  fluids  might  be  by 
exrenfive  fomentations,  or  by  immerging  the  whole  body  in  a 
bath  of  broth,  or  of  warm  milk,  which  might  at  the  fame  time 
be  coagulated  by  rennet,  or  the  acid  ot  the  calf's  {tomach  ;  broth 
or  whey  might  thus  probably  be  introduced,  in  part  at  Jeaft,  into 
the  circulation,  as  a  folution  of  nitre  is  faid  to  have  been  ab- 
forbed  in  a  pediluvium,  which  was  afterwards  difcovered  by  the 
manner  in  which  paper  dipped  frequently  in  the  urine  of  the  pa- 
tient and  dried,  burnt  and  fparkled  like  touch-paper.  Great 

quantity 


1 8  .         NUTRIENTIA,  AR  T.  1. 2. 6.  3. 

quantity  of  water  is  alfo  known  to  be  abforbed  by  thofe,  who 
have  bathed  in  the  warm  bath  after  exercife  and  abftinence  from 
liquids.  Cleopatra  was  faid  to  travel  with  4000  milch-aiTes 
in  her  train,  and  to  bathe  every  morning  in  their  milk, 
which  Che  probably  might  ufe  as  a  cofmetic  rather  than  a 
nutritive. 

3    The   transfufion  of  blood  from  another  animal  into  the 

vein  of  one,  who  could  take  no  fuftenance   by  the  throat,  or  di- 

geft  none  by  the  ftomach,  might  long  continue  to  fupport  him  ; 

anci  perhaps  other  nutriment,  as  milk  or  mucilage,  might  be  this 

ntroduced  into  the    fyftem,  but  we  have  not  yet  fu Ancient 

:  nents  on  this  fubjeft.     See  Seel.  XXXII.  4.  and  Clafs  I. 

2.  3    25    and  Sup.  I   14.  2- 

VII  Various  kinds  of  condiments,  or  fauces,  have  been  tak- 
en alon-?  with  vegetable  or  animal  food,  and  have  been  thought 
by  feme  to  ftrengthen  the  procefs  of  digeftion  and  confequent 
procefs  of  nutrition.  Of  thefe  wine,  or  other  fermented  liquors, 
vinegar,  fait,  fpices,  and  muftard,  have  been  in  mod  common 
ufe.  and  I  believe  to  the  injury  of  thoufands.  As  the  ftomach 
.  eir  violent  ftimulus  at  length  lofes  its  natural  degree  of  ir- 
ritability, and  indigeftion  is  the  confequerice  *,  which  is  attend- 
ed wich  flatulency  and  emaciation.  Where  any  of  thefe  have 
been  taken  fo  long  as  to  induce  a  habit,  they  muft  either  be 
continued,  but  not  increafed  ;  or  the  ufe  of  them  (hould  be 
gradually  and  cautioufly  diminiflied  or  difcontinued,  as  directed 
in  Seel.  XII.  7.  8. 

III.  CATALOGUE  OF  THE  NUTRIENTIA. 

I.  i.  Venifon,  beef,   mutton,  hare,  goofe,  duck,  woodcock, 

fnipe,  moor-game. 

:,  Oyfters,    lobfters,    crabs,    fhrimps,    mufhrooms,  eel, 
tench,  barbolt,  fmelt,  turbot,  fole,  turtle. 

3.  Lamb,  veal,  fucking-pig. 

4.  Turkey,  partridge,  pheafant,  fowl,  eggs. 

5.  Pike:  perch,  gudgeon,  trout,  grayling. 

II.  Milk,  cream,  butter,  buttermilk,  whey,  cheefe. 

III.  Wheat,  barley,  oats,  peafe,  potatoes,  turnips,  carrots,  cab- 

bage, afparagus,  artichoke,  fpinach,  beet,  apple,  pear, 
plum,  apricot,  nectarine,  peach,  ftrawberry,  grape,  or- 
ange, melon,  cucumber,  dried  figs,  raifins,  fugar,  honey. 
With  a  great  variety  of  other  roots,  feeds,  leaves,  and 
fruits. 

IV.  Water,  river- water,  fpring- water,  calcareous  earth. 

V.  Air, 


ART.  II.  i.  i.  i.  INCITANTIA.  19 

V.  Air,  oxygene,  azote,  carbonic  acid  gas. 
VI   Nutritive  baths  and  clyfters,  transfufion  of  blood. 
VII.  Condiments. 


ART.  II. 
IXCITANTIA. 

I.  i.  THOSE  THINGS,  which  increafe  the  exertions  of  all 
the  irritative  motions,  are  termed  incitantia.  As  alcohol,  or 
the  fpirituous  part  of  fermentated  liquors,  opium,  and  many 
drugs,  which  are  dill  efteemed  poifons,  their  proper  dofes  not 
being  afcertained.  To  thefe  fhould  be  added  the  exhilerating 
paflions  of  the  mind,  as  joy,  love  :  and  externally  the  applica- 
tion of  heat,  electricity,  ether,  eflential  oils,  friclion,  and  ex- 
erci 

2  Thefe  promote  both  the  fecretions  and  abforptions,  in- 
creafe  the  natural  heat,  and  remove  thofe  pains,  which  origin, 
ate  from  the  defect  of  irritative  motions,  termed  nervcus  pains ; 
and  prevent  the  convulfions  confequent  to  them.  When  given 
internally  they  induce  coftivenefs,  and  deep  coloured  urine  ; 
and  by  a  greater  dofe  intoxication,  and  its  confequenc 

II.  OBSERVATIONS  ON  THE  INCITANTIA. 

1.  i.  Opium  and  alcohol  increafe    all  the  fecretions  and  ab- 
forptions.    The  increafe  of  the  fecretion  of  fenforial  power  ap- 
pears from  the  violent  exertions  of  drunken  people  ;   the  fecre- 
tion of  fweat  is  more  certainly  excited  by  opium   or  wine  than 
by  any  other  medicine  ;  and  the  increafe  of  general  heat,  which 
theie  drugs  produce,  is  an  evidence  of  their  effect  in  promoting 
all  the  fecretions  ;     fince  an  increafe  of  fecretion  is  always  at- 
tended with  increafe  of  heat  in  the  part,  as  in  hepatic  and  other 
inflammations 

2.  But  as  they  at  the  fame  time  promote  abforption  ;  thofe 
fluids,  which  are  fecreted  into  receptacles,  as  the  urine,  bile,  in- 
tcftinal  and  pulmonary  mucus,  have  again  their  thinner  parts 
abforbed  ;     and  hence,  though   the  quantity  of  fecreted    fluid 
was  increafed,  yet  as  the  abforption  was  alib  increafed,  the  ex- 
cretion from  thefe  receptacles  is  lefiened  ;  at  the  fame  time  that 
it  is  deeper  coloured  or  of  thicker  confiftence,  as  the  urine,  al- 

vine 


20  INCITANTIA.  ART  II.  2.  i.  3. 

vine  feces,  and  pulmonary  mucus.  Whereas  the  perfpiration 
being  fecreted  on  the  furface  of  the  body  is  vifible  in  its  increaf- 
ed  quantity,  before  it  can  be  reabforbed  ;  whence  arifes  that 
erroneous  opinion,  that  opium  increafes  the  cutaneous  fecretion, 
and  leffens  all  the  others. 

3.  It  muft  however  be  noted,    that  after  evacuations  opium 
feems  ^o  promote   the  abforprions  more  than  the  fecretions ;  if 
you  except  that  of  the  feniorial  power  in  the  brain,  which  prob- 
ably  fuffers  no   abforption.     Hence  its  efficacy   in  reftraining 
haemorrhages,  after  the  veflels  are  emptied,  by  promoting  vinous 
abforption. 

4.  In  ulcers  the  matter  is  thickened  by  the  exhibition  of  opi- 
um from  the  increafed  abforprion  of    the  thinner  parts  of  it; 
but  it  is  probable,   that  the  whole  fecretion,  including  the  part 
which  is  abforbed,    is  increafed  ;  and  hence  new  fibres  are  fe- 
creted along  with  the  matter,  and  the  ulcer  fills  with  new  gran- 
ulations of  flefh.     But  as  no  ulcer  can  heal,  till  it  ceafes  to  dif- 
charge  ;  that  is,  till  the  abforption  becomes  as  great  as  the  ex- 
cretion ;  thofe  medicines,   which  promote  abforption  only,  are 
more    advantageous  for   the  healing   an  ulcer  after  it  is  filled 
with  new  flefh  ;  as  the  Peruvian  bark  internally,  with  banda- 
ges and  folutions  of  lead  externally. 

5.  There  are  many  pains  which  originate  from  a  want  of  due 
motion  in  the  part,  as  thofe  occafioned  by  cold  ;  and  all  thofe 
pains  which  are  attended  with  cold  extremities,  and  are  gener- 
ally termed  nervous.     Thefe    are  relieved  by   whatever  excites 
the  part  into  its  proper  actions,  and  hence  by  opium  and  alco- 
hol ;  which  are  the  mod  univerfal  (timulants  we  are  acquaint- 
ed  with      In  thefe  cafes   the  efTVcl  of  opium  is  produced,  as 
foon  as  the  body  becomes  generally  warm  j  and  a  degree  of  in- 
toxication or  ileep  follows  the  ceflation  of  the  pain. 

Thefe  nervous  pains  (as  they  are  called)  frequently  return  at 
certain  periods  of  time,  and  are  alfo  frequently  fucceeded  by 
convulfions  ;  in  thefe  cafes  if  opium  removes  the  pain,  the  con- 
vulfions  do  not  come  on.  For  this  purpofe  it  is  Deft  to  exhibit 
it  gradually,  as  a  grain  every  hour,  or  half  hour,  till  it  intoxi- 
cates. Here  it  is  muft  be  noted,  that  a  much  lefs  quantity  will 
prevent  the  periods  of  theie  cold  pains,  than  is  neceflary  to  re- 
lieve them  after  their  accefs.  As  a  grain  and  half  of  opium 
given  an  hour  before  the  expected  paroxyfm  will  prevent  the 
cold  fit  of  an  intermittent  fever,  but  will  not  foon  remove  it, 
when  it  is  already  formed.  For  in  the  former  cafe  the  ufual 
or  healthy  aflbciations  or  catenations  of  motion  favour  the  effect 
of  the  medicine  ;  in  the  latter  cafe  thefe  affociations  or  catena- 
tions 


ART.  II.  2.  i.  6.  INCITANTI  A.  21 

tions  are  difordered,  or  interrupted,  and  new  ones  are  formed, 
which  fo  far  counteract  the  effect  of  the  medicine. 

When  opium  has  been  required  in  large  dofes  to  eafe  or  pre- 
vent convulfions,  fome  have  advifed  the  patient  to  omit  the  ufe 
of  wine,  as  a  greater  quantity  of  opium  might  then  be  exhibit- 
ed ;  and  as  opium  feems  to  increafe  abforption  more,  and  fe- 
cretion  lefs,  than  vinous  fpirit :  it  may  in  fome  cafes  be  ufeful 
to  exchange  one  for  the  other;  as  in  difeafes  attended  with  too 
great  evacuation,  as  diarrhoea,  and  dyfentery,  opium  may  be 
preferable;  on  the  contrary  in  tetanus,  or  locked  jaw,  where 
inflammation  of  the  fyftem  might  be  of  fervice,  wine  may  be 
preferable  to  opium  ;  fee  Clafs  III.  1.1.12.  I  have  generally 
obferved,  that  a  mixture  of  fpirit  of  wine  and  warm  water,  giv- 
en alternately  with  the  dofes  of  opium,  has  fooneft  and  moft 
certainly  produced  that  degree  of  intoxication,  which  was  necef- 
fary  to  relieve  the  patient  in  the  epilepfia  dolorifica. 

The  external  application  of  opium  may  alfo  be  ufed  with  ad- 
vantage, and  efpecially  when  the  ftomach  rejects  its  internal  ufe  ; 
for  this  purpofe  I  have  directed  the  whole  fpine  of  the  back  to 
be  moiftened  with  tincture  of  opium  with  fuccefs  in  epileptic 
convulfions.  And  an  extenfive  friction  with  a  liniment  confid- 
ing of  fix  grains  of  opium,  well  triturated  with  an  ounce  of  hog's 
fat,  has  lately  been  faid  to  induce  fleep  in  maniacal  cafes,  by 
Dr.  L.  Frank  of  Florence. 

Injections  of  a  folution  or  tincture  of  opium  into  the  rectum 
aft  on  the  general  constitution,  but  require  about  double  the 
quantity  for  that  purpofe  as  when  taken  into  the  (tomach.  In- 
jections of  a  folution  of  opium  into  the  urethra  may  be  of  fervice 
to  relieve  pain,  or  to  produce  the  abforption  of  the  new  veflels 
produced  by  inflammation,  after  fufficient  evacuations,  as  is  feen 
when  it  is  applied  to  an  inflamed  eye.  Or  laftly,  to  alleviate 
the  pain  from  acrid  difcharges  by  increafing  their  abforption,  or 
the  pain  from  torpor  of  the  part,  as  in  fome  tooth-achs,  by  its 
external  application. 

6-  There  is  likewife  fome  relief  given  by  opium  to  inflamma- 
tory pains,  or  thofe  from  excefs  of  motion  in  the  atFefted  part  ; 
but  with  this  difference,  that  this  relief  from  the  pains,  and  the 
fleep,  which  it  occafions,  do  not  occur  till  fome  hours  after  the 
exhibition  of  the  opium.  This  requires  to  be  explained  ;  after 
the  ftimulus  of  opium  or  of  alcohol  ceafes,  as  after  common 
drunkennefs,  a  confcquent  torpor  comes  on  ;  and  the  whole 
habit  becomes  lefs  irritable  by  the  natural  (limuli.  Hence  the 
head-achs,  ficknefs,  and  languor,  on  the  next  day  after  intoxica- 
tion, with  cold  {kin,  and  general  debility.  Now  in  pains  from 
excefs  of  motion,  called  inflammatory  pains,  when  opium  is  giv- 
en. 


22  INCITANTIA.  ART.  II.  2.  i.  7. 

en,  the  pain  is  not  relieved,  till  the  debility  comes  on  after  the 
ftimulus  ceafes  to  aft  ;  for  then  after  the  greater  (timulus  of  the 
opium  has  exhaufted  much  of  the  fenforial  power,  the  lefs  ftim- 
ulus, which  before  caufed  the  pain,  does  riot  now  excite  the  part 
into  unnatural  aftion. 

In  thefe  cafes  the  ftimulus  of  the  opium  firft  increafes  the  pain ; 
and  it  fometimes  happens,  that  fo  great  a  torpor  follows,  as  to 
produce  the  death  or  mortification  of  the  affected  part  •,  whence 
the  danger  of  giving  opium  in  inflammatory  difeafes,  efpeciaily 
in  inflammation  of  the  bowels  ;  but  in  general  the  pain  returns 
with  its  former  violence,  when  the  torpor  above  mentioned 
ceafes.  Hence  thefe  pains  attended  with  inflammation  are  beft 
relieved  by  copious  venefeftion,  other  evacuations,  and  the  clafs 
of  medicines  called  torpentia. 

7.  Thefe  pains  from  excefs  of  motion  are  attended  with  in- 
creafed  heat  of  the  whole,  or  of  the  afFefted  part,  and  a  itrong 
quick  pulfe  ;  the  pains  from  defeft  of  motion  are  attended  with 
cold  extremities,  and  a  weak  pulfe  ;  which  is  alib  generally  more 
frequent  than  natural,  but  not  always  fo. 

8.  Opium  and  alcohol  are  the  only  two  drugs,   we  are  much 
acquainted  with,   which  intoxicate  ;    and  by  this  circumftance 
are    eafily  diftinguifhed   from    the    fecernentia  and  forbentia. 
Camphor,    and  cicuta,    and  nicotiana,  are  thought  to  induce  a 
kind  of  intoxication  ;  and  there    are  many  other  drugs  of  this 
clafs,  whofe  effefts  are  lefs  known,  or  their  dofes  not  afcertain- 
ed  ;  as  atropa^  belladonna,    hyofcyamus,    ftramonium,  primus 
laurocerafus,  menifpermum,  cynogloflum,  fome  fungi,  and  the 
water   diftilled  from  black  cherry- ftones;   the  laft  of  which  was 
once  much  in  ufe  for  the  convulfions  of  children,  and  was  faid 
to  have  good  efTeft ;  but  is   now  improvidently  left  out  of  our 
pharmacopoeias.     I  have   known  one  leaf  of  the  laurocerafus, 
ihred  and  made  into  tea,  given  every  morning  for  a  week  with 
no  ill  confequence  to  a  weak  hyfteric  lady,  but  rather  perhaps 
with  advantage. 

It  is  probable,  that  other  bitter  kernels,  as  thofe  of  horfe-chef- 
nuts,  and  of  acorns,  ssfculus  hippocaftanum,  and  quercus  robur, 
may  polTefs  fomewhat  of  an  intoxicating  quality  ;  and  by  this 
kind  of  ftimulus,  as  well  as  by  their  bitter  part,  may  be  ufed  to 
prevent  the  paroxyfm  of  an  ague,  if  adminiftered  an  hour  be- 
fore the  expefted  accefs  of  it,  as  is  lately  affirmed  by  Dr  Fuchs 
of  Jena  ;  who  fays,  an  extraft  prepared  from  the  ripe  kernels  of 
the  horfe-chefnut  afts  like  an  extra  ft  of  Peruvian  bark  ;  and 
adds  that  the  bark  alfo  of  this  tree  is  ufed  with  fuccefs  inftead 
of  the  Peruvian  bark. 

9.  The  pernicious  effefts  of  a  continued  ufe  of  much  vinous 

fpirit 


ART.  II.  2.  i.  10.  INCITANT1A.  33 

fpirit  is  daily  feen  and  lamented  by  phyficians  ;  not  only  early 
debility,  like  premature  age,  but  a  dreadful  catalogue  of  difeafes 
is  induced  by  this  kind  of  intemperance  ;  as  dropfy,  gout,  lep- 
rofy,  epilepfy,  infanity,  as  defcribed  in  Botanic  Garden,  Part  II. 
Canto  III  line  357.  The  (tronger  or  lefs  diluted  the  fpirit  is 
taken,  the  fooner  it  feems  to  deflroy,  as  in  dram-drinkers  ;  but 
(till  fooner,  when  kernels  of  apricots,  or  bitter  almonds,  or  lau- 
rel-leaf, are  infufed  in  the  fpirit,  which  is  termed  ratifia  ;  as 
then  two  poifons  are  fwallowed  at  the  fame  time.  And  vine- 
gar, as  it  contains  much  vinous  fpirit,  is  probably  a  noxious  part 
of  our  diet.  And  the  diftilled  vinegar,  which  is  commonly  fold 
in  the  (hops,  is  truly  poifonous,  as  it  is  generally  diitilled  by 
means  of  a  pewter  or  leaden  alembic-head  or  worm-tube,  and 
abounds  with  lead  j  which  any  one  may  detect  by  mixing  with 
it  a  folution  of  liver  of  fulphur.  Opium,  when  taken  as  a  lux- 
ury, not  as  a  medicine,  is  as  pernicious  as  alcohol  ;  as  Baron 
de  Tott  relates  in  his  account  of  the  opium-eaters  in  Turkey. 

10.  It  muit  be  obferved,  that  a  frequent  repetition  of  the  ufe 
of  thisclafs  of  medicines  fo    habituates  the  body  to  their  ftimu- 
lus,  that  their  dofe  may  gradually  be  increafed  to  an  aftonifhing 
quantity,  fuch  as  otherwife  would  inltantly  deftroy  life  •,  as  is 
frequently  feen   in  thofe,  who  accuftom  themfelves  to  the  daily 
ufe  of  alcohol  and  opium  ;  and  it  would  feem,  that  thefe  unfor- 
tunate people  become  difeafed  as  foon  as  they  omit  their  ufual 
potations  -,  and  that  the  confequent  gout,  dropfy,  palfy,  or  pim- 
pled face,  occur  from  the  debility  occafioned  from  the  want  of 
accuftomed  ftimulus,  or  to  fome  change  in  the  contra^Hle  fi- 
bres, which  requires  the  continuance  or  increafe  of  it.     Whence 
the  cautions  neceflary  to  be  obferved  are  mentioned  in  Sect. 
XII.  7    8. 

11.  It  is  probable,  that  fome  of  the  articles  in  the  fubfequent 
catalogue   do  not  induce  intoxication,  though  they  have  been 
efteemed  to  do    fo  ;  as  tobacco,   hemlock,  nux  vomica,  ftavifa<- 
gria ;  and  on  this  account  (hould  rather  belong  to  other  arrange- 
ments, as  to  the  fecernentia,  or  forbentia,  or  invertentia. 

II.  i.  Externally  the  application  of  heat,  as  the  warmth  bath, 
by  its  ftimulus  on  the  fkin  excites  the  excretory  duds  of  the 
perfpirative  glands,and  the  mouths  of  the  lymphatics,  which  o- 
pen  on  its  furface,  into  greater  action ;  and  in  confequence  many 
other  irritative  motions,  which  are  aflbciated  with  them.  To 
this  increafed  action  is  added  pleafurable  fenfation,  which  a4ds 
further  a£Hvity  to  the  fyftem  j  and  thus  many  kinds  of  pain  re- 
ceive relief  from  this  additional  atmofphere  of  heat. 

The  ufe  of  a  warm  bath  of  about  96  or  98  degrees  of  heat, 
for  half  an  hour  once  a  day  for  three  or  four  months,  I  have., 

VOL.  I.  P  p  p  known 


24  INCITANTIA.  ART.  II.  2.  a.  i.- 

known  of  great  fenrice  to  weak  people,  and  is  perhaps  the  lead 
noxious  of  all  unnatural  ftimuli ;  which  however,  like  all  other 
great  excitement,  may  be  carried  to  excefs,  as  complained  of  by 
the  ancients.  The  unmeaning  application  of  the  words  relaxation 
and  bracing  to  warm  and  cold  baths  has  much  prevented  the 
ufe  of  this  grateful  flimulus  ;  and  the  mifufe  of  the  term  warm- 
bath,  when  applied  to  baths  colder  than  the  body,  as  to  thofe  of 
Buxton  and  Matlock,  and  to  artificial  baths  of  lefs  than  90  de- 
grees of  heat,  which  ought  to  be  termed  cold  ones,  has  contrib- 
uted to  miilead  the  unwary  in  their  application. 

The  ftimulusof  wine,  or  fpice,  or  fait,  increafes  the  heat  of 
the  fyflem  by  increafing  all  or  fome  of  the  fecretions  ;  and  hence 
the  ftrength  is  diminimed  afterwards  by  the  lofs  of  fluids,  as 
well  as  by  the  increafed  action  of  the  fibres.  But  the  llimulus 
of  the  warm  bath  fupplies  heat  rather  than  produces  it  ;  and 
rather  fills  the  fyftem  by  increafed  abforption,  than  empties  it 
by  increafed  fecretion  ;  and  may  hence  be  employed  with  advan* 
tage  in  almoft  all  cafes  of  debility  with  cold  extremities,  perhaps 
even  in  anafarca,  and  at  the  approach  of  death  in  fevers.  In 
thefe  cafes  a  bath  much  beneath  98  degrees,  as  of  80  or  85, 
might  do  injury,  as  being  a  cold  bath  compared  with  the  heat 
of  the  body,  though  fuch  a  bath  is  generally  called  a  warm  one. 

The  aftivity  of  the  fyftem  thus  produced  by  a  bath  of  98  de- 
grees of  heat,  or  upwards,  does  not  feem  to  render  the  patients 
liable  to  take  cold,  when  they  come  out  of  it  •,  for  the  fyftem  is 
lefs  inclined  to  become  torpid  than  before,  as  the  warmth  thus 
acquired  by  communication,  rather  than  by  increafed  action* 
continues  long  without  any  confequent  chilnefs.  Which  ac- 
cords with  the  obfervation  of  Dr.  Fordyce,  mentioned  in  Sup. 
I.  5.  r.  who  fays,  that  thofe  who  are  confined  fome  time  in  an 
atmofphere  of  120  or  130  degrees  of  heat,  do  not  feel  cold  or 
look  pale  on  coming  into  a  temperature  of  30  or  40  degrees  ; 
which  would  produce  great  palenefs  and  fenfation  of  coldnefs 
in  thofe,  who  had  been  fome  time  confined  in  an  atmofphere  of 
only  86  or  90  degrees  of  heat.  Treatife  on  Simple  Fever,  p. 
168. 

Hence  heat,  where  it  can  be  confined  on  a  torpid  part  along 
with  moifture,  as  on  a  fcrofulous  tamour,  will  contribute  to 
produce  fuppuration  or  refolution.  This  is  done  by  applying  a 
warm  poultice,  which  (hould  be  frequently  repeated  ;  or  a  plaf- 
terofrefm,  wax,  or  fat  ;  or  by  covering  the  part  with  oiled 
filk  •,  both  which  laft  prevent  the  perfpirable  matter  from  efcap- 
ing  as  well  as  the  heat  of  the  part,  as  thefe  fubftances  repel 
moifture,  and  are  bad  conductors  of  heat.  Another  great  ufe 
of  the  ftimulus  of  heat  is  by  applying  it  to  torpid  ulcers,  which 

are 


ART.  II.  2.  a.  i.  INCITANTIA.  25 

are  generally  termed  fcrofulous  or  fcorbutic,  and  are  much  eafier 
inclined  to  heal,  when  covered  with  feveral  folds  of  flannel. 

Mr. had  for  many  months  been  affiicled  with  an  ulcer 

in  perinaeo,  which  communicated  with  the  urethra,  through 
which  a  part  of  his  urine  was  daily  evacuated  with  confiderable 
pain  ;  and  was  reduced  to  a  great  degree  of  debility.  He  ufed 
a  hot-bath  of  96  or  98  degrees  of  heat  every  day  for  half  an 
hour  during  about  fix  months.  By  this  agreeable  ftimulus  re- 
peated thus  at  uniform  times  not  only  the  ulcer  healed,  contra- 
ry to  the  expectation  of  his  friends,  but  he  acquired  greater 
health  and  ftrength,  than  he  had  for  fome  years  previoufly  ex- 
perienced. 

Mrs. was  affected  with  tranfient  pains,  which  were  call- 
ed nervous  fpafms,  and  with  great  fear  of  difeafes  which  (he 
did  not  labour  under,  with  cold  extremities,  and  general  debil- 
ity. She  ufed  a  hot-bath  every  other  day  of  96  degrees  of  heat 
for  about  four  months,  and  recovered  a  good  (late  of  health, 
with  greater  ftrength  and  courage,  than  (he  had  pofleired  for 
many  months  before. 

Mr.  Z.  a  gentlemen  about  65  years  of  age,  had  lived  rather 
intemperately  in  refpect  to  vinous  potation,  and  had  for  many 
years  had  annual  vifits  of  the  gout,  which  now  became  irregu- 
lar, and  he  appeared  to  be  lofing  his  ftrength,  and  beginning  to 
feel  the  effects  of  'age.  He  ufed  a  bath,  as  hot  as  was  agreea- 
ble to  his  fenfations,  twice  a  week  for  about  a  year  and  half, 
and  greatly  recovered  his  health  and  ftrength  with  lefs  frequent 
and  lefs  violent  returns  of  regular  gout,  and  is  now  near  80  years 
of  age.  *  • 

When  Dr.  Franklin,  the  American  philofopher,  was  in  En- 
gland many  years  ago,  I  recommended  to  him  the  ufe  of  a 
warm-bath  twice  a  week  to  prevent  the  too  fpeedy  accefs  of  old 
age,  which  he  then  thought  that  he  felt  the  approach  of,  and  I 
have  been  informed,  that  he  continued  the  ufe  of  it  till  near  his 
death,  which  was  at  an  advanced  age. 

All  thefe  patients  were  advifed  not  to  keep  themfelves  warm- 
er than  their  ufual  habits  after  they  came  out  of  the  bath,  v/heth- 
.er  they  went  into  bed  or  not ;  as  the  defign  was  not  to  promote 
perfpiration,  which  weakens  all  conftitutions,  and  feldom  is  of 
fervice  to  any.  Thus  a  flannel  (hirt,  particularly  if  it  be  worn 
in  warm  weather,  occafions  weaknefs  by  ftimulating  the  (kin  by 
its  points  into  too  great  a&ion,  and  producing  heat  in  confe- 
quence  ;  and  occafions  emaciation  by  increafing  the  difcharge 
of  perfpirable  matter  ;  and  in  both  thefe  refpecls  differs  from 
the  efiect  of  warm  bathing,  which  communicates  heat  to  the 

fyftem 


26  INCITANTIA.  ART.  II.  a.  2.  c, 

fyftem  at  the  fame  time  that  it  ftimulates  it,  and  caufes  abforp- 
tion  more  than  exhalation. 

Thofe  who  have  remained  half  an  hour  in  a  warm  bath,  when 
they  have  previoufly  been  exhaufted  by  exercife,  or  abftinence 
from  food  or  fluids  have  abforbed  fo  much  as  to  increafe  their 
weight  confiderably.  Dr.  Jurin  found  an  increafe  of  weight  to 
1 8  ounces  by  deeping  in  a  cool  room  after  a  day's  exercife  and 
abftinence,  fo  much  in  that  fituation  was  abforbed  from  the  ar- 
mofphere.  But  it  has  lately  been  obferved  by  Dr.  Rollo  and  by 
Dr.  Currie,  that  fome  patients  did  not  weigh  heavier  after  com- 
ing out  of  the  warm  bath,  and  being  wiped  dry.  From  whence 
we  may  conclude,  that  thefe  patients  were  not  previoufly  in  a 
{late  of  inanition  ;  or  that  they  had  remained  fo  long  in  the 
bath  as  to  lofe  fomewhat  by  the  perpetual  wafte  of  the  fyftem 
by  digeftion,  circulation,  and  fecretion.  And  certainly  as  no 
-wafte  occurs  by  the  ufe  of  the  warm  bath,  this  muft  be  the  moft 
harmlefs,  confequently  the  moft  falutary  of  all  increafed  ftimuli. 
SceClafsI.  i.  2.  3. 

2.  The  effeft  of  the  pafTage  of  an  ele£tric  {hock  through  a 
paralytic  limb  in  caufing  it  to  contract,  befides  the  late  experi- 
ments of  Galvani  and  Volta  on  frogs,  entitle  it  to  be  clafled 
amongft  univerfal  ftimulants.  Ele&ric  {hocks  frequently  re- 
peated daily  for  a  week  or  two  remove  chronical  pains,  as  the 
pleurodyne  chronica,  Clafs  I,  2,  4,  14,  and  other  chronic  pains, 
which  are  termed  rheumatic,  probably  by  promoting  the  abiorp- 
tion  of  fome  extravafated  material.  Scrofulous  tumours  are 
fometimes  abforbed,  and  ibmetimes  brought  to  fuppurate  by  paf- 
(ing  eleclric  fhocks  through  them  daily  for  two  or  three  weeks, 

Mifs ,  a  young  lady  about  eight  years  of  age,  had  a 

fwelling  about  the  fize  of  a  pigeon's  egg  on  her  neck  a  little 
below  her  ear,  which  long  continued  in  an  indolent  ftate. 
Thirty  or  forty  fmall  eleclric  {hocks  were  palled  through  it  once 
or  twice  a  day  for  two  or  three  weeks,  and  it  then  fuppurated  and 
healed  without  difficulty.  For  this  operation  the  coated  jar  of 
the  ele£lvic  machine  had  on  its  top  an  electrometer,  which 
meafured  the  {hocks  by  the  approach  of  a  brafs  knob,  which 
communicated  with  the  external  coating  to  another,  which 
communicated  with  the  internal  one,  and  their  diftance  was  ad- 
jufted  by  a  fcrew.  So  that  the  {hocks  were  fo  fmall  as  not  to 
alarm  the  child,  and  the  accumulated  electricity  was  frequently 
difcharged  as  the  wheel  continued  turning.  The  tumour  was 
enclofed  between  two  other  brafs  knobs,  which  were  fixed  on 
wires,  which  pafled  through  glafs  tubes  ;  the  tubes  were  cement- 
ed in  t\vo  grooves  on  a  beard,  fo  that  at  one  end  they  were 

nearer 


ART.  II.  2.  3.  i.  INCITANTIA.  27 

nearer  each  other  than  at  the  other,  and  the  knobs  were  pufhed 
out  fo  far  as  exactly  to  include  the  tumour. 

•Inflammations  of  the  eyes  without  fever  are  frequently  cured 
by  taking  a  ftream  of  very  fmall  electric  fparks  from  them,  or 
giving  the  electric  fparks  to  them,  once  or  twice  a  day  for  a 
week  or  two  ;  that  is,  the  new  veffels,  which  conftitute  inflam- 
mation in  thefe  inirritable  conilitutions,  are  abforbed  by  the  ac- 
tivity of  the  abforbents  induced  by  the  flimulus  of  the  electric 
aura.  For  this  operation  the  eafieft  method  is  to  fix  a  pointed 
wire  to  a  flick  of  iealing  wax,  or  to  an  infulating  handle  of  glafs? 
one  end  of  this  wire  communicates  with  the  prime  conductor, 
and  the  point  is  approached  near  the  inflamed  eye  in  every  di- 
rection. 

III.  Externally  the  application  of  ether,  and  of  efiential  oils, 
as  of  cloves  or  cinnamon,  feems  to  poflefs  a  general  flimulating 
effect.       As    they    inftantly  relieve  tooth-ach,  and  hiccough, 
when   thefe  pains    are  not  in  violent  degree- ;  and  camphor  in 
large  dofes  is  laid  to  produce  intoxication  ;  this  effect  however 
I  have  not  been  witnefs  to,  and  have  reafon  to  doubt. 

Ether  dropped  into  the  ears  of  fome  deafifh  people,  feems  to 
poflefs  a  two-fold  effect,  one  of  diflblving  the  indurated  ear-wax, 
and  the  other  of  flimulating  the  torpid  organ,  but  it  is  liable  to 
give  fome  degree  of  pain,  unlefs  it  be  freed  from  the  fulphurous 
acid,  fome  of  which  arifes  along  with  it  in  diitillation  ;  to  pu- 
rify it  from  this  material  it  fhould  be  rectified  from  manganefe. 
See  Clafs  I.  2.  5.  6.  Lime  added  to  impure  ether  may  alfo 
unite  with  the  fulphuric  acid,  if  fuch  exilts  in  it,  and  form  fele* 
nite,  and  fubfide. 

The  manner  in  which  ether  and  the  efTentlal  oil  operate  on 
the  fyflem  when  applied  externally,  is  a  curious  queftion,  as 
pain  is  fo  immediately  relieved  by  them,  that  they  mud  feem  to 
penetrate  by  the  great  fluidity  or  expanfive  property  of  a  part  of 
them,  as  of  their  odoriferous  exhalationor  vapour,  and  thus  ftim- 
ulate  the  torpid  part,  and  not  by  their  being  taken  up  by  the  ab- 
forbent  veffels,  and  carried  thither  by  the  long  courfe  of  circula- 
tion •,  nor  is  it  probable,  that  thefe  pains  are  relieved  by  the 
fympathy  of  the  torpid  membrane  with  the  external  (kin,  which 
is  thus  flimulated  into  action  ;  as  it  does  not  fucceed,  unlefs  it 
is  applied  over  the  pained  part.  Thus  there  appears  to  be  three 
different  modes  by  which  extraneous  bodies  may  be  introduced 
into  the  fyflem,  befides  that  of  abforption.  ift.  By  ethereal 
tranfition,  as  heat  and  electricity  ;  2d.  by  chemical  attraction, 
as  oxygen  ;  and  3d.  by  expanfive  vapour,  as  ether  and  eiienV 
*ial  oils. 

IV.  The  perpetual  neceffity  of  the  mixture  of  oxygen  gas 

with 


28  INCITANTTA.  ART.  II.  2. 4.  r. 

with  the  blood  in  the  lungs  evinces,  that  it  muft  act  as  a  ftimu- 
lus  to  the  fanguiferous  fyftem,  as  the  motions  of  the  heart  and 
arteries  prefently  ceafe,  when  animals  are  immerfed  in  airs 
which  pofTefs  no  oxygen.  It  may  alfo  fubfequently  anfwer 
another  important  purpofe,  a"s  it  is  probable  that  it  affords  the 
material  for  the  production  of  the  fenforial  power ;  which  is 
fuppofed  to  be  fecreted  in  the  brain  or  medullary  part  of  the 
nerves  ;  and  that  the  perpetual  demand  of  this  fluid  in  refpira- 
tion  is  occafioned  by  the  fenforial  power,  which  is  fuppofed  to 
4be  produced  from  it,  being  too  fubtle  to  be  long  confined  in  any 
part  of  the  .yftem. 

Another  proof  of  the  ftimulant  quality  of  oxygen  appears 
from  the  increafed  acrimony,  which  the  matter  of  a  common 
abfcefs  pofiefles,  after  it  has  been  expofed  to  the  air  of  the  at- 
mofphere,  but  not  before  ;  and  probably  all  other  contagious 
'matters  owe  their  fever- producing  property  to  having  been  con- 
verted into  acids  by  their  union  with  oxygen.  See  Clafs  II.  i.  8. 

As  oxygen  penetrates  the  fine  moid  membranes  of  the  air-vef- 
fels  of  the  lungs,  and  unites  with  the  blood  by  a  chemical  at- 
traction, as  is  feen  to  happen,  when  blood  is  drawn  into  a  bafon, 
the  lower  furface  of  the  crafiamentum  is  of  a  very  dark  red  fo 
long  as  it  is  covered  from  the  air  by  the  upper  furface,  but  be- 
comes florid  in  a  ihort  time  on  its  being  expofed  to  the  atmof- 
phere  ;  the  manner  of  its  introduction  into  the  fyftem  is  not 
probably  by  animal  abforption  but  by  chemical  attraction,  in 
which  circumftance  it  differs  from  the  fluids  before  mentioned 
both  of  heat  and  electricity,  and  of  ether  and  efTential  oils. 

As  oxygen  has  the  property  of  pafTmg  through  moift  animal 
jnembranes,  as  firft  difcovered  by  the  great  Dr.  Prieftley,  it  is 
probable  it  might  be  of  ufe  in  vibices,  and  petechise  in  fevers, 
and  in  other  bruifes  ;  if  the  ikin  over  thofe  parts  was  kept  moift 
by  warm  water,  and  covered  with  oxygen  gas  by  means  of  an 
inverted  glafs,  or  even  by  expofing  the  parts  thus  moiftened  to 
the  atmofphere,  as  the  dark  coloured  extravafated  blood  might 
thus  become  florid,  and  by  its  increafe  of  ftimulus  facilitate  its 
reabforption. 

Two  weak  parients,  to  whom  I  gave  oxygen  gas  in  as  pure  a 
Hate  as  it  can  eafily  be  produced  from  Exeter  manganefe,  and 
in  the  quantity  of  about  four  gallons  a  day,  feemed  to  feel  re- 
freihed,  and  ftronger,  and  to  look  better  immediately  after  ref- 
piring  it,  and  gained  ftrength  in  a  fhort  time.  Two  others, 
one  of  whom  laboured  under  confirmed  hydrothorax,  and  the 
other  under  a  permanent  and  uniform  difficulty  of  refpiration, 
were  not  refreshed,  or  in  any  way  ferved  by  the  ufe  of  oxygen  in 
the  above  quantity  of  four  gallons  a  day  for  a  fortnight,  which 


ART.  II.  2.  5.  i.  INCITANTIA.  29 

I  afcribed  to  the  inirritability  of  the  difeafed  lungs.  For  other 
cafes  the  reader  is  referred  to  the  publications  of  Dr.  Beddoes  ; 
Confiderations  on  the  Ufe  of  Factitious  Airs,  fold  by  Johnfon, 
London. 

Irs  effects  would  probably  have  been  greater  in  refpedt  to  the 
quantity  breathed,  if  it  had  been  given  in  a  dilute  (late,  mixed 
with  10  or  20  times  its  quantity  of  atmofpheric  air,  as  otherwife 
much  of  it  returns  by  expiration  without  being  deprived  of  its 
quality,  as  may  be  feen  by  the  perfon  breathing  on  the  flame  of 
a  candle,  which  it  enlarges.  See  the  Treatife  of  Dr.  Beddoes 
above  mentioned. 

Mr.  Scott  in  his  letters  in  the  Bombay  Courier  gave  the  black 
calciform  ore  of  manganefe  in  the  quantity,  he  fays,  of  feverai 
drachms  a  day  without  any  inconvenience  to  a  venereal  patient, 
hoping  to  ferve  him  by  the  oxygen  contained  in  that  calx.  I 
have  formerly  given  lapis  calaminaris  to  the  quantity  of  20 
grains  twice  a  day  in  confumption,  without  inconvenience,  and  I 
fuppofe  this  calciform  ore  of  zinc,  as  well  as  the  rufl  of  iron, 
may  be  an  union  of  thofe  metals  with  oxygen,  and  may  probably 
be  given  internally  with  more  fafety  than  calces  of  lead,  which 
were  once  famous  in  confumptions.  See  Clafs  II.  i.  5,  2.  and 
Article  IV.  2.  7.  i. 

V.  Thofe  paflions,  which  are  attended  with  pleafurable  fenfa- 
tion,  excite  the  fyftem  into   increafed  action  in  confequence  of 
that  fenfation,  as  joy,  and  love,  as  is  feen  by  the  flufli  of  the  fkin. 
Thofe  paflions,   which  are  attended  with  difagreeable  fenfation, 
produce  torpor  in  general  by  the  expenfe  of  fenforial  power  oc- 
cafioned  by  inactive  pain  ;    unlefs  volition  be  excited  in  confe- 
quence of  the  painful  fenfation  ;  and  in  that  cafe  an  increafed 
activity  of  the  fyftem  occurs  ;  thus  palenefs  and  coldnefs  are  the 
confequence  of  fear,    but  warmth  and   redncfs  are  the  confe- 
quence of  anger. 

VI.  Befides  the  exertions  of  the  fyftem  occafioned  by  increaf- 
ed ftimuli,  and  confequent  irritation,  and  by  the  paflions  of  the 
mind  above  defcribed,  the  increafed  actions  occafioned  byexer- 
cife  belong  to  this  article.     Thefe  may  be  divided  into  the  ac- 
tions of  the  body  in  confequence  of  volition,  which  is  generally 
termed  labour  ;  or  fecondly,  in  confequence  of  agreeable  fenfa- 
tion, which  is  termed  play  or  fport ;  thirdly,  the  exercife  occa- 
fioned by  agitation,  as  in  a  carriage  or  on  horfeback  ;  fourthly, 
that  of  friction,  as   with    a  brufh  or  hand,  fo  much  ufed  in  the 
baths  of  Turkey  ;  and  laftly,  the  exercife  of  fwinging. 

The  firft  of  thefe  modes  of  exercife  is  frequently  carried  to 
great  excefs  even  amongft  our  own  labourers,  and  more  fo  un- 
der the  lam  of  flavery ;  fo  that  the  body  becomes  emaciated  and 

finks 


30  INCITANTIA,  ART.  II.  2, 6.  i. 

finks  under  either  the  prefent  hardfhips,  or  by  a  premature  old 
age.  The  fecond  mode  of  exercife  is  feen  in  the  play  of  all 
young  animals,  as  kittens,  and  puppies,  and  children  ;  and  is  fo 
neceilary  to  their  health  as  well  as  to  their  pleafure,  that  thofe 
children,  which  are  too  much  confined  from  it,  not  only  become 
pale-faced  and  bloated,  with  tumid  bellies,  and  confequent 
worms,  but  are  liable  to  get  habits  of  unnatural  actions,  as 
twitching  of  their  limbs,  or  fome  parts  of  their  countenance  ; 
together  with  an  ill-humoured  or  difcontented  mind. 

Agitation  in  a  carnage  or  on  horfeback,  as  it  requires  fome 
little  voluntaty  exertion  to  preferve  the  body  perpendicular,  but 
much  lefs  voluntary  exertion  than  in  walking,  feems  the  bcft 
adapted  to  invalids  ;  who  by  thefe  means  obtain  exercife  prin- 
cipally by  the  ftrength  of  the  horfe,  and  do  not  therefore  too 
much  exhauft  their  own  fenforial  power.  The  ufe  of  fricYion 
with  a  bru(h  or  hand,  for  half  an  hour  or  longer  morning  and 
evening,  is  (till  better  adapted  to  thofe,  who  are  reduced  to  ex- 
treme debility  ;  arid  none  of  their  own  fenforial  power  is  thus 
expended,  and  affords  fomewhat  like  the  warm  bath  activity 
without  felf-exertion,  and  is  ufed  as  a  luxury  after  warm  bathing 
in  many  parts  of  Afia. 

Another  kind  of  exercife  is  that  of  fwinging,  which  requires 
fome  exertion  to  keep  the  body  perpendicular,  or  pointing  to- 
wards the  centre  of  the  fwing,  but  is  at  the  fame  time  attended 
with  a  degree  of  vertigo  ;  and  is  defcribed  in  Ciafs  II.  1.6.  7. 
IV.  2.  r.  lo.Sup.  I,  3.  and  15. 

The  neceflity  of  much  exercife  has  perhaps  been  more  infifted 
upon  by  phyficians,  than  nature  feems  to  demand.  Few  ani- 
mals exercife  themfelves  fo  as  to  induce  vifible  fweat,  unlefs  urg- 
ed to  it  by  mankind,  or  by  fear,  or  hunger.  And  numbers  of 
people  in  our  market  towns,  of  ladies  particularly,  with  fmali 
fortunes,  live  to  old  age  in  health,  without  any  kind  of  exercife 
of  body,  or  much  activity  of  mind. 

In  fummer  weak  people  cannot  continue  too  long  in  the  air,  if 
it  can  be  done  without  fatigue  ;  and  in  winter  they  (hould  go 
out  feveral  times  in  a  day  for  a  few  minutes,  ufmg  the  cold  air 
like  a  cold-bath,  to  invigorate  and  render  them  more  hardy. 

III.  CATALOGUE   OF  THE  INCITANTIA. 

I.  Papaver  fomniferum  ;    poppy,  opium. 
Alcohol,  wine,  beer,  cider. 

Prunus  lauro-cerafus;  laurel,  diftilled  water  from  the  leaves* 
Prunus  cerafus  5    black  cherry,  diftilled    water  from    the 
kernels. 

Njcotiana 


AAT.  III.  i.  i.  SECERNENTIA.  31 

Nicotiana  tabacum  ;  tobacco  ;    the  eflential  oil,  deco£lion 

of  the  leaf. 

Atropa  belladonna  ;  deadly  nightfhade,  the  berries. 
Darura  ftramoneum  ;  thorn- apple,  the  fruit  boiled  in  milk. 
Hyofcyamus  reticulatus  ;  henbane,  the  feeds  and  leaves. 
Cynogloflum  j  hounds  tongue. 
Menifpermum,  cocculus  ;  Indian  berry. 
Amygdalus  amarus  ;   bitter  almond. 
Cicuta  ;  hemlock.      Conium  maculatum  ? 
Strychnos  nux  vomica  ? 
Delphinium  ftavifagria  ? 
II.  Externally,  heat,  electricity. 

III.  Ether,  eflential  oils. 

IV.  Oxygen  gas. 

V  PafTions  of  love,  joy,  anger. 
VI.  Labour,  play,  agitation,  friction. 


ART.  III. 
SECERNENTIA. 

I  THOSE  THINGS  which  increafe  the  irritative  motions,  which 
conftitute  fecretion,  are  termed  fecernentia ;  which  are  as  vari- 
ous as  the  glands,  which  they  ftimulate  into  action. 

1.  Diaphoretics,  as  aromatic  vegetables,  eflential  oils,  ether, 
volatile  alkali,  neutral  falts,  antimonial  preparations,    external 
heat,  exercife,  friction,  cold  water  for  a  time  with  fubfequent 
warmth,  blifters,  electric  fluid. 

2.  Sialagogues,  as  mercury  internally,  and  pyrethrum  exter- 
nally. 

3'  Expectorants,  as  fquill,  onions,  gum  ammoniac,  feneka 
root,  mucilage  :  fome  of  thefe  increaie  the  pulmonary  peripira-, 
tion,  and  perhaps  the  pulmonary  mucus. 

4.  Diuretics,  as  neutral  falts,  fixed  alkali,  balfams,  reflns,  af- 
paragus,  cantharides. 

3.  Cathartics  of  the  mild  kind,  as  fenna,  jalap,  neutral  falts, 
manna,     'i  hey  increafe  the  fecretions  of  bile,  pancreatic  juice, 
and  inteftinal  mucus. 

6.  The  mucus  of  the  bladder  is  increafed  by  cantharides,  and 
perhaps  by  oil  of  turpentine. 

'VOL,  I. 


32  SECERNENT! A.        ART.  HI.  1.1.7. 

7.  The  mucus  of  the  re£lum  by  aloe  internally,  by  clyfters 
and  fuppofitories  externally. 

8  The  mucus  of  the  cellular  membrane  is  increafed  by  blif- 
ters  and  (inapifms, 

9.  The  mucus  of  the  noftrils  is  increafed  by  errhines  of  the 
milder  kind,  as  marum,  common  fnuff. 

10.  The  fecretion  of  tears  is  increafed  by  volatile  falts,  the 
vapour  of  onions,  by  grief,   and  joy. 

if.  All  thofe  medicines  increafe  the  heat  of  the  body,  and 
remove  thofe  pains,  which  originate  from  a  defeft  of  motion  in 
the  veflels,  which  perform  fecretion  ;  as  pepper  produces  a  glow 
on  the  fkin,  and  balfam  of  Peru  is  faid  to  relieve  the  flatulent 
colic.  But  thefe  medicines  differ  from  the  preceding  clafs,  as 
they  neither  induce  coftivenefs  nor  deep  coloured  urine  in  their 
ufual  dofe,  nor  intoxication  in  any  dofe. 

12.  Yet  if  any  of  thefe  are  ufed  unneceflarily,  it  is  obvious, 
like  the  incitantia,  that  they  muft  contribute  to  (horten  our  lives 
by  fooner  rendering  peculiar  parts  of  the  fyftem  difobedient  to 
their  natural  (timuli.  Of  thofe  in  daily  ufe  the  great  excefs  of 
common  fait  is  probably  the  moft  pernicious,  as  it  enters  all  our 
cookery,  and  is  probably  one  caufe  of  fcrofula,  and  of  fea-fcur- 
vy,  when  joined  with  other  caufes  of  debility  See  Botanic 
Garden,  Part  II.  Canto  IV.  line  221.  Spices  taken  to  excefs 
by  ftimulating  the  ftomach,  and  the  veflels  of  the  fkin  by  aflbci- 
ation,  into  unneceflary  aftion,  contribute  to  weaken  thefe  parts 
of  the  fyftem,  but  are  probably  lefs  noxious  than  the  general  ufe 
of  fo  much  fait. 

II.  OBSERVATIONS  ON  THE  SECERNENTIA. 

I.  i.  Some  of  the  medicines  of  this  clafs  produce  abforption 
in  fome  degree,  though  their  principal  effeft  is  exerted  on  the 
fecerning  part  of  our  fyftem.  We  (hall  have  occafion  to  ob- 
ferve  a  fimilar  circumftance  in  the  next  clafs  of  medicines  term- 
ed Sorbentia  ;  as  of  thefe  fome  exert  their  effects  in  a  fmaller 
degree  on  the  fecerning  fyftem.  Nor  will  this  furprife  any  one, 
who  has  obferved,  that  all  natural  objefts  are  prefented  to  us 
in  a  ftate  of  combination ;  and  that  hence  the  materials,  which 
produce  thefe  different  effects,  are  frequently  found  mingled  in 
the  fame  vegetable.  Thus  the  pure  aromarics  increafe  the  ac- 
tion of  the  veflels,  which  fecrete  the  perfpirable  matter ;  and 
the  pure  aftringents  increafe  the  aftion  of  the  veflels,  which  ab- 
forb  the  mucus  from  the  lungs,  and  other  cavities  of  the  body  ; 
hence  it  muft  happen,  that  nutmeg,  which  pofiefles  both  thefe 
qualities!  fliould  have  the  double  effeft  above  mentioned. 

Other 


ART.  III.  2.1.2.         SECERNENTIA.  33 

Other  drugs  have  this  double  effect,  and  belong  either  to  the 
clafs  of  Secernentia  or  Sorbentia,  according  to  the  dofe  in  which 
they  are  exhibited.  Thus  a  fmall  dofe  of  alum  increafes  ab- 
forption,  and  induces  coftivenefs  -,  and  a  large  one  increafes  the 
fecretions  into  the  inteftinal  canal,  and  becomes  cathartic.  And 
this  accounts  for  the  conftipation  of  the  belly  left  after  the  pur- 
gative quality  of  rhubarb  ceafes,  for  it  increafes  abforption  in 
a  fmaller  dofe,  and  fecretion  in  a  greater.  Hence  when  a  part 
of  a  larger  dofe  is  carried  out  of  the  habit  by  ftools,  the  fmall 
quantity  which  remains  induces  coftivenefs.  Hence  rhubarb 
exhibited  in  fmall  dofes,  as  two  or  three  grains  twice  a  day, 
ftrengthens  the  fyftem  by  increafing  the  adtion  of  the  abforbent 
veflels,  and  of  the  inteftinal  canal. 

2.  Diaphoretics.     The  perfpiration  is  a  fecretion  from  the 
blood  in  its  paflage  through  the  capillary  veflels,   as  other  fecre- 
tions are  produced  in  the  termination  of  the  arteries  in  the   va- 
rious glands.     After  this    fecretion    the  blood  lofes  its   florid 
colour,  which  it  regains  in  its  paflage  through  the  lungs ;  which 
evinces  that  fomething  befides  water  is  fecreted  on  the  {kins  of 
animals. 

No  ftatical  experiments  can  afcertain  the  quantity  of  our  per- 
fpiration ;  as  a  continued  abforption  of  the  moifture  of  the  at- 
mofphere  exifts  at  the  fame  time  both  by  the  cutaneous  and  pul- 
monary lymphatic. 

3.  Every  gland  is  capable  of  being  excited  into  greater  exer- 
tions by  an  appropriated  ftimulus  applied  either  by  its  mixture 
with  the  blood  immediately  to  the  fecerning  veflei,  or  applied 
externally  to  its  excretory  duel:.     Thus  mercury  internally  pro- 
motes an  increafed  falivation,  and  pyrethrum  externally  applied 
to  the  excretory  ducts  of  the  falival  glands.     Aloes  ftimulate 
the  rectum  internally  mixed  with  the  circulating  blood  ;    and 
fea-falt  by  injection  externally.     Now  as  the  capillaries,  which 
fecrete  the  perfpirable  matter,  lie  near  the  furface  of  the  body, 
the  application  of  external  heat  acts  immediately  on  their  excre- 
tory ducts,  and  promotes  perfpiration  \    internally  thofe  drugs 
which  poflefs  a  fragant  eflential  oil,  or  fpiritus  rector,  produce 
this  effe6t,  as  the  aromatic  vegetables,  of  which  the  number  is 
very  great. 

4.  It  muft  be  remembered,  that   a   due  quantity  of  fome 
aqueous  vehicle  muft  be  given  to  fupport  this  evacuation  ;  oth- 
erwife  a  burning  heat  without  much   vifible  fweat  muft  be  the 
confequence.     When  the  fkin  acquires  a  degree  of  heat  much 
above  1 08,  as  appears  by  Dr.   Alexander's  experiments,  no  vifi- 
ble fweat  is  produced  ;  which  is  owing  to  the  great  heat  of  the 
fkin  evaporating  it  as  haftily,  as  it  is  fecreted  ;  and,  where  the 

fweat 


34  SECERNENTIA.  ART.  IH.  2.  i.  5. 

fweat  is  fecreted  in  abundance,  its  evaporation  cannot  carry  off 
the  exuberant  heat,  like  the  vapour  of  boiling  water  ;  becaufe  a 
great  part  of  it  is  wiped  off,  or  abforbed  by  the  bed-clothes  ;  or 
the  air  about  the  patient  is  not  changed  fufficiently  often,  as  it 
becomes  faturated  with  the  perfpirable  matter.  And  hence  it 
is  probable,  that'the  wafte  of  perfpirable  matter  is  as  great,  or 
greater,  when  the  (kin  is  hot  and  dry,  as  when  it  (lands  in 
drops  on  the  fkin  ;  as  appears  from  the  inextinguifhable 
third 

Hence  Dr.  Alexander  found,  that  when  the  heat  of  the  body 
was  greater  than  1 08,  nothing  produced  fweats  but  repeated 
draughts  of  cold  water  ;  and  of  warm  fluids,  when  the  heat 
was  much  below  that  degree.  And  that  cold  water  which  pro- 
cured fweats  inftantaneoufly  when  the  heat  was  above  108, 
flopped  them  as  certainly  when  it  was  below  that  heat ;  and 
thar  flannels,  wrung  out  of  warm  water  and  wrapped  round  the 
legs  and  thighs,  were  then  moil  certainly  productive  of  fweats. 

5  The  diaphoretics  are  all  faid  to  fucceed  much  better,  if  given 
early  in  the  morning,  about  an  hour  before  fun-rife,  than  at  any 
other  time  ;  which  is  owing  to  the  great  excitability  of  every 
part  of  the  fyflem  after  the  fenforial  power  has  been  accumu- 
lated during  fleep.  In  thofe,  who  have  heftic  fever,  or  the  fe- 
bricula,  or  nocturnal  fever  of  debility,  the  morning  fwears  are 
owing  to  the  decline  of  the  fever-fit,  as  explained  in  Se£l. XXXII. 
p  In  fome  of  thefe  patients  the  fweat  does  not  occur  till  they 
awake  j  becaufe  then  the  fyftem  is  ftill  more  excitable  than  du- 
ring fleep,  becaufe  the  afliftance  of  the  voluntary  power  in 
refpiration  facilitates  the  general  circulation.  See  Clafs  I. 
2.  I.  3. 

6.  It  muft  be  obferved,  that  the  fkin  is  very  dry  and  hard 
to  the  touch,  where  the  abforbents,  which  open  on  its  furface,  do 
not  aft  ;  as  in  fome  dropfies,   and  other  difeafes  attended  with 
great  thir ft.  This  drynefs,  and  fhrivelled  appearance,  and  rough- 
nefs,  are  owing  to  the  mouths  of  the  abforbents  being  empty  of 
their  accuftomed  fluid,  and   is  diftinguifhabie  from  the  drynefs 
of  the  fkin  above  mentioned  in  the  hot  fits  of  fever,   by  its  not 
being  attended  with  heat. 

As  the  heat  of  the  fkin  in  the  ufual  temperature  of  the  air 
always  evinces  an  increafed  perfpiration,  whether  vifible  or  not, 
the  heat  being  produced  along  with  the  increafe  of  fecretion  ; 
it  follows,  that  a  defeft  of  perfpiration  can  only  exift,  when  the 
fkin  is  cold. 

7.  Volatile  alkali  is  a  very  powerful  diaphoretic,  and  partic- 
ularly  if  exhibited  in  wine- whey  \    twenty   drops  of    fpirit  of 
hartihorn  every  half  hour  in  half  a  pint  of  wine- whey,  if  the  pa- 
tient 


ART.  II.  2.  i.  8.  SECERNENTIA.  35 

tient  be  kept  in  a  moderate  warm  bed,  will  in    a    few  hours 
elicit  moft  profufe  fweats. 

N.utral  falts  promote  invifible  perfpiration,  when  the  ikin  is 
not  warmed  much  externally,  as  is  evinced  from  the  great  third, 
which  fucceeds  a  meal  of  fait  provifions,  as  of  red  herrings. 
When  thefe  are  fufficiently  diluted  with  water,  and  the  (kin 
kept  warm,  copious  fweats  without  inflaming  the  habit,  are  the 
cor.fequence.  Half  an  ounce  of  vinegar  faturated  with  volatile 
alkali,  taken  every  hour  or  two  hours,  well  anfwers  this  pur- 
pole  j  and  is  preferable  perhaps  in  general  to  all  others,  where 
{wearing  is  advantageous.  Boerhaave  mentions  one  cured  of 
a  fever  by  eating  red -herrings  or  anchovies,  which,  with  repeat- 
ed draughts  of  warm  water  or  tea,  would  I  fuppofe  produce  co- 
pious perfpiration. 

Antimonial  preparations  have  alfo  been  of  late  much  ufed 
with  great  advantage  as  diaphoretics.  For  the  hiftory  and  ufe 
of  thele  preparations  I  fhal<  refer  the  reader  to  the  late  writers 
on  the  Materia  Medica,  only  obferving  that  the  ftomach  be- 
comes fo  foon  habituated  to  its  (limulus,  that  the  fecond  dole 
may  be  confiderably  increafed,  if  the  firft  had  no  operation. 

Where  it  is  advifable  to  procure  copious  fweats,  the  emetics, 
as  ipecacuanha,  joined  with  opiates,  as  in  Dover's  powder,  pro- 
duce this  effect  with  greater  certainty  than  the  above. 

8.  We  mud  not  difmifs  this  fubjecT:  without  obferving,  that 
perfpiration  is  defigned  to  keep  the  (kin  flexible,  as  the  tears  are 
intended  to  clean  and  lubricate  the  eye  ;  and  that  neither  of 
thefe  fluids  can  be  confidered  as  excretions  in  their  natural  ftnte, 
but  as  fecretions.  See  Clafs  I.  1.2.  3.  And  that  therefore 
the  principal  ufe  of  diaphoretic  medicines  is  to  warm  the  (kin, 
and  thence  in  confequence  to  produce  the  natural  degree  of  in- 
fenfible  perfpiration  in  languid  habits. 

y.  When  the  ikin  of  the  extremities  is  cold,  which  is  always 
a  fign  of  prefent  debility,  the  digeftion  becomes  frequently  im- 
paired by  aflbciation,  and  cardialgia  or  heartburn  is  induced 
from  the  vinous  or  acetous  fermentation  of  the  aliment.  In  this 
difeafe  diaphoretics,  which  have  been  called  cordials,  by  their 
aclionon  the  ftomach  reftore  its  exertion,  and  that  of  the  cu- 
taneous capillaries  by  their  aflbciation  with  it,  and  the  (kin  be- 
comes warm,  and  the  digeftion  more  vigorous. 

10.  But  a  blifter  acls  with  more  permanent  and  certain  ef- 
feel  by  ftimulating  a  part  of  the  ikin,  and  thence  aftecling  the 
whole  of  it,  and  of  the  ftomach  by  aflbciation,  and  thence  re- 
moves the  moft  obftinate  heartburns  and  vomitings.  From 
this  the  principal  ufe  of  blifters  is  underftood,  which  is  to  in- 
vigorate the  exertions  of  the  arterial  and  lymphatic  veflels  of  the 

ikin, 


36  SECERNENTIA.  ART.  III.  2. 2.  *. 

(kin,  producing  an  increafe  of  infenfible  perfpiration,  and  of  cu- 
taneous abforption  ;  and  to  increafe  the  aftion  of  the  ftomach, 
and  the  confequent  power  of  digeftion  ;  and  thence  by  fympa- 
thy  to  excite  all  the  other  irritative  motions  :  hence  they  relieve 
pains  of  the  cold  kind,  which  originate  from  defect  of  motion  ; 
not  from  their  introducing  a  greater  pain,  as  fome  have  imagin- 
ed, but  by  ftimulating  the  torpid  veflels  into  their  ufual  action  ; 
and  thence  increafing  the  action  and  confequent  warmth  of  the 
whole  fkin,  and  of  all  the  parts  which  are  aflbciated  with  it. 

II.  i.    Sia/agogues.     The  preparations  of  mercury  confift  of 
a  folution  or  corrofion  of  that  metal  by  fome  acid  ;    and,  when 
the  dofe  is  known,  it  is  probable  that  they  are  all  equally  effi- 
cacious.    As  their  principal  ufe  is  in  the  cure  of  the  venereal  dif- 
eafe,  they  will  be  mentioned  in  the  catalogue  amongft  the  for- 
bentia.     Where  falivation  is  intended,  it  is  much  forwarded  by 
a  warm  room  and  warm  clothes  ;  and  prevented  by  expofing 
the  patient  to  his  ufual  habits  of  cool  air  and  drefs,  as  the  mer- 
cury is  then  more  liable  to  go  off  by  the  bowels. 

2.  Any  acrid  drug,  as  pyrethrum,  held  in  the  mouth  acts  as 
a  fialagogue  externally  by  ftimulating  the  excretory  duels  of  the 
falivary  glands ;  and  the  filiqua  hirfuta  applied  externally  to  the 
parotid  gland,  and  even  hard  fubftances,   in  the  ear,  are  faid  to 
have  the  fame  effect.     Maftich  chewed   in  the  mouth  emulges 
the  falivary  glands. 

3.  The  unwife  cuftom  of  chewing  and  fmoking  tobacco  for 
niany  hours  in  a  day  not  only  injures  the  falivary  glands,   pro- 
ducing drynefs  in  the  mouth  when  this  drug  is  not  ufed,  but  I 
fufpeft  thaf  it  alfo  produces  fcirrhus  of  the  pancreas.     The  ufe 
of  tobacco  in  this  immoderate  degree  injures  the  power   of  di- 
geftion, by  occafioning  the  patient  to  fpit  out  that  faliva,  which 
he  ought  to  fwallow  ;  and  hence  produces  that  flatulency,  which 
the  vulgar  unfortunately  take  it  to  prevent.     The  mucus,  which 
is  brought  from  the  fauces  by  hawking,   fliould  be  fpit  out,  as 
well  as  that  coughed  up  from  the  lungs  ;    but  that  which  comes 
fpontaneoufly  into  the   mouth  from  the  falivary  glands,  fhould 
be  fwallowed  mixed  with  our  food  or  alone  for  the  purpofes-of 
digeftion.     See  Ciafsl.  2.  2.  7. 

III.  i.  Expeftorants  are  fuppofed  to  increafe  the  fecretion 
of  mucus  in  the  branches  of   the  windpipe,  or  to  increafe  the 
perfpiration  of  the  lungs  fecreted  at  the  terminations  of  the  bron- 
chial artery. 

2.  If  any  thing  promotes  expectoration  toward  the  end  of 
peripneumonies,  when  the  inflammation  is  reduced  by  bleeding 
and  gentle  cathartics,  frnall  repeated  blifters  about  the  cheft, 
with  tepid  aqueous  and  mucilaginous  or  oily  liquids,  are  more 

advantageous 


ART.  III.  2. 3.  3.          SECERNENTIA.  3^ 

advantageous  than  the  medicines  generally  enumerated  under 
this  head  ;  the  blifters  by  ftimulating  into  aftion  the  vefTels  of 
the  fkin  produce  by  aflbciation  a  greater  activity  of  thofe  of 
the  mucous  membrane,  which  lines  the  branches  of  the  wind- 
pipe, and  air-cells  of  the  lungs  -,  and  thus  after  evacuation  they 
promote  the  abforption  of  the  mucus  and  confequent  healing  of 
the  inflamed  membrane,  while  the  diluting  liquids  prevent  this 
mucus  from  becoming  too  vifcid  for  this  purpofe>  or  facilitate 
its  expuition. 

Blifters,  one  at  a  time,  on  the  fides  or  back,  or  on  the  fter- 
num,  are  alfo  ufeful  towards  the  end  of  peripneumonies,  by  pre- 
venting the  evening  accefs  of  cold  fit,  and  thence  preventing 
the  hot  fit  by  their  ftimulus  on  the  fkin  ;  in  the  fame  manner 
as  five  drops  of  laudanum  by  its  ftimulus  on  the  ftomach.  For 
the  increased  actions  of  the  veflels  of  the  fkin  or  ftomach  excite 
a  greater  quantity  of  the  fenforial  power  of  affociation,  and  thus 
prevent  the  torpor  of  the  other  parts  of  the  fyftem  ;  which, 
when  patients  are  debilitated,  is  fo  liable  to  return  in  the 
evening. 

3.  Warm  bathing  is  of  great  fervice  towards  the  end  of  perip- 
neumony  to  promote  expecl oration,  efpecially  in  thofe  children 
who  drink  too  little  aqueous  fluids,  as  it  gently  increafes  the 
aftion  of  the  pulmonary  capillaries  by  their  confent  with  the 
cutaneous  ones,  and  fupplies  the  fyftem  with  aqueous  fluid,  and 
thus  dilutes  the  fecreted  mucus. 

Some  have  recommended  oil  externally  around  the  cheft,  as 
well  as  internally,  to  promote  expectoration  ;  and  upon  the  nofe, 
when  its  mucous  membrane  is  inflamed,  as  in  common  catarrh. 

IV.  i.  Diuretics.  If  the  fkin  be  kept  warm,  moft  of  thefe 
medicines  promote  fweat  inftead  of  urine  ;  and  if  their  dofe  is 
enlarged,  moft  of  them  become  cathartic.  Hence  the  neutral 
falts  are  ufed  in  general  for  all  thefe  purpofes  Thofe  indeed, 
which  are  compofed  of  the  vegetable  acid,  are  moft  generally 
ufed  asfudorifics  ;  thofe  with  the  nitrous  acid  as  diuretics  ;  anti 
thofe  with  the  vitriolic  acid  as  cathartics  ;  while  thofe  united 
with  the  marine  acid  enter  our  common  nutriment,  as  a  more 
general  ftimulus.  All  thefe  increafe  the  acrimony  of  the  urine, 
hence  it  is  retained  a  lefs  time  in  the  bladder  ;  and  in  confe- 
quence  lefs  of  it  is  reabforbed  into  the  fyftem,  and  the  apparent 
quantity  is  greater,  as  more  is  evacuated  from  the  bladder  ;  but 
it  is  not  certain  from  thence,  that  a  greater  quantity  is  fecreted 
by  the  kidneys.  Hence  nitre,  and  other  neutral  falts,  are  erro- 
neoufiy  given  in  the  gonorrhoea ;  as  they  augment  the  pain  of 
making  water  by  their  ftimulus  on  the  execrated  or  inflamed 
ittethra.  They  are  alfo  erroneoufly  given  in  catarrhs  or  coughs, 

where 


38  SECERNENTIA.          ART. III.  a.  4.  2. 

where  the  difcharge  is   too  thin  and  faline,  as  they  increafe  the 
frequency  of  coughing. 

2.  Balfam  of  Copaiva  is  thought  to  promote  urine  more  than 
the  other  native  balfams  ;  and  common  refin  is  faid  to  act  as  a 
powerful  diuretic  in  horfes.     Thefe   are  alfo  much  recommend- 
ed in  gleets,  and  in  fluor  albus,  perhaps  more  than  they  deferve  ; 
they  give  a  violet  fmell  to  the  urine,  and  hence  probably  increafe 
the  fecretion  of  it. 

Calcined  egg- (hells  are  faid  to  promote  urine,  perhaps  from 
the  phofphoric  acid  they  contain. 

3,  Cold  air  and  cold  water  will  increafe  the  quantity  of  urine 
by  decreafing  the  abforprion  from  the  bladder  ,  and  neutral  and 
alkalious    falts  and  cantharides   by  ftimulating  the  neck  of  the 
bladder  to  difcharge  the  urine  as  foon  as  fecreted  ;  and  alcohol, 
as  gin  and  rum,  at  the  beginning  of  intoxication,  if  the  body  be 
kept  cool,  occafion  much  urine  by  inverting  the  urinary  lymphat- 
ics, and  thence  pouring  a  fluid  into  the  bladder,  which  never  pa'ff- 
ed  the  kidneys.     But  it  is  probable,  that  thofe  medicines,  which 
give  a  fcent  to  the  urine,  as  the  balfams  and  refins,  but  particu- 
larlyafparagus  and  garlic,  are  theonly  drugs,  which  truly  increafe 
the  fecretion  of  the   kidneys.      Alcohol  however,  ufed  as  above 
mentioned,  and  perhaps  great   dofes  of  tincture  of  cantharides, 
may  be  confidered  as  draftic  diuretics,  as  they  pour  a  fluid  into 
the  bladder  by  the  retrograde  action  of  the  lymphatics,  which 
are  in  great  abundance  ipread  about  the  neck  of  it.     See  Sect. 
XXIX.  j. 

V.  Mild  cathartics.  The  ancients  believed  that  fome  purg- 
es evacuated  the  bile,  and  hence  were  termed  Cholagogues  ; 
others  the  lymph,  and  were  termed  Hydragogues ;  and  that  in 
ihort  each  cathartic  felected  a  peculiar  humour,  which  it  dif- 
charged.  The  moderns  have  too  haftily  rejeded  this  fyftem  ; 
the  fubject  well  deferves  further  obfervation. 

Calomel  given  in  thedofe  from  ten  or  twenty  grains,  fo  as  to 
induce  purging  without  the  afliftance  of  other  drugs,  appears  to 
rne  to  particularly  increafe  the  fecretion  of  bile,  and  to  evacuate 
it ;  aloe  feems  to  increafe  the  fecretion  of  the  inteflinal  mucus  ; 
and  it  is  probable  that  the  pancreas  and  fpleen  may  be  peculiarly 
llimulated  into  action  by  fome  other  of  this  tribe  of  medicines;  , 
whilft  others  of  them  may  (imply  ftimulate  the  inteftinal  canal 
to  evacuate  its  contents,  as  the  bile  of  animals.  It  mud  be  re- 
marked, that  all  thefe  cathartic  medicines  are  fuppofed  to  be  ex- 
hibited in  their  ufual  dofes,  other  wife  they  become  draftic  purg- 
es, and  are  treated  of  in  the  Clafs  of  Invertentia. 

VI  The  mucus  of  the  bladder  is  feen  in  the  urine,  when 
cantharides  have  been  ufed,  either  internally  or  externally,  in 

fuch 


.ART.  III.  2.  7.  i.  SECERNENTIA.  39 

fuch  dofes  as  to  induce  the  ftrangury.  Spirit  of  turpentine  is 
faid  to  have  the  fame  eticct.  I  have  given  above  a  dram  of  it 
twice  a  day  floating  on  a  glafs  of  water  in  chronic  lumbago  with- 
out this  effect,  and  the  patient  gradually  recovered.  Phofpho- 
rus  may  pollibly  affect  the  mucous  glands  of  the  urethra  like 
cantharides.  See  Impotemia,  Clafs  2.  2.  3. 

VII.  Aloe  given  internally  feems  to  act  chiefly  on  the  rectum 
and  fpinctcr  ani,  producing  tenefmus  and  piles.     Externally  in 
clyfters  or  fuppodtories,  common  fait  feems  to  act  on  that  bow- 
el with  greater  certainty.      But  where  the  thread  worms  or  afcar- 
ides  exiit,   60  or  100  grains  of   aloes   reduced    to  powder  and 
boiled  in  a  pint  of  gruel,  and  ufed  as  a  clyiier  twice  a  week  for 
three  months,  has  frequently  destroyed  them.       Might  not  the 
hairs  of  filiqua  hirfuta  be  ufed  in  an  injection  for  this  purpofe  ? 
See:  Clafs  I.  i.  4.  14.     , 

VIII.  The  external  application  of  cantharides  by  (Emulating 
the  excretory  duds  of  the  capillary  glands  produces  a  great  fe- 
cretion  of  fubcutaneous  mucus    with   pain   and  inflammation  ; 
which  mucaginous  fluid,  not  being  able  to  permeate  the  cuticle, 
raifes  it  up  ;  a  fimilar  fecretion  and  elevation  of  the  cuticle  is 
produced  by  actual  fire  ;  and  by  cauftic  materials,  as  by  the  ap- 
plication of  the  juice  of  the  root  of  white  briony,  or  bruifed  muf- 
tard-feed.     Experiments  are   wanting  to  introduce  fome  acrid 
application  into  practice  inftead  of  cantharides,  which  might  not 
induce  the  ftrangury. 

MuUard-feed  alone  is  too  acrid,  and  if  it  be  fuffered  to  lie  on 
the  fkin  many  minutes  is  liable  to  produce  a  Hough  and  confe- 
quent  ulcer,  and  mould  therefore  be  mixed  with  flour  when  ap- 
plied to  cold  extremities.  Volatile  alkali  properly  diluted  might 
Stimulate  the  fkin  without  inducing  ftrangury. 

IX.  The  mild  errhincs  are  fuch  as  moderately  ftimulate  the 
membrane  of  the  noftrils,   fo   as   to  increafe  the   fecretion    of 
nafal  mucus  ;    as  is  feen   in  thofe,   who   are  habituated  to  take, 
fnufF.     The  ftronger  errhines  are  mentioned  in  Art.  V.  2.  3. 

X.  The  fecretion  of  tears  is  increafed  either  by  applying  acrid 
fubltances  to  the  eye  ;  or  acrid  vapours,  which    Stimulate  the 
excretory  duct  of  the  lachrymal  gland;  or  by  applying  them  to 
the  noftrils,  and  Simulating  the  excretory  duct  of  the  lachrymal 
fack,  as  treated  of  in  the  Section  on  Inftinct. 

Or  the  fecretion  of  tears  is  increafed  by  the  aflbctatidn  of  the 
motions  of  the  excretory  duel  of  the  lachrymal  fack  with  ideas 
of  tender  pleafure,  or  of  hooclcfs  diilrefs,  as  explained  in  Sect. 
XVI.  8  2.  and  3. 

XI.  The  fecretion  of  fenforinl  power  in  the  brain  is  proba- 
bly increafed  by  opium  or  wine,  becaufe  when  taken  in  certain 

VOL.  I.  R  R  r  quantity 


4a  SECERNENTIA.  ART.  III.  3.  i.  /. 

quantity  an  immediate  increafe  of  ftrength  and  a£Hvity  fucceeds 
for  a  time,  with  confequent  debility  if  the  quantity  taken  be  fo 
great  as  to  intoxicate  in  the  lead  degree.  The  neceffity  of  per- 
petual refpiration  (hews,  that  the  oxygen  of  the  atmofphere  fttp- 
plies  the  fource  of  the  fpirit  of  animation  -y  which  is  conftantly 
expended,  and  is  probably  too  fine  to  be  long  contained  in  the 
nerves  after  its  production  in  the  brain.  Whence  it  is  proba- 
ble, that  the  refpiration  of  oxygen  gas  mixed  with  common  air 
may  increafe  the  fecretion  of  fenforial  power  ;  as  indee^  would 
appear  from  its  exhilarating  effect  on  mod  patients. 

III.  CATALOGUE  OF  THE  SECERNENTIA. 

I.  Diaphoretics. 

1.  Amomum  zinziber,   ginger.      Carpophyllus  aromati- 

cus,  cloves.  Piper  indicum,  pepper.  Capficunu 
Cardamomum.  Pimento,  myrtus  pimenta.  Canella 
alba.  Serpentaria  virginiana,  ariftolochia  ferpenta- 
ria,  guaiacum.  Safiafras,  laurus  faflafras.  Opium. 
Wine. 

2.  Eflential  oils  of  cinnamon,  laurus  cinnamomum.  Nut- 

meg, myriftica  mofchata.  Cloves,  caryophyllus  aro- 
maticus.  Mint,  mentha.  Camphor,  laurus  campho- 
ra.  Ether. 

^.  Volatile  falts,  as  of  ammoniac  and  of  hartftiorn.     Sal 
cornu  cervi. 

4.  Neutral  falts,   as  thofe  with  vegetable  acid  ;    or  with 

marine  acid,  as  common  fait.  Halex,  red-herring, 
anchovy. 

5.  Preparations  of  antimony,  as  emetic  tartar,  antimoni- 

um  tartarizatum,  wine  of  antimony.  James's  pow- 
der. 

6.  External  applications.     Blifters.     Warm  bath.     Warm 

air.     Exercife      Fri£Hon. 

7.  Cold  water  with  fubfequent  warmth. 

II.  Sialagogues.    Preparations  of  mercury,  hydrargyrus.    Py- 

rethrum,  anthemis  pyrethrum,  tobacco,  cloves,  pepper, 
cowhage,  ftizolobium  filiqua  hirfuta.  Maftich,  pifta- 
cia  lentifcus. 

III.  Expedorants. 

i.  Squill,  fcilla  maritima,  garlic,  leek,  onion,  allium, afa- 
fcetida,  ferula  afafoetida,  gum  ammoniac,  benzoin, 
tar,  pix  liquida,  bal-am  of  Tolu. 

2.  Root  of  feneka,  poly  gala  feneka,  of  elecampane,  inula 
helenium. 

3,  Marfh-maHow 


ART.  III.  3. 3.  3.  SECERNENTIA.  41 

3.  Mar fh -mallow,  althaea, coltsfoot,  tuflilago  farafara,  gum 

arable,  mimofa  nilotica,  gum  tragacanth,  aftragalus 
tragacantha.  Deco£tion  of  barley,  hordeum  diftichon. 
Exprefied  oils.  Spermaceti,  foap.  Extract  of  liquor- 
ice, glycyrrhiza  glabra.  Sugar.  Honey. 

4.  Externally  blifters.     Oil.     Warm  bath. 

IV.  Mild  diuretics. 

1.  Nitre,  kali  acetatum,  other  neutral  falts. 

2.  Fixed  alkali,  foap,  calcined  egg-fhells. 

3.  Turpentine.     Balfam  of  Copaiva.  Refm.    Olibanum, 

4.  Afparagus,  garlic,  wild  daucus.  Pavfley,  apium.  Fen- 

nel, fceniculum,  pareira  brava,  cifTampelos  ? 

5.  Externally  cold  air,  cold  water. 

6.  Alcohol.     Tinfture  of  cantharides.     Opium. 

V.  Mild  cathartics. 

1.  Sweet  fubacid  fruits.  Prunes,  prunusdomePdca.     Caf- 

fia  fiftula.     Tamarinds,  cryftals  of  tartar,  unrefined 
fugar.     Manna.     Honey. 

2.  Whey  of  milk,  bile  of  animals. 

3.  Neutral  falts,  as  Glauber's  fait,  vitriolated  tartar,  fea- 

water,  magnefia  alba,  foap. 

4.  Gum  guaiacum.       Balfam  of  Peru.       Oleum   ricini, 

caftor-oil,  oil  of  almonds,  oil  of  olives,  fulphur 

5.  Senna,  eaffia  fenna,  jalap,   aloe,  rhubarb,   rheum  pal- 

matum, 

6.  Calomel.     Emetic  tartar,  antimonium  tartarizatum. 

VI.  Secretion  of  mucus  of  the  bladder  is  increafed  by  can 

tharides,  by  fpirit  of  turpentine  ?  Phofporus  ? 

VII.  Secretion  of  mucus  of  the  reftum  is  increafed  by  aloe 

internally, by  various  clyfters  andfuppofitoriesexternally. 

VIII.  Secretion  of  fubcutaneous  mucus  is  increafed  by  blif- 
ters of  cantharides,  by  application  of  a  thin  flice  of 
the  frem  root  of  white  briony,  by  finapifms,  by  root  of 
horfe-radim,  cochlearia  armoracia.  Volatile  alkali. 

IX.    Mild  errhines.  Marjoram.  Origanum.  Marum,  tobacco „ 

X.  Secretion  of  tears  is  increafed  by  vapour  of  iliced  onion, 

of  volatile  alkali.     By  pity,  or  ideas  of  hopelefs  diftrefb. 

XI.  Secretion  of  fenforial  power  in  the  brain  is  probably  in- 
creafed by  opium,  by  wine,  and  perhaps  by  oxygen  ga:- 
added  to  the  common  air  in  refpiration. 


ART. 


4i  SORBENTIA.  ART.  IV.  i.  r > 

ART.  IV. 
SORBENTIA. 

1.  THOSE  THINGS    which  increafe    the  irritative  motions, 
which  conftitute  abforption,  are  termed  forbemia;   and    are  as 
various  as  the  abforbent  veflels  which  they  (timulate  into  action. 

J.  Cutaneous  abforption  is  increafed  by  auftere  acids,  as  of 
vitriol ;  hence  they  are  believed  to  check  colllquative  fweats, 
and  to  check  the  eruption  of  fmall-pox,  and  contribute  to  the 
cure  of  the  itch,  and  tinea  ;  hence  they  thicken  the  faliva  in 
the  mouth,  as  lemon-juice,  crab -juice,  floes. 

2.  Abforption  from  the  mucous  membrane  is  increafed  by  opi- 
um,and  Peruvian  bark,  internally  ;  and  by  blue  vitriol  externally. 
Hence  the  expectoration  in  coughs,  and  the   mucous  difcharge 
from  the  urethra,  are  thickened  and  leflened. 

3.  Absorption  from  the  cellular  membrane  is  promoted   by 
bitter  vegetables,  and  by  emetics  and   cathartics.     Hence   mat- 
ter is  thickened  and  leffened  in  ulcers  by  opium  and  Peruvian 
bark  ,  and   ferum    is    abforbed  in  anafarca  by  the  operation  of 
emetic-  and  cathartics. 

4.  Venous  abforption  is  increafed  by   acrid    vegetables  ;  as 
water-creis,  cellery,   horfe-radifh,  muftard.     Hence  their  ufe  in 
fea  i  curvy,  the  vibices  of  which  are  owing  to  £  defeft  of  ven- 
ous abforption  ;  and  by  external  ilimulants,  as  vinegar,   and  by 
electricity,  and  perhaps  by  oxygen. 

5.  Inteftinal  abforption  is  increafed  by  atlringent  vegetables, 
as  rhubarb,  galls  ;  and  by  earthy  falts,  as  alum  ;  and  by  argilla- 
ceous and  calcareous  earth. 

6.  Hepatic  abforption  is  increafed  by    metallic  falts,  hence 
calomel  and  *al  martis  are    fo  efficacious  in  jaundice,  worms, 
chlorofis,  dropfy. 

7  Venereal  virus  in  ulcers  is  abforbed  by  the  flimulus  of 
mercury  ;  hence  they  heal  by  the  ufe  of  this  medicine. 

8.  Venefecl:ion,  hunger,  thirit,  and  violent  evacuations,  in- 
creafe all  abfurptions  j  hence  fweating  produces  coftivenefs. 

9  Externally  bitter  aftringent  vegetables,  earthy  and  metal- 
lic falts,  and  bandages,  promote  the  abforption  of  the  parts  on 
which  they  are  applied. 

10,  All  thefe  in  their  ufual  dofes  do  not  increafe  the  natural 
heat  ;  but  they  induce  coftivenefs,  and  deep-coloured  urine 
with  earthy  fediment. 

In  greater  dofes  they  invert  the  motions  of  the  ftomach  and 
lafteals  >  and  hence  vomit  or  purge,  as  carduus  benediftus, 

rhubarb. 


ART.  IV.  2.  i.  i.  SORBENTIA.  43 

rhubarb.  They  promote  perfpiration,  if  the  fkiu  be  kept  warm; 
as  camomile  tea,  and  teftaceous  powders,  have  been  ufed  as 
fudorifics. 

The  preparations  of  antimony  vomit,  pir-ge,  or  fweat,  either 
according  to  the  quantity  exhibited,  or  as  a  part  of  what  is  giv- 
en is  evacuated.  Thus  a  quarter  of  a  grain  of  emetic  tartar  (if 
well  prepared)  will  produce  a  diaphorefis,  if  the  fkin  be  kept 
warm  ;  half  a  grain  will  promote  a  ftool  or  two  firft,  and  fweat- 
ing  afterward  ;  and  a  grain  will  generally  vomit,  and  then 
purge,  and  laftly  fweat  the  patient.  In  lefs  quantity  it  is  prob- 
able, that  this  medictne  afts  like  other  metallic  fairs,  as  fteel, 
zinc,  or  copper  in  {mall  dofes  ;  that  is,  that  it  Strengthens  the 
fyfiem  by  its  ftimulus.  As  camomile  and  rhubarb  in  different 
dofes  vomit,  or  purge,  or  acl  as  (limulants  fo  as  to  (trengthen 
the  fyltem. 

Some  of  the  medicines  of  this  clafs  of  forbentia  have  been 
termed  tonics  by  fome  authors,  as  giving  due  tone  to  the  ani- 
mal fibre.  But  it  fhould  be  obferved,  that  tone  is  a  mechanical 
term,  applicable  only  to  mufical  firings,  and  like  bracing  and  re- 
laxation, cannot  be  applied  to  animal  life  except  metaphorically. 
The  /ame  may  be  obferved  of  the  word  reaction,  ufed  by  fome 
modern  authors,  which  in  its  proper  figniiication  is  a  mechani- 
icai  term  inapplicable  to  the  laws  of  life  except  metaphorically., 

II.  OBSERVATIONS  ON  THE  SORBENTIA. 

I.  T.  As  there  is  great  difference  in  the  apparent  flruc~lure 
of  the  various  glands,  and  of  the  fluids  which  they  felecl  from 
the  blood,  thefe  glands  mtift  pofTefs  different  kinds  of  irritabili- 
ty, and  are  therefore  ihmulated  into  ftronger  or  unnatural  ac- 
tions by  different  articles  of  the  materia  inedica,  as  {hewn  in  the 
fecernertia.  Now  as  the  abforbent  vefTels  are  likewife  glands, 
and  drink  up  or  felecl  different  fluids,  as  chyle,  water,  mucus, 
with  a  part  of  every  different  fecretion,  as  a  part  of  the  bile,  a 
part  of  the  faliva,  a  part  of  the  urine,  &c.  it  appears,  that  thefe 
abforbent  veffels  muft  likewife  poflefs  different  kinds  of  irrita- 
bility, and  in  confequence  muft  require  different  articles  of  the 
materia  medica  to  excite  them  into  unufual  action.  This  part 
of  the  fubjeft:  has  been  fo  little  attended  to,  that  the  candid 
reader  will  find  in  this  article  a  great  deal  to  excufe. 

It  was  obferved  that  fome  of  the  fecernemia  did  in  a  lefs  de- 
gree increafe  abforption,  from  the  combination  of  different  prop- 
erties in  the  fame  vegetable  body  ;  for  the  fame  reafon  fome  of 
the  clafs  of  forbentia  produce  fecretion  in  a  lefs  degree,  as  thofe 
bitters  which  have  alfo  an  aroma  in  their  compofition  ;  thefe 

are 


44  SORBENTIA.  ART.  IV.  2.1.2. 

are  known  from  their  increafing  the  heat  of  the  fyftem  above 
its  ufual  degree. 

It  muft  alfo  be  noted,  that  the  adtions  of  every  part  of  the 
abforbent  fyftem  are  fo  affociated  with  each  other,  that  the 
drugs  which  ftimulate  one  branch  increafe  the  action  of  the 
whole  ;  and  the  torpor  or  quiefcence  of  one  branch  weakens  the 
exertions  of  the  whole  ;  or  when  one  branch  is  excited  into 
ftronger  action,  fome  other  branch  has  its  actions  weakened  or 
inverted.  Yet  though  peculiar  branches  of  the  abforbent  fyf- 
tem are  ftimulated  into  action  by  peculiar  fubftances,  there  are 
other  fubftances  which  feem  to  ftimulate  the  whole  fyftem,  and 
that  without  immediately  increafing  any  of  the  fecretions  ;  as 
thofe  bitters  which  poffefs  no  aromatic  fcent,  at  the  head  of 
which  (lands  the  famed  Peruvian  bark,  or  cinchona. 

2.  Cutaneous  abforption.  I  have  heard  of  fome  experi- 
ments, in  which  the  body  was  kept  cold,  and  was  thought  to 
abforb  more  moifture  from  the  atmofphere  than  at  any  other 
time.  This  however  cannot  be  determined  by  ftatical  experi- 
ments :  as  the  capillary  veffels,  which  fecrete  the  perfpirable 
matter,  muft  at  the  fame  time  have  been  benumbed  by  the  cold  j. 
and  from  their  inaction  there  could  not  have  been  the  ufual 
wafte  of  the  weight  of  the  body  ;  and  as  all  other  mufcular  ex- 
ertions are  beft  performed,  when  the  body  poffeffes  its  ufual  de- 
gree of  warmth,  it  is  conclufive,  that  the  abforbent  fyftem  fhould 
likewife  do  its  office  beft,  when  it  is  not  benumbed  by  external 
cold. 

The  auftere  acids,  as  of  vitriol,  lemon-juice,  juice  of  crabs  and 
floes,  ftrengthen  digeftion,  and  prevent  that  propenfity  to  fweat 
fo  ufual  to  weak  convalefcents,  and  diminifh  the  colliquative 
fvveats  in  hectic  fevers  ;  all  which  are  owing  to  their  increafing 
the  action  of  the  external  and  internal  cutaneous  abforption. 
Hence  vitriolic  acid  is  given  in  the  fmall-pox  to  prevent  the  too 
hafty  or  too  copious  eruption,  which  it  effects,  by  increafing  the 
cutaneous  abforption.  Vinegar,  from  the  quantity  of  alcohol 
which  it  contains,  exerts  a  contrary  effect,  to  that  here  defcrib- 
ed,  and  belongs  to  the  incitantia  ;  as  an  ounce  of  it  promotes 
fweat,  and  a  flufhing  of  the  fkin  ;  at  the  fame  time  externally  it 
acts  as  a  venous  abforbent,  as  the  lips  become  pale  by  moiften- 
ing  them  with  it.  And  it  is  faid,  when  taken  internally  in  great 
and  continued  quantity,  to  induce  palenefs  of  the  fkin,  and  foft- 
nefs  of  the  bones. 

The  fweet  vegetable  acids,  as  of  feveral  ripe  fruits,  are  among 
the  torpentia ;  as  they  are  lefs  ftimulating  than  the  general  food 
of  this  climate,  and  are  hence  ufed  in  inflammatory  difeafes. 

Where  the  quantity  of  fluids  in  the  fyftem  is  much  leffened. 


ART.  IV.  2.  i.  3 -  SORBENTIA.  45 

as  in  hectic  fever,  which  has  been  of  fome  continuance,  or  in 
fpurious  peripneumony,  a  grain  of  opium  given  at  night  will 
fometimes  prevent  the  appearance  of  fweats  ;  which  is  owing  to 
the  ftimulus  of  opium  increafing  the  actions  of  the  cutaneous 
abforbents,  more  than  thofe  of  the  fecerning  veflels  of  the  (kin. 
Whence  the  iecretion  of  perfpirable  matter  is  not  decreafecl, 
but  its  appearance  on  the  {kin  is  prevented  by  its  more  facile 
abforption. 

3.  There  is  one  kind  of  itch,  which  feldom  appears  between 
the  fingers,  is  the  leaft  infectious,  and  molt  difficult  to  eradicate, 
and  which  has  its  cure    much   facilitated  by  the  internal  ufe  of 
acid  of  vitriol.     This  difeafe  confifts  of  fmall  ulcers  in  the  ikin, 
which  are  healed  by  whatever  increafes  the  cutaneous  abforp- 
tion.    The  external  application  of  fulphur,  mercury,  and  acrid 
vegetables,    acts  on  the  fame  principle ;    for  the  animalcula, 
which  are  feen  in  thefe  puftules,  are  the  effect,  not  the  caufe,  of 
them  ;  as  all  other  ftagnating  animal  fluids,  as  the  femen  itfelf, 
abounds    with  fimilar    microfcopic  animals.      See  Dyfentery, 
ClafsII.  i.  3.    18. 

4.  Young  children  have  fometimes  an  eruption  upon  the  head 
called  tinea,  which  difcharges  an  acrimonius   ichor  inflaming 
the  parts,  on  which  it  falls.     This  eruption  I  have  feen  fubmit 
to  the  internal  ufe  of  vitriolic  acid,  when  only  wheat-flour  was 
applied  externally.     This  kind  of  eruption  is  likewife  frequent- 
ly cured  by  teftaceous  powders  ;  two  materials  fo  widely  differ- 
ent in  their  chemical  properties,  but  agreeing  in  their  power  of 
promoting  cutaneous  abforption. 

II.  Abforption  from  the  mucous  membrane  is  increafed  by 
applying  to  its  furface  the  auftere  acids,  as  of  vitriol,  lemon-juice, 
crab-juice,  floes.  When  thefe  are  taken  into  the  mouth,  they 
immediately  thicken,  and  at  the  fame  time  leflen  the  quantity  of 
the  faliva  ;  which  laft  circumftance  cannot  be  owing  to  their 
coagulating  the  faliva,  but  to  their  increafing  the  abforption  of 
the  thinner  parts  of  it.  So  alum  applied  to  the  tip  of  the  tongue 
does  not  flop  in  its  action  there,  but  independent  of  its  diffufion 
it  induces  cohefion  and  corrugation  over  the  whole  mouth.  (Cul- 
len's  Mat.  Med.  Art.  Aftringentia.)  Which  is  owing  to  the 
affociation  of  the  motions  of  the  parts  or  branches  of  the  abforb- 
ent  fyftem  with  each  other. 

Abforption  from  the  mucous  membrane  is  increafed  by  opium 
taken  internally  in  fmall  dofes  more  than  by  any  other  medicine, 
as  is  feen  in  its  thickening  the  expectoration  in  coughs,  and  the 
difcharge  from  the  noftrils  in  catarrh,  and  perhaps  the  difcharge 
from  the  urethra  in  gonorrhoea.  The  bark  feems  next  in  pow- 
er for  all  thefe  purpofes. 

External!? 


46  SORBENTIA.  ART  IV.  2. 3.  i. 

Externally  flight  folutions  of  blue  vitriol,  as  two  or  three 
grains  to  an  ounce  of  water,  applied  to  ulcers  of  the  mouth,  or 
to  chancres  on  the  glans  penis,  more  powerfully  induce  them  to 
heal  than  any  other  material. 

Where  the  lungs  or  urethra  are  inflamed  to  a  confiderable 
degree,  and  the  abforption  is  fo  great,  that  the  mucus  is  already 
too  thick,  and  adheres  to  the  membrane  from  its  viscidity,  opi- 
ates and  bitter  vegetable  and  auitere  acids  are  improper  ;  and 
mucilaginous  diluent  (hould  be  ufed  in  their  (lead  with  venefec- 
don  and  torpentia. 

III.  i.  Abforption  from  the  cellular  membrane,  and  from  all 
the  other  cavities  of  the  body,  is  too  flowly  performed  in  fome 
conftitutions ;  hence  the  bloated  pale  complexion  ;  and  when 
this  occurs  in  its  greateft  degree,  it  becomes  an  univerfal  dropfy. 
Thefe  habits  are  liable  to  intermittent  fevers,  hylleric  paroxyfms, 
cold  extremities,  indigdtion,  and  all  the  fymptoms  of  debility. 

The  abforbent  fyftem  is  more  fubjecl;  to  torpor  or  quiefcence 
than  the  fecerning  fyftem,  both  from  the  coldneis  of  the  fluids 
which  are  applied  to  it,  as  the  moifture  of  the  atmofphere,  and 
from  the  coldnefs  of  the  fluids  which  we  drink  ;  and  allo  from 
its  being  (limulated  only  by  inter /als,  as  when  we  take  our  food  ; 
whereas  the  fecerning  fyftem  is  perpetually  excited  into  a  hon 
by  the  warm  circulating  blood  ;  as  explained  in  S^cl  XXXII. 

2.  The  Peruvian  bark,  camomile  flowers,  and  other  bitter 
drugs,  by  ftimulating  this  cellular  branch  of  rhe  abforbent  fyitem 
prevents  it  from  becoming  quiefcent  j  hence  'he  cold  paroxyfms 
of  thofe  agues,  which  arife  from  the  torpor  of  the  cellular  lymph- 
atics, are  prevented,  and  the  hot  firs  in  confequence  The 
patient  thence  preferves  his  natural  heat,  regains  his  healthy 
colour,  and  his  accuftomed  ftrength. 

Where  the  cold  paroxyfm  of  an  ague  originates  in  the  abforl>- 
ents  of  the  liver,  fpleen,  or  other  internal  vifcus,  the  addition  of 
fteel  to  vegetable  bitters,  and  eipecially  after  the  ufe  of  one 
dofe  of  calomel,  much  advances  the  cure. 

And  where  it  originates  in  any  part  of  the  fecerning  fyftem, 
as  is  probably  the  cafe  in  fome  kind  of  agues,  the  addition  of 
opium  in  the  dofe  of  a  grain  and  half,  given  about  an  hour  be- 
fore the  accefs  of  the  paroxyfm,  or  mixed  with  the  chalybeate  and 
bitter  medicines,  enfures  the  cure,  Or  the  fame  may  be  efFec-led 
by  wine  given  inftead  of  opium  before  the  paroxyfm,  fo  as  near- 
ly to  intoxicate. 

Thefe  three  kinds  of  agues  are  thus  diftinguiflied  ;  the  firftis 
not  attended  with  any  tumid  or  indurated  vifcus,  which  the  peo- 
ple call  an  ague  cake,  and  which  is  evident  to  the  touch.  The 
iecond  is  accompanied  with  a  tumid  vifcus  j  and  rhe  laft  has 

generally, 


ART.  IV.  2.3.  3.  SORBENTIA.  47 

generally,  I  believe,  the  quartan  type,  and  is  attended  with  fome 
degree  of  arterial  debility. 

The  bark  of  the  broad-leaved  willow  or  folix  caprea  of  Linne- 
us,  is  much  recommended  as  equal  to  the  Peruvian  bark  given 
in  the  fame  or  in  greater  quantity  by  Mr.  White  of  Bath.  Ob- 
ferv.  and  Exper.  on  broad-leafed  willow.  Vernor  and  Hood, 
London.  A  Dr.  Gunz  in  Germany  recommends  a  lib  as  a  fub- 
ftitute  for  Peruvian  bark,  the  bark  of  fix  fpecies  of  willow,  the 
falix  alba,  pentandra,  fragilis,  caprea,  vitellina,  and  amygdalina, 
Dr.  Gunz  believes  fome  of  thefe  barks  to  be  more  efficacious 
than  the  Peruvian.  And  as  fome  of  thefe  willow-barks  may  bo- 
procured  in  great  quantity,  as  they  are  (tripped  off  from  the  wil- 
low twigs  ufed  by  the  bafket-makers  in  many  parts  of  the  coun- 
try in  the  vernal  months,  it  would  feem  to  be  an  article  worth 
attending  to. 

The  root  of  geum  urbanum,  avens,  is  recommended  as  a  (ub~ 
ftitute  for  Peruvian  bark  by  Dr.  Vogel,  and  faid  to  cure  the 
quartan  ague  given  in  the  dote  of  half  a  dram  every  hour  through 
the  day.  The  datifca  cannabina  of  Linneus  is  alfo  faid  to  equal 
the  Peruvian  bark  in  its  febrifuge  virtues.  Medical  and  Phyfical 
Journal,  Vol.  I.  p.  191. 

3.  This  clafs  of  abforb^nt  medicines  are  faid  to  decreafe  irri- 
tability.    After    any  part  of  our  fyilem  has  been  torpid  or  qui- 
efcent,  by  whatever  caufe  that  was  produced,  it  becomes  after- 
wards capable  of   being   excited  into  greater  motion  by  fmall 
ftimuli  ;  hence  the  hot  fit  of  fever  fucceeds  the  cold  one.      As 
thefe  medicines  prevent  torpor  or  quiefcence  of  parts  of  the  fvf- 
tem,  as  cold  hands  or   feet,  which  perpetually  happen  to  weak 
conftitutions,  the  fubfequent  increafe  of  irritability  of  thefe  parts 
is  likewife  prevented. 

4.  Thefe  abforbent  medicines,  including  both  the  bitters, 
and  metallic  falts,  and  opiates,  are  of  great  ufe  in  the  dropfy  by 
their  promoting  univerfal   abforption  ;  but  here  evacuations  are 
likewife  to  be  produced,  as  will  be  treated  of  in  the  Invertentia, 

5.  The  matter  in    ulcers  is   thickened,  and  thence  rendered 
lefs  corrofive,  the  faline  part  of  it  being  reabforbed  by  the  ufe 
of  bitter  medicines  ;  hence   the  bark  is  ufed  with  advantage  in 
the  cure  of  ulcers. 

6.  Bitter  medicines  flrengthen  digeftion  by  promoting  the 
abforption  of  chyle  j  hence  the  introduftion  of  hop  into  the  po- 
tation ufed  at  our  meals,  which  as  a  medicine  may  be  taken  ad  - 
vantageoufly,  but,  like  other  unnecefTary  ftimuli,  muft  be  injuri- 
ous as  an  article  of  our  daily  diet. 

The  hop  may  perhaps  in  fome  degree  contribute  to  the  pro- 
duclion  oif  gravel  in  the  kidneys,  as  our  intemperate  wine-drink* 
VOL.  I.  S   s  f  err, 


48  SORBENTIA.  ART.  IV.  2.  3.  7. 

ers  are  more  fubject  to  the  gout,  and  ale-drinkers  to  the  gravel  ; 
in  the  formation  of  both  which  difeafes,  there  can  be  no  doubt, 
but  that  the  alcohol  is  the  principal,  if  not  the  only  agent. 

7,  Vomits  greatly  increafe  the  abforption  from  the  cellular 
membrane,  as  fquill,  and  foxglove.  The  fquill  (hould  be  given 
in  the  dofe  of  a  grain  of  the  dried  root  every  hour,  till  it  ope- 
rates upwards  and  downwards.  Four  ounces  of  the  frefh  leaves 
of  the  foxglove  mould  be  boiled  from  two  pounds  of  water  to 
one,  and  half  an  ounce  of  the  decoction  taken  every  two  hours 
for  four  or  more  dofes.  This  medicine,  by  ftimulating  into  in- 
verted action  the  abforbents  of  the  ftomach,  increafes  the  direct 
action  of  the  cellular  lymphatics. 

Another  more  convenient  way  of  afcertaining  the  dofe  of 
foxglove  is  by  making  a  faturated  tincture  of  it  in  proof  fpirit  ; 
which  has  the  twofold  advantage  of  being  invariable  in  its  orig- 
inal ftrength,  and  of  keeping  a  long  time  as  a  (hop-medicine 
without  lofing  any  of  its  virtue.  Put  two  ounces  of  the  leaves 
of  purple  foxglove,  digitalis  purpurea,  nicely  dried,  and  coarfely 
powdered,  into  a  mixture  of  four  ounces  of  rectified  fpirit  of 
wine  and  four  ounces  of  water  ;  let  the  mixture  (land  by  the 
fire-fide  twenty-fours  hours  frequently  making  the  bottle,  and 
thus  making  a  faturated  tincture  of  digitalis  ;  which  muit  be 
poured  from  the  fediment  or  pafled  through  filtering  paper. 

Some  perfon  has  lately  objected  to  the  quantity  of  the  dried 
leaves  of  digitalis  ufed  in  this  tincture  as  an  unneceiTary  ex- 
penfe  ;  not  knowing  that  the  plant  grows  fpontaneoufly  by  cart- 
loads in  all  fandy  fituations,  and  not  recollecting  that  the  cer- 
tainty of  procuring  this  medicine  at  all  times  of  the  year,  and 
from  all  (hops  of  the  fame  degree  of  ftrength,  is  a  circumftance 
of  great  importance. 

As  the  fize  of  a  drop  is  greater  or  lefs  according  to  the  fize  of 
the  rim  of  the  phial  from  which  it  is  dropped,  a  part  of  this 
faturated  tincture  is  then  directed  to  be  put  into  a  two-ounce 
phial,  for  the  purpofe  of  afcer raining  the  fize  of  the  drop. 
Thirty  drops  of  this  tincture  are  directed  to  be  put  into  an 
ounce  of  mint-water  for  a  draught  to  be  taken  twice  or  thrice 
a  day,  till  it  reduces  the  anafarca  of  the  limbs,  or  removes  the 
difficulty  of  breathing  in  hydrothorax,  or  till  it  induces  frcknefs. 
And  if  thefe  do  not  occur  in  two  or  three  days,  the  dofe  muft 
be  gradually  increafed  to  forty  or  fixty  drops,  or  further. 

A  lady,  who  was  92  years  of  age,  was  feized  fuddenly,  early 
in  the  morning,  with  great  difficulty  of  refptration,  which  con- 
tinued in  greater  or  lefs  degree  in  fpite  of  many  medicines  for 
two  or  three  weeks.  Her  legs  were  than  become  cedematous, 
and  (he  could  not  lie  down  horizontally.  On  taking  thirty 

drops 


ART.  IV.  2. 3. 8.  SORBENTIA.  %9 

drops  of  the  faturated  tincture  of  digitalis  from  a  two-ounce 
phial  twice  a  day,  (he  became  free  from  the  difficult  refpira- 
tion,  and  her  legs  became  lefs  fwelled,  in  two  or  three  days. 
She  has  repeated  this  medicine  about  once  a  month  for  more 
than  a  year,  with  tincture  of  bark  at  intervals,  and  half  a  grain 
of  opium  at  night,  and  retains  a  tolerable  (late  of  health. 

From  the  great  ftimulus  of  this  medicine  the  flomach  is  ren- 
dered torpid  with  confequent  (icknefs,  which  continues  many 
hours  and  even  days,  owing  to  the  great  exhauftion  of  its  fe nib- 
rial  power  of  irritation  ;  and  the  action  of  the  heart  and  arteries 
becomes  feeble  from  the  deficient  excitement  of  the  fenforial 
power  of  aflbciation  ;  and  laflly,  the  abforbents  of  the  cellular 
membrane  act  more  violently  in  confequence  of  the  accumula- 
tion of  the  fenforial  power  of  aflbciation  in  the  torpid  heart  and 
arteries,  as  explained  in  Suppl.  I.  12. 

A  circumftance  curioufly  fimilar  to  this  occurs  to  fome  peo- 
ple on  fmoking  tobacco  for  a  fhort  time,  who  have  not  been  ac- 
cuflomed  to  it.  A  degree  of  ficknefs  is  prelently  induced,  and 
the  pulfations  of  the  heart  and  arteries  become  feeble  for  a  fhort 
time,  as  in  the  approach  to  fainting,  owing  to  the  direct  fym- 
pathy  between  thefe  and  the  flomach,  that  is  from  defect  of 
the  excitement  of  the  power  of  aflbciation.  Then  there  fuc- 
ceed  a  tingling,  and  heat,  and  fometimes  fweat,  owing  to  the  iri- 
creafed  action  of  the  capillaries,  or  perfpirative  and  mucous 
glands  ;  which  are  occafioned  by  the  accumulation  of  the  fen- 
forial power  of  aflbciation  by  the  weaker  action  of  the  heart  and 
arteries,  which  now  increafes  the  action  of  the  capillaries. 

8.  Another  method  of  increafing  abforption  from  the  cellu- 
lar membrane  is  by  warm  air,  or  by  warm  fteam.  If  the  fweli- 
ed  legs  of  a  dropfical  patient  are  enclofed  in  a  box,  the  air  of 
which  is  made  warm  by  a  lamp  or  two,  copious  fweats  are  foon 
produced  by  the  increafed  action  of  the  capillary  glands,  which 
are  feen  to  (land  on  the  fkin,  as  it  cannot  readily  exhale  in  fo 
fmall  a  quantity  of  air,  which  is  only  changed  fo  fail  as  may  be 
neceflary  to  permit  the  lamps  to  burn.  At  the  fame  time  the 
lymphatics  of  the  cellular  membrane  are  flimulated  by  the  heat 
mto  greater  action,  as  appears  by  the  fpeedy  reduction  of  the 
tumid  legs. 

It  would  be  well  worth  trying  an  experiment  upon  a  perfon 
labouring  under  a  general  anafarca  by  putting  him  into  a  room 
filled  with  air  heated  to  120  or  130  degrees,  which  would  prob- 
ably excite  a  great  general  diaphorefis,  and  a  general  cellular  ah- 
forption  both  from  the  lungs  and  every  other  part.  And  that 
air  of  fo  great  heat  may  be  borne  for  many  minutes  without 

great 


5o  SORBENTIA.  ART.  IV.  2.3.9, 

great  inconvenience  was  (hewn  by  the  experiments  made  in 
heated  rooms  by  Dr.  Fordyce  and  others.  Philof.  Tranf. 

Another  experiment  of  ufing  warmth  in  anafarca,  or  in  oth- 
er difcates,  might  be  by  immerfing  the  patient  in  warm  air,  or 
in  warm  fleam,  received  into  an  oil-fkin  bag,  or  bathing-tub  of 
tin,  fo  managed,  that  the  current  of  warm  air  or  fleam  fhould 
pals  round  and  cover  the  whole  of  the  body  except  the  head, 
which  might  not  be  expofed  to  it  ;  and  thus  the  abforbents  of 
the  lungs  might  be  induced  to  aft  more  powerfully  by  1'ympa- 
thy  with  the  fkin,  and  not  by  the  flimulus  of  heat.  See  Ufes 
of  Warm  Bath,  Art.  II.  2.  2.  i. 

A  warm  faline  pediluvium  has  often  been  ufed  with  fuccefs 
to  remove  fwellings  of  the  legs  from  deficient  action  of  the  ab- 
forbents of  the  lower  extremities  ;  the  quantity  of  fea-falt  fhould 
be  about  one  thirtieth  part  of  the  water*  which  with  about  one 
eightieth  part  of  fulphuric  magnefian  fait,  called  magnefia  vitri- 
olata,  or  bitter  cathartic  fait,  conftitutes  the  medium  flrength  of 
the  fea-water  round  this  iiland,  according  to  the  experiments  of 
Mr.  Brovvnrig.  In  fuch  a  pediluvium  the  fwelled  legs  fbould 
be  immerfed  for  half  an  hour  every  night  for  a  fortnight,  at  the 
heat  of  about  go  or  98  degrees. 

Dr.  Reid,  in  a  Treatife  on  Sea-bathing  ;  Cadell  and  Davis, 
London  ,  recommends  an  univerfal  warm-bath  of  fea-water,  in 
cedematous  fwellings,  apparently  with  great  fuccefs,  and  well 
advifes  friction  to  be  diligently  ufed  in  the  bath  on  the  tumid 
limbs,  always  rubbing  them  from  their  extremities  towards  the 
trunk  of  the  body,  and  not  the  contrary  way  ;  as  this  mufl  mofi 
facilitate  the  progrefs  of  the  fluids  in  the  abforbent  fyflem  ; 
though  thefe  veflels  are  furnifhed  with  valves  to  prevent  its  re- 
turn. In  thefe  baths  the  flimulus  of  the  fait  is  added  to  that  of 
the  heat.  See  Art.  II.  2  2.  i. 

9.  Another  method  of  increafing  abforption  from  the  cellu- 
lar membrane,  which  has  been  ufed  in  dropfies,  has  been  by  the 
great  or  total  abflinence  from  fluids.  This  may  in  fome  degree 
be  ufed  advantageoufly  in  fubjefts  of  too  great  corpulency,  but 
if  carried  to  excefs  may  induce  fevers,  and  greater  evils  than 
it  is  defigned  to  counteract,  befides  the  perpetual  exiflence 
of  a  painful  thirft.  In  moft  dropfies  the  thirfl  already  exifling 
{hews,  that  too  little  diluent  fluid,  and  not  too  much,  is  prefent 
Jn  the  circulation. 

IV.  i.  Venous  abforption.  Cellery,  watercrefTes,  cabbages, 
and  many  other  vegetables  of  the  clafs  tetradynamia,  do  not  in- 
creafe  the  heat  of  the  body  (except  thofe,  the  acrimony  of  which 
approaches  to  coirofion,  and  hence  they  feern  alone,  or  princi- 
pally, to  aft  on  the  venous  fyftem  -?  the  extremities  of  which  we 

have 


ART  IV.  2.  4.  2.  SORBENTIA.  5 1 

have  fhewn  are  abforbents  of  the  red  blood,  after  it  has  pafTecl 
the  capillaries  and  glands. 

2.  In  the  fea-fcurvy  and  petechial  fever  the  veins  do  not  per- 
fe&Jy  perform  this  office  of  abforption  ;  and  hence  the  vibices 
are  occjfioned    by   blood  ftagnating  at  their  extremities,  or  ex- 
travafated  into  the  cellular  membrane.   And  this  clafs  of  vegeta- 
bles, ftimulating  the   veins  to  perform  their  natural  abforption, 
without   increafmg   the  energy  of  the  arterial  action,  prevents 
future  petechiae,  and   may  affift  the  abforption  of  the  blood  al- 
ready ftagnated,  as  foon  as  its  chemical  change  renders  it  proper 
for  that  operation. 

3.  The  fluids,  which  are  extravafated,  and  received  into  the 
cells  of  the  cellular  membrane,  fcem  to  continue  there  for  many 
days,  fo  as  to  undergo  fome  chemical  change,  and  are  then  taken 
up  again   by    the  mouths  of  the  cellular  abforbents.     But  the 
new  veiTels  produced    in  inflamed  parts,  as  they  communicate 
with  the   veins,  are  probably  abforbed  again  by  the  veins  along 
with  the  blood  which  they  contain  in  their  cavities.    Hence  the 
blood,  which  is  extravafated  in  bruifes  of  vibices,  is  gradually 
many  days  in    difappearing  ;  but  after  due  evacuations  the  in- 
flamed vefTels  on  the  white  of  the  eye,  if  any  flimulant  lotion  is 
applied,  totally  difappear  in  a  few  hours. 

Amongft  abforbents  ;aTecling  the  veins  we  (hould  therefore 
add  the  external  application  of  flimulant  materials  ;  as  of 
vinegar,  which  makes  the  lips  pale  on  touching  them.  Fric- 
tion, and  eleclricity. 

4.  Haemorrhages  are  of  two  kinds,  either  arterial,  which  are 
attended    with  inflammation  ;  or  venous,  from  a  deficiency  in 
the  abforbent  power  of  this  fet  of  vefTels.     In  the  former  cafe 
the  torpentia  are  efficacious  ;  in  the  latter  (leel,  opium,  alum, 
and  all  the  tribe  of  forbcntia,  are  ufed  with  fuccefs. 

5.  Sydenham  recommends  vegetables  of  the  clafs  tetradyna- 
mia   in  rheumatic  pains  left  after  the  cure  of  interrnittents. 
Thefe  pains  are  perhaps   finiilar  to  thofe  of  the  fea-fcurvy,  and 
feem  to  arife   from  want  of  abforption  in  the  affected  part,  and 
hence  are  relieved  by  the  fame  medicines. 

V.  i.  Inteftinal  abforption.  Some  aflringent  vegetables,  af> 
rhubarb,  may  be  given  in  fuch  dofes  as  to  prove  cathartic  ;  and, 
after  a  part  of  it  is  evacuated  from  the  body,  the  remaining 
part  augments  the  abforption  of  the  inteftines  ;  and  a£ts,  as  if 
a  fimilar  dofe  had  been  exhibited  after  the  operation  of  any  oth- 
er purgative.  Hence  4  grains  of  rhubarb  itrengthen  the  bow- 
els,  30  grains  firil  empty  them. 

.2    The  earthy    falts,  as  alum,  increafe  the  inteflinal  abforp- 
tion, and  hence   induce  conftipation  in  their  ufual  dofe  ;  alum 

is 


52  SORBENTIA.  ART.  IV.  2. 5. 3 

is  faid  fometimes  to  cure  intermitrents,  perhaps  when  their  feat 
is  in  the  inteftines,  when  other  remedies  have  failed.  It  is  ufe- 
ful  in  the  diabetes,  by  exciting  the  abforbents  of  the  bladder  in- 
to their  natural  adion  ;  and  combined  with  refm  is  efteemed 
in  the  fluor  albus,  and  in  gleets.  Lime-ftone  or  chalk,  and 
probably  gypfum,  poflefs  effefts  in  fome  degree  fimilar,  and  in* 
creafe  the  abforption  of  the  inteftines  ;  and  thus  in  certain  do- 
fes  reftrain  fome  diarrhoeas,  but  in  greater  dofes  alum  I  fup- 
pofe  will  aft  as  a  cathartic.  Five  or  ten  grains  produce  coniti* 
pation,  20  or  30  grains  are  either  emetic  or  cathartic. 

3.  Earth  of  alum,  tobacco-pipe  clay,  marl,  Armenian  bole, 
lime,  crab's  eyes  or  claws,  and  calcined  hartihorn,  or  bone  a(h- 
es,  reftrain  fluxes  ;  either  mechanically  by  fupplying  fomething 
like  mucilage,  or  oil,  or  rollers  to  abate  the  friftion  of  the  ali- 
ment over  inflamed  membranes  j  or  by  increafing  their  abforp- 
tion. The  two  laft  confift  of  calcareous  earth  united  to  phof- 
phoric  acid,  and  the  Armenian  bole  and  marl  may  contain  iron. 
By  the  confent  between  the  inteftines  and  the  fkin  20  grains  of 
Armenian  bole  given  at  going  into  bed  to  heftic  patients  will 
frequently  check  their  tendency  to  fweat  as  well  as  to  purge, 
and  the  more  certainly  if  joined  with  one  grain  of  opium. 

VI.  i.  Abforption  from  the  liver,  flomach,  and  other  vifcera. 
When  inflammations  of  the  liver  are  fubdued  to  a  certain  de- 
gree by  venefeclion,  with  calomel  and  other  gentle  purges,  fo 
that  the  arterial  energy  becomes  weaked,  four  or  eight  grains 
of  iron  filings,  or  of  fait  of  fteel,  with  the  Peruvian  bark,  have 
wonderful  effecl:  in  curing  the  cough,  and  reftoring  the  liver  to 
its  ufual  fize  and  fanity  j  which  it  feems  to  effecl:  by  increafing 
the  abforption  of  this  vifcus.  The  fame  I  fuppofe  happens  in 
rcfpeft  to  the  tumours  of  other  vifcera,  as  of  the  fpleen,  or  pan- 
creas, fome  of  which  are  frequently  enlarged  in  agues. 

2.  Haemorrhages  from  the  nofe,  reclum,  kidneys,  uterus,  and 
other  parts,  are  frequently  attendant  on  difeafed  livers  ;  the 
blood  being  impeded  in  the  vena  portarum  from  the  decreafed 
power  of  abforption,  and  in  confequence  of  the  increafed  fize  of 
this  vifcus.  Thefe  haemorrhages  after  venefeft ion,  and  a  mer- 
curial cathartic,  are  mod  certainly  reftrained  by  fteel  alone,  or 
joined  with  an  opiate  ;  which  increafe  the  abforption  and  di» 
minifti  the  fize  of  the  liver. 

Chalybeates  may  alfo  reftrain  thefe  haemorrhages  by  their 
promoting  venous  abforption,  though  they  exert  their  principal 
effecl:  upon  the  liver.  Hence  alfo  opiates,  and  bitters,  and  vit- 
riolic acid  are  advantageoufly  ufed  along  with  them.  It  mud 
be  added  that  fome  haemorrhages  recur  by  periods  like  the  par- 

oxyfms 


ART.  IV.  2. 6. 3.  SORBENTIA.  53 

oxyfms  of  intermittent  fevers,  and  are  thence  cured  by  the  fame 
treatment, 

3.  The  jaundice  is  frequently  caufed  by  the  infipidity  of  the 
bile,  which  does  not  (liumlate  the  gall-bladder  and  bile- duels  in- 
to their  due  a&ion  -,  hence  it  ftagnates  in  the  gall-bladder,  and 
produces  a  kind  of  cryftallization,   which  is  too  large  to  pafs  in- 
to the  inteftines,  blocks  up  the  bile-duft,   and  occaiions  a   long 
n-ul  painful  difeafe.     A  paralyfis  of  the    bile-ducl   produces  a 
fnnilar  jaundice,  but  without  pain. 

4.  Worms   in  (heep  called  flukes   are  owing  to  the  dilute 
(late  of  the    bile  ;  hence  they  originate  in  the  inteftines,  and 
thence  migrate  into  the  biliary  dufts,    and  corroding  the    liver 
produce  ulcers,  cough,  and  heftic  fever,  called  the  rot.     In  hu- 
man bodies  it  is  probable  the  inert  (late  of  the  bile  is  one  caufe 
of  the  production  of  worms ;  which  infipid  ftate  of  the  bile  is 
owing  to  deficient  abforption  of  the  thinner  parts  of  it ;  hence 
the  pale  and  bloated  complexion,  and  f welled  upper  lip,  of  wormy 
children,  is  owing  to  the  concomitant  deficiency  of   abforption 
from  the  cellular  membrane.     Salt  of  fteel,  or  the  rufl  of  it,  or 
filings  of  it,    with  bitters,  increafe  the  acrimony  of  the  bile  by 
promoting  the  abforption  of  its  aqueous  part ;  and  hence  deftroy 
worms,  as  well  by  their  immediate  a&ion  on  the  inteftines,  as 
on  the  worms  themfelves.     The  cure  is  facilitated  by  premifing 
a  purge  with  calomel.     See  Clafs  I.  2.3.  9. 

5.  The  chlorofis  is  another  difeafe  owing  to  the  deficient  ac- 
tion of  the  abforbents  of  the  liver,  and  perhaps  in  fome  degree 
alfo  to  that  of  the  fecretory  veflels,   or  glands,  which  compofe 
that  vifcus.     Of  this  the  want  of  the  catamenia,    which  is  gen- 
erally fuppofed  to  be  a  caufe,  is  only  a  fymptom  or  confequence. 
In  this  complaint  the  bile  is  deficient  perhaps  in  quantity,   but 
certainly  in  acrimony,  the  thinner  parts  not  being  abforbed  from 
it.     Now  as  the  bile  is  probably  of  great  confequence  in  the  pro- 
cefs  of  making  the  blood  ;    it  is   on  this  account  that  the  blood 
is  fo  deftitute  of  red  globules  ;    which  is  evinced  by  the  great 
palenefs  of  thefe  patients.     As  this  ferous  blood  mu!t  exert  lefs 
ftimulus  on  the  heart,   and  arteries,  the  pulfe  in   confequence 
becomes  quick  as  well  as  weak,  as  explained  in  Sect   XII.  i.  4. 

The  quicknefs  of  the  pulfe  is  frequently  fo  great  and  perma- 
nent, that  when  attended  by  an  accidental  cough,  the  difeafe 
may  be  miftaken  for  heftic  fever  ;  but  is  cured  by  chalybeates, 
and  bitters  exhibited  twice  a  day  ;  with  half  a  grain  of  opium, 
and  a  grain  of  aloe  every  night  ;  and  the  expefted  catamenia 
appears  in  confequence  of  a  reftoration  of  the  due  quantity  of 
red  blood.  This  and  the  two  former  articles  approach  to  the 
difeafe  termed -paralvfis  of  the  liver;  Seft.  XXX.  4. 


54  SORBENTIA.  ART.  IV.  2.  6. 6. 

6.  It  feerns  paradoxical,  that  the  fame  treatment  with  chalyb- 
eatcs,  bitters,  and  opiates,  which  produces  menilruation  in  chlo- 
rotic  patients,    fhould  reprefs  the  too  great  or  permanent  men- 
flruation,  which  occurs  in  weak  constitutions  at  the  time  of  life 
when  it  fhould  ceafe.     This  complaint  is  a  haemorrhage  owing 
to  the  debility  of  the  abforbent  power  of  the  veins,  and  belongs 
to  the  paragraph  on  venous  abforption   above  defcribed,  and  is 
thence  curable  by  chalybeates,  alum,  bitters,  and  particularly  by 
the  exhibition  of  a  grain  ot  opium  every  night  with  five  grains 
of  rhubarb. 

As  (foel  is  foluble  in  the  gaftric  acid,  perhaps  the  belt  way  of 
giving  it  may  be  in  fine  filings,  or  in  a  fteel-powder  prepared  in 
the  following  manner  :  diilblve  green  vitriol  in  water,  add  a  few 
bits  of  iron  to  the  folution,  to  precipitate  any  copper  which 
may  be  accidentally  in  it ;  precipitate  this  folution  by  fait  of  tar- 
tar, kalipreparatum.  Add  to  the  precipitate  two  or  three  times 
its  quantity  of  charcoal  powder,  mix  and  put  them  into  a  cruci- 
ble covered  with  a  tile,  and  give  them  a  red  heat  for  an  hour. 
An  impalpable  powder  of  iron  will  be  produced,  which  ought 
all  of  it  to  obey  the  magnet. 

7.  Metallic  falts  fupply  us  with  very  powerful  remedies  for 
promoting  abforption   in  dropfical  cafes  ;  which  frequently  are 
caufed  by  enlargement  of  the  liver.     Firft,  as  they  may  be  giv- 
en in  fuch  quantities  as  to  prove   ftrongly  cathartic,  of  which 
more  will  be  faid  in  the  article  on  invertentia  ;  and  then,  when 
their  purgative  quality  ceafes,   like  the  effect  of  rhubarb,    their 
abforbent  quality  continues  to  a£l.     The  falts  of  mercury,  filver, 
copper,  iron,  zinc,  antimony,  have  all  been  ufed  in  the  dropfy  ; 
either  fingly  for  the  former  purpofe,  or  united  with  bitters  for 
the  latter,  and  occafionally  with   moderate  but  repeated  opiates. 

8.  From  a  quarter  of  a  grain  to  half  a  grain  of  blue  vitriol 
given  every  four  or  fix  hour.-.,  is  faid  to  be  very  efficacious  in  ob- 
ilinate  intermittents  ;  which  alfo  frequently  arife  from  an  en- 
larged vifcus,  as  the  liver  or  fpleen,  and  are  thence  owing  to  the 
deficient  abforption  of  the  lymphatics  of  that  vifcus.     A  quarter 
of  a  grain  of  white  arfenic,  as  I  was  informed  by  a  furgeon  of  the 
army,  cures  a  quartan  ague  with  great  certainty,  if  it  be  given 
an  hour  before  the  expected   fit.      This  dofe  he   faid  was  for  a 
robufl  man,  perhaps  one  eighth  of  a  grain  might  be  given  and 
repeated  with  greater  fafety  and  equal  efficacy. 

Dr.  Fowler  has  given  many  fuccefsful  cafes  in  his  treatife 
on  this  fubje£t.  He  prepares  it  by  boiling  fixty-four  grains  of 
white  arfenic  in  a  Florence  flafk  along  with  as  much  pure  veget- 
able fixed  alkali  in  a  pint  of  diftilleci  water  till  they  are  diffolv- 
ed,  and  then  adding  as  much  diftilled  water  as  will  make  the 

whole 


ART.  IV.  2. 6.  9.  SORBENTIA.  55 

whole  exa6Uy  fixteen  ounces.  Hence  there  are  four  grains  of 
arfenic  in  every  ounce  of  the  folution.  This  (hould  be  put  into  a 
phial  of  fuch  a  fize  of  the  edge  of  its  aperture,  that  fixty  drops 
may  weigh  one  dram,  which  will  contain  half  a  grain  of  arfenic. 
To  children  from  two  years  old  to  four  he  gives  from  two  to  five 
drops  three  or  four  times  a  day-  From  five  years  old  to  feven, 
he  direcls  feven  or  eight  drops.  From  eight  years  old  to  twelve, 
he  directs  from  feven  to  ten  drops.  From  thirteen  years  old  to 
eighteen  he  diredls  from  ten  to  twelve  drops.  From  eighteen 
upwards,  twelve  drops.  In  fo  powerful  a  medicine  it  is  always 
prudent  to  begin  with  fmaller  doles,  and  gradually  to  increafe 
them. 

A  faturated  folution  of  arfenic  in  water  is  preferable  I  think 
to  the  above  operofe  preparation  of  it ;  as  no  error  can  happen 
in  weighing  the  ingredients,  and  it  more  certainly  therefore  pof- 
fefTes  an  uniform  ftrength.  Put  much  more  white  arfenic  re- 
duced to  powder  into  a  given  quantity  of  diftilled  water,  than 
can  be  difiblved  in  it.  Boil  it  (of  half  an  hour  in  a  Florence 
fiafk,  or  in  a  tin  fauce-pan  ;  let  it  (land  to  fubfide,  and  filter 
it  through  paper.  My  friend  Mr.  Greene,  a  furgeon  at  Bree- 
wood  in  Staffordfhire,  allured  me,  that  he  had  cured  in  one  fea- 
fon  agues  without  number  with  this  faturated  folution  ;  that  he 
found  ten  drops  from  a  two-ounce  vial  given  thrice  a  day  was 
a  full  dofe  for  a  grown  perfon,  but  that  he  generally  began 
with  five. 

9.  The  manner  in  which  arfenic  afts  in  curing  intermittent 
fevers  cannot  be  by  its  general  ftimulus,  becaufetno  intoxication 
or  heat  follows  the  ufe  of  it ;  nor  by  its  peculiar  ftimulus  on 
any  part  of  the  fecreting  fyftem,  fince  it  is  not  in  fmall  dofes 
fucceeded  by  any  increafed  evacuation,  or  heat,  and  muft  there- 
fore exert  its  power,  like  other  articles  of  the  ibrbentia,  on  the 
abforbent  fyftem.  In  what  manner  it  deftroys  life  fo  fuddenly 
is  difficult  to  underftand,  as  it  does  not  intoxicate  like  many 
vegetable  poifons,  nor  produce  fevers  like  contagious  matter. 
When  applied  externally  it  feems  chemically  to  deftroy  the  part 
like  other  cauftics.  Does  it  chemically  deftroy  the  ftomach, 
and  life  in  confequence  ?.  or  does  it  deftroy  the  adlion  of  the 
ftomach  by  its  too  great  ftimulus,  and  life  in  confequence  of  the 
fympathy  between  the  ftomach  and  the  heart  ?  This  laft  appears 
to  be  the  mod  probable  mode  of  its  operation. 

The  fuccefs  of  arfenic  in  the  cure  of  intermittent  fevers  I  fuf- 
pe6l  to  depend  on  its  (timulating  the  ftomach  into  ftronger  ac- 
tion, and  thus,  by  the  aflbciation  of  this  vifcus  with  the  heart 
and  arteries,  preventing  the  torpor,  of  any  part  of  the  fanguif- 

VOL.  I.  T  T  t  erotrs 


$6  SORBENTI A.  ART.  IV.  2. 6.  y . 

erous  fyftem.     I  was  led  to  this  conclufion  from  the  following 
confederations. 

Firft.  The  effects  of  arfenic  given  a  long  time  internally  in 
fraall  dofes,  or  when  ufed  in  larger  quantities  externally  feem 
to  be  fimilar  to  thofe  of  other  great  ftimuli,  as  of  wine  or  alco- 
hol. Thefe  are  a  bloated  countenance,  fwelled  legs,  hepatic  tu- 
mours, and  dropfy,  and  fometimes  eruption*  on  the  {kin.  The 
former  of  thefe  I  have  feen,  where  arfenic  has  been  ufed  external- 
ly for  curing  the  itch  ;  and  the  latter  appears  in  evidence  in  the 
famous  trial  of  Mifs  Blandy  at  Chelmsford, about  forty  years  ago. 

Secondly.  I  faw  an  ague  cured  by  arfenic  in  a  child,  who 
had  in  vain  previoufly  taken  a  very  large  quantity  of  bark  with 
great  regularity.  And  another  cafe  of  a  young  officer,  who  had 
lived  intemperately,  and  laboured  under  an  intermittent  fever, 
and  had  taken  the  bark  repeatedly  in  confiderable  quantities, 
with  a  grain  of  opium  at  night,  and  though  the  paroxyfms  had 
been  thrice  thus  for  a  time  prevented,  they  recurred  in  about  a 
week.  On  taking  five  drops  of  a  faturated  folution  of  arfenic 
thrice  a  day  the  paroxyfms  ceafed,  and  returned  no  more,  and 
at  the  fame  time  his  appetite  became  much  improved. 

Thirdly.  A  gentleman  about  fixty-five  years  of  age  had  for 
about  ten  years  been  fubject  to  an  intermittent  pulfe,  and  to 
frequent  palpitations  of  his  heart.  Lately  the  palpitations 
feemed  to  obferve  irregular  periods,  but  the  intermiffion  of  eve- 
ry third  or  fourth  pulfation  was  almoft  perpetual.  On  giving 
him  four  drops  of  a  faturated  folution  of  arfenic  from  a  two- 
ounce  phial  almoft  every  four  hours  for  one  day,  not  only  the 
palpitation  did  not  return,  but  the  intermiffion  ceafed  entirely, 
and  did  not  return  fo  long  as  he  took  the  medicine,  which  was 
three  or  four  days. 

Now  as  when  the  ftomach  has  its  action  much  weakened  by 
an  over-dofe  of  digitalis,  the  pulfe  is  liable  to  intermit,  this  evin- 
ces a  direct  fymparhy  between  thefe  parts  of  the  fyftem  ;  and 
as  I  have  repeatedly  obferved,  that  when  the  pulfe  begins  to  in- 
termit in  elderly  people,  that  an  eructation  from  the  ftomach, 
voluntarily  produced,  will  prevent  the  threatened  flop  of  the 
heart ;  I  am  induced  to  think  that  the  torpid  ftate  of  the  ftom- 
ach, at  the  inftant  of  the  production  of  air  occafioned  by  its 
weak  action,  caufed  the  intermiffion  of  the  pulfe.  And  that 
arfenic  in  this  cafe,  as  well  as  in  the  cafes  of  agues  above  men- 
tioned, produced  its  effects  by  ftimulating  the  ftomach  into  more 
powerful  action  ;  and  that  the  equality  of  the  motions  of  the 
heart  was  thus  reftored  by  increafing  the  excitement  of  the  fen- 
forial  power  of  aflbpiation.  See  Sect.  XXIV.  17.  Clafs  IV 
a.  i.  18. 

Arfenic 


ART.  VI.  a.  7.  i.  SORBENTIA.  57 

Arfenic  has  lately  been  recommended  in  the  hooping  cough, 
tuflis  convulfiva,  by  Mr.  Simmons,  furgeon  of  Mancheiter, 
which  he  aflerts  to  be  attended  with  the  moil  falutary  effects, 
moderating  the  difeafe  in  a  few  days,  and  curing  it  generally  in 
a  fortnight.  He  has  given  it  to  children  of  a  year  old  with  fafe- 
ty,  in  the  dofes  recommended  by  Dr.  Fowler,  whofe  folution 
he  ufed,  but  feems  to  have  ufed  venefection  and  emetics  occa- 
fionally,  and  recommends,  after  the  folution  has  been  omitted 
for  a  week,  to  repeat  it,  to  prevent  a  relapfe.  Annals  of  Med- 
icine, 1797. 

TO  Where  arfcnic  has  been  given  as  a  poifon,  it  may  be  dif- 
covered  in  the  contents  of  the  ftomach  by  the  fmell  like  garlic, 
when  a  few  grains  of  it  are  thrown  on  red-hot  iron.  2.  If  a 
few  grains  are  placed  between  two  plates  of  copper,  and  fub~ 
jefted  to  a  red  heat,  the  copper  becomes  whitened.  3.  Dif- 
folve  arfenic  in  water  along  with  vegetable  alkali,  add  to  this  a 
folution  of  blue  vitriol  in  water,  and  the  mixture  becomes  of  a 
fine  "green,  which  gradually  precipitates,  as  difcovered  by  Berg- 
man. 4.  Where  the  quantity  is  fufficient,  fome  wheat  may  be 
deeped  in  a  folution  of  it,  which  given  to  fparrows  or  chickens 
will  deftroy  them. 

VII.  i .  Abforption  of  the  matter  from  venereal  ulcers.  No 
ulcer  can  heal,  unlefs  the  abforption  from  it  is  as  great  as  the 
depofition  in  it.  The  preparations  or  oxydes  of  mercury  in  the 
cure  of  the  venereal  difeafe  feem  to  acT:  by  their  increasing  the 
abforption  of  the  matter  in  the  ulcers  it  occalions  ;  and  that 
whether  they  are  taken  into  the  ftomach,  or  applied  on  the  fkin, 
or  on  the  furface  of  the  ulcers.  And  this  in  the  fame  manner 
as  fugar  of  lead,  or  other  metallic  oxydes,  promote  fo  rapidly 
the  healing  of  other  ulcers  by  their  external  application  ;  and 
probably  when  taken  internally,  as  ruft  of  iron  given  to  children 
affedted  with  fcrofulous  ulcers  contribute  to  heal  them,  and  fo- 
lutions  of  lead  were  once  famous  in  phthifis. 

The  matter  depofited  in  large  abfcefTes  does  not  occafion  heo 
tic  fever,  till  it  has  become  oxygenated  by  being  expofed  to  the 
open  air,  or  to  the  air  through  a  moift  membrane  ;  the  fame 
feems  to  happen  to  other  kinds  of  matter,  which  produce  fever, 
or  which  occafion  fpreading  ulcers,  and  are  thence  termed  con- 
tagious. See  Clafs  II.  i,  3.  II.  i.  5.  II.  i.  6.  6.  This  may 
perhaps  occur  from  thefe  matters  not  being  generally  abforbed, 
till  they  become  oxygenated  ;  and  that  it  is  the  ftimulus  of  the 
acid  thus  formed  by  their  union  with  oxygen,  which  occafions 
their  abforption  into  the  circulation,  and  the  fever,  which  they 
then  produce.  For  though  collections  of  matter,  and  milk,  and 
mucus,  are  fometiraes  fuddenly  abforbed  during  the  aclion  of 

emetics 


$8  SORBENTIA.  ART. IV.  2.  7.  2, 

emetics  or  in  fea-ficknefs,  they  are  probably  eliminated  from  the 
body  without  entering  the  circulation  ;  that  is,  they  are  taken 
up  by  the  increafed  action  of  one  lymphatic  branch,  and  evacu- 
ated by  the  inverted  action  of  fome  other  lymphatic  branch,  and 
thus  carried  off  by  ftool  or  urine. 

2.  But  as  the  matter  in  large  abfcefles  is  in  general  not  ab- 
forbed,  till  it  becomes  by  fome  means  expofed  to  air,  there  is 
reafon  to  conclude,  that  the  (limulus  of  this  new  combination 
of  the  matter  with  oxygen  occafions  its  abforption  ;  and  that 
hence  the  abforption  of  matter  in  ulcers  of  all  kinds,  is  ftill  more 
powerfully  affected  by  the  external  application  or  internal  ufe 
of  metallic  oxydes  j  which  are  alfo  acids  confiding  of  the  metal 
united  with  oxygen  ;  and  lallly,  becaufe  venereal  ulcers,  and 
thofe  of  itch,  and  tinea,  will  not  heal  without  fome  ftimulant 
application  \  that  is,  the  fecretion  of  matter  in  them  continues 
to  be  greater,  than  the  abforption  of  it  j  and  the  ulcers  at  the 
fame  time  continue  to  enlarge,  by  the  contagion  affecting  the 
edges  of  them  ;  that  is,  by  the  {limulus  of  the  oxygenated  mat- 
ter ftimulated  the  capillary  veflels  in  its  vicinity  into  actions 
fimilar  to  thofe  of  the  ulcer,  which  produces  it. 

This  effect  of  the  oxydes  of  mercury  occurs,  whether  faliva- 
tion  attends  its  ufe  not.  Salivation  is  much  forwarded  by 
external  warmth,  when  mercury  is  given  to  promote  this  fecre- 
tion ;  but  as  the  cure  of  venereal  complaints  depends  on  its  ab- 
forbent  quality,  the  act  of  falivation  is  not  neceflary  nor  ufeful. 
A  quarter  of  a  grain  of  good  corrofive  fublimate  twice  a  day  will 
feldom  fail  of  curing  the  mod  confirmed  pox  ;  and  will  as 
feldom  falivate,  if  the  patient  be  kept  cool  A  quarter  of  a 
jrain  thrice  a  day  I  believe  to  be  infallible,  if  it  be  good  fub- 
limate. 

Mercury  alone  when  fwallowed  does  not  act  beyond  the  in- 
teftines  ;  its  active  preparations  are  the  falts  formed  by  its  union 
with  the  various  acids,  as  mentioned  in  the  catalogue.  Its  union 
with  the  vegetable  acid,  when  triturated  with  manna,  is  faid  to 
compofe  Keyfer'sPill.  Triturated  with  gum  arabic  it  is  much 
recommended  by  Plenck  ;  and  triturated  with  fugar  and  a  little 
effential  oil,  as  directed  in  a  former  Edinburgh  Difpenfatory,  it 
probably  forms  fome  of  the  fyrups  fold  as  noftrums. 

United  with  fulphur  it  feldom  enters  the  circulation,  as  when 
cinnabar,  or  aethiops  mineral,  is  taken  inwardly.  But  united 
with  fat  and  rubbed  on  the  fkin,  it  is  readily  abforbed.  I  know- 
not  whether  it  can  be  united  to  charcoal,  nor  whether  it  has 
been  given  internally  when  united  with  animal  fat ;  if  fix  grains 
only  of  fulphur  be  added  to  two  ounces  of  hog's  fat  and  fix 

drachms 


ART.  IV.  2.  8.  i.  SORBENTIA.  55 

drachms  of  mercury,   they  are  faid  to  unite  with  much  lefs  la- 
bour of  trituration,  than  the  hog's  fat  and  mercury  alone. 

VIII.  i.  Abforptions  in  general  are  increafed  by  inanition  ; 
hence  the  ufe  of  evacuations  in  the  cure  of  ulcers.     Dr.  Jurin 
abforbed    in  one  night,  after   a  day's  abftinence   and  exercife, 
eighteen  ounces  from  the  atmofphere  in  his  chamber  ;  and  eve- 
ry one  muft  have  obferved,   how  foon  his  fheets  became  dry, 
after  having  been  moiftened  by  fweat,  if  he  throws  off  part  of 
the  bed- clothes  to  cool  himfelf ;  which  is  owing  to  the  increafed 
cutaneous  .abforption  after  the  evacuation  by  previous  fweat. 

2.  Now  as  opium  is  an  univerfal  ftimulus,  as  explained  in 
the  article  of  Incitantia,  it  muft  ftimulate  into  increafed  action 
both  the  fecretory  fyftem,  and  the  abforbent  one  ;  but  after  re- 
peated evacuation  by  venefe&ion,  and  cathartics,  the  abforbent 
fyftem  is  already  inclined  to  aft  more  powerfully  ;  as  the  blood- 
veflels  being  lefs  diftended,  there  is  lefs  refiftance  to  the  progrefs 
of  the  abforbed  fluids  into  them.  Hence  after  evacuations  opi- 
um promotes  abforption,  if  given  in  fmall  dofes,  much  more 
than  it  promotes  fecretion  5  and  is  thus  eminently  of  fervice  at 
the  end  of  inflammations,  as  in  pleurify,  or  peripnuemony,  in 
the  dofe  of  four  or  five  drops  of  the  tincture,  given  before  the 
accefs  of  the  evening  paroxyfm  ;  which  I  have  feen  fucceed 
even  when  the  rifus  fardonicus  has  exifted.  Some  convulfions 
may  originate  in  the  want  of  the  abforption  of  fome  acrid  fecre- 
tion, which  occafions  pain  ;  hence  thefe  difeafes  are  fo  much 
more  certainly  relieved  by  opium  after  venefection  or  other 
evacuations. 

IX.  i.  Abforption  is  increafed  by  the  calces  or  folutions  of 
mercury,  lead,  zinc,  copper,  iron,  externally  applied  ;  and  by 
arfenic,  and  by  fulphur,  and  by  the  application  of  bitter  vegeta- 
bles in  fine  powder.     Thus  an  ointment  confiding  of  mercury 
and  hog's  fat  rubbed  on  the  (kin  cures  venereal  ulcers ;  and  ma- 
ny kinds  of  herpetic  eruptions  are  removed  by  an  ointment  cori- 
fifting  of  fixty  grains  of  white  precipitate  of   mercury  and  ah 
ounce  of  hog's  fat. 

2.  The  tumours  about  the  necks  of  young  people  are  often 
produced  by  the  abforption  of  a  faline  or  acrid  material,  which 
has  been  depofited  from  eruptions  behind  the  ears,  owing  to  de- 
ficient abforption  in  the  furface  of  the  ulcer,  but  which  on  run- 
ning down  on  the  Ikin  below  becomes  abforbed,  and  fwells  the 
lymphatic  glands  of  the  neck  ;  as  the  variolous  matter,  when 
inferted  into  the  arm,  fwells  the  gland  of  the  axilla.  Some- 
times the  perfpirative  matter  produced  behind  the  ears  becomes 
putrid  from  the  want  of  daily  warning  them,  and  may  alfo  caufc 
by  its  abforption  the  tumours  of  the  lymphatics  of  the  neck, 

In 


&>  SORBENTIA.  ART.  IV.  2. 9.  3. 

In  the  former  cafe  the  application  of  a  cerate  of  lapis  calamina- 
ris,  or  of  ceruffa  in  dry  powder,  or  of  rags  dipped  in  a  folution 
of  fugar  of  lead,  increafes  the  abforption  in  the  ulcers,  and  pre- 
vents the  effufion  of  the  faline  part  of  the  fecreted  material. 
The  latter  is  to  be  prevented  by  cleanlinefs. 

After  the  eruptions  or  uicers  are  healed  a  folution  of  corrofive 
fublimate  of  one  grain  to  an  ounce  of  water  applied  for  fome 
weeks  behind  the  ear,  and  among  ft  the  roots  of  the  hair  on  one 
fide  of  the  head,  where  the  mouths  of  the  lymphatics  of  the 
neck  open  themfelves,  frequently  removes  thefe  tumours. 

3.  Linen  rags  moiftened  with  a  folution  of  half  ar^  ounce  of 
fugar  of  lead  to  a  pint  of  water  applied  on  the  eryfipelas  on  ana- 
farcous  legs,  which  have  a  tendency  to  mortification,  is  more 
efficacious  than  other  applications.  White  vitriol  fix  grains 
diflblved  in  one  ounce  of  rofe  water  removes  inflammations  of 
the  eyes  after  evacuation  more  certainly  than  folutions  of  lead. 
Blue  vitriol  two  or  three  grains  diflblved  in  an  ounce  of  water 
cures  ulcers  in  the  mouth,  and  other  mucous  membranes,  and 
a  iolution  of  arfenic  externally  applied  cures  the  itch,  but  re- 
quires great  caution  in  the  ufe  of  it.  See  Clafs  II.  r.  5.  6. 

A  feeble  old  man  with  fwelled  legs  had  an  eryfipelas  on  both 
of  them  ;  to  one  of  thefe  legs  a  fine  powder  of  Peruvian  bark 
was  applied  dry,  and  renewed  twice  a  day  •,  on  the  other  linen 
rags  moiftened  with  a  folution  of  faccharum  faturni  were  appli- 
ed, and  renewed  twice  a  day  ;  and  it  was  obferved,  that  the 
latter  healed  much  fooner  than  the  former. 

As  the  external  application  of  calx  of  lead  Simulates  inflam- 
ed parts  very  violently,  if  it  be  applied  too  early,  before  the 
vefiels  are  emptied  by  evacuations,  or  by  the  continuance  of  the 
difeafe,  it  is  liable  to  increafe  the  inflammation,  or  to  induce 
mortification,  as  in  ophthalmy  ;  and  in  a  cafe,  which  was  re- 
lated to  me  of  a  perfon  who  much  pricked  his  legs  amongfl 
gorfe,  which,  on  the  application  of  Goulard's  folution  of  lead, 
mortified  with  extenfive  floughs.  But  where  the  fyftem  is  pre- 
vioufly  emptied,  there  is  lefs  refiftance  to  the  progrefs  of  abforb- 
ed  fluids  ;  and  the  ftimulus  of  lead  then  increafes  the  a&ion 
of  the  abforbent  fyftem  more  than  the  fecerning  fyftem,  and  the 
inflamed  part  prefently  difappears. 

4.  Bitter  vegetables,  as  the  Peruvian  bark,  quilted  between 
two  (hirts,  or  ftrewed  in  their  beds,  will  cure  the  ague  in  chil- 
dren fometimes.  Iron  in  folution,  and  fome  bitter  extract,  as  in 
the  form  of  ink,  will  cure  one  kind  of  herpes  called  the  ringworm. 
And  I  have  feen  feven  parts  of  bark  in  fine  powder  mixed  with 
one  part  of  cerufe,  or  white  lead,  in  fine  powder,  applied  dry  to 
fcrofulus  ulcers,  and  renewed  daily,  with  great  advantage. 

5.  To 


ART.  IV.  2.  9.  5.  SORBENTIA.  61 

5.  To  thefe  (hould  be  added  ele&ric  fparks  and  (hocks, 
which  promote  the  abforption  of  the  veflels  in  inflamed  eyes  of 
fcrofulous  children  ;  and  difperfe,or  bring  to  fuppuration,  fcrof- 
ulous  tumours  about  the  neck.  For  this  laft  purpoie  fmart 
(hocks  fhould  be  pafTed  through  the  tumours  only,  by  ericlofmg 
them  between  two  brafs  knobs  communicating  with  the  external 
and  internal  coating  of  a  charged  phial.  See  Art.  II.  2.  2.  2. 

X.  i.  Bandages  increafe  abforption,  if  they  are  made  to  fit 
nicely  on  the  part ;  for  which  purpofe  it  is  neceffary  to  fpread 
fome  moderately  adhefive  plafter  on  the  bandage,  and  to  cut  it 
into  tails,  or  into  (breads  two  inches  wide  ;  the  ends  are  to  be 
wrapped  over  each  other ;  and  it  mud  be  applied  when  the  part 
is  leaft  tumid,  as  in  the  morning  before  the  patient  rifes,  if  on 
the  lower  extremities.  The  emplaflrum  de  minio  made  to  cov- 
er the  whole  of  a  f welled  leg  in  this  manner,  whether  the  fweil- 
ing  is  hard,  which  is  ufually  termed-fcorbutic  ;  or  more  eafily 
compreiTible,  as  in  anafarca,  reduces  the  limb  in  two  or  three 
days  to  its  natural  fize  ;  for  this  purpofe  I  have  fometimes  ufed 
carpenter's  glue,  mixed  with  one  twentieth  part  of  honey  to 
prevent  its  becoming  too  hard,  inftead  of  a  refmous  plafter  ;  but 
the  minium  plafter  of  the  (hops  is  in  general  to  be  preferred, 
Nothing  fo  much  facilitates  the  cure  of  ulcers  in  the  legs,  as 
covering  the  whole  limb  from  the  toes  to  the  knee  with  fuch  a 
plafter  bandage  •,  which  increafes  the  power  of  abforption  in  the 
furface  of  the  fore. 

2.  The  lymph  is  carried  along  the  abforbent  veflels,  which  are 
replete  with  valves,  by  the  intermitted  preflure  of  the  arteries  in 
their  neighbourhood.  Now  if  the  external  (kin  of  the  limb  be  lax, 
it  rifes,  and  gives  way  to  the  preflure  of  the  arteries  at  every  pul- 
fation  ;  and  thence  the  lymphatic  veffels  are  fubject  to  the  pref- 
fure  of  but  half  the  arterial  force.  But  when  the  external  fkin 
is  tightened  by  the  furrounding  bandage,  and  thence  is  not  ele- 
vated by  the  arterial  diaftole,  the  whole  of  this  power  is  exerted 
in  comprefling  the  lymphatic  veflels,  and  carrying  on  the  lymph 
already  abforbed  ;  and  thence  the  abforbent  power  is  fo  amaz- 
ingly increafed  by  bandage  nicely  applied.  Pains  are  fomeiimes 
left  in  the  flefhy  parts  of  the  thighs  or  arms,  after  the  inflamma- 
tion is  gone,  in  the  acute  rheumatifm,  or  after  the  patient  is  too 
weak  for  further  evacuation  •,  in  this  cafe  after  internal  abforbent 
medicines,  as  the  bark,  and  opiates,  have  been  ufed  in  vain,  I 
have  fuccefsfully  applied  a  plafter-bandage,  as  above  defcribed, 
fo  as  to  comprefs  the  pained  part. 

Since  the  above  was  written,  Mr.  Baynton,  an  ingenious  fur- 
geon  of  Briftol,  has  publifhed  "  A  Method  of  Treating  Ulcers 
of  the  Legs,"  fold  by  Robinfon,  London.  In  which  he  endeav- 
ours 


62  SORBENTIA.  ART.  IV.  2.  11.  r. 

ours  to  bring  the  lips  of  thofe  ulcers  nearer  together  by  means 
of  flips  of  adhefive  plafter,  as  above  defcribed  ;  which  feems  to 
have  been  attended  with  great  fuccefs,  without  confinement  of 
the  patient.  See  Sett.  XXXIII.  3.  2. 

But  when  flips  of  adhefive  plafter  are  put  over  a  wound  fo  as 
to  bring  the  edges  of  it  together  nearly,  or  quite,  into  contact 
with  each  other,  the  part  is  at  the  fame  time  covered,  as  the  flips 
of  adhefive  plaiter  are  applied,  from  the  eye  of  the  furgeon  I 
have  therefore  advifed  two  tin  plates  a  little  longer  than  the 
wound,  and  about  half  an  inch  broad,  to  be  faftened  to  the  ends 
of  the  pieces  of  adhefive  plafter,  and  applied  one  on  each  lip  o£ 
the  wound  or  ulcer  ;  and  then  by  a  narrow  flip  of  adhefive  plaf- 
ter applied  at  each  end  of  thefe  tins,  they  may  be  drawn  togeth- 
er, and  the  whole  lips  of  the  wound  may  be  feen  at  the  fame 
time  by  the  furgeon  ;  and  then  a  comprefs  of  thin  lead,  or  of 
linen,  may  be  applied  by  other  ftrips  of  plafter  fo  as  to  heal  re- 
cent wounds,  and  even  ulcers,  without  fcarcely  any  unevenefs 
or  width  of  the  fear. 

XL  i.  We  ihall  conclude  by  obferving,  that  the  forbentia 
ftrengthen  the  whole  habit  by  preventing  the  efcape  of  the  fluid 
part  of  the  fecretions  out  of  the  body,  before  it  has  given  up  as 
much  nourifhment,  as  it  is  capable  ;  as  the  liquid  part  of  the  fe- 
cretion  of  urine,  fweat,  faliva,  and  of  all  other  fecretions,  which 
are  poured  into  receptacles.  Hence  they  have  been  faid  to 
brace  the  body,  and  been  called  tonics,  which  are  mechanical 
terms  not  applicable  to  the  living  bodies  of  animals  j  as  explain- 
ed in  Sea.  XXXII.  3.  2. 

2.  A  continued  ufe  of  bitter  medicines  for  years  together,  as 
of  Portland's  powder,  or  of  the  bark,  is  fuppofed  to  induce  apo- 
plexy, or  other  fatal  difeafes  Two  cafes  of  this  kind  have  fall- 
en under  my  obfervation ;  the  patients  were  both  rather  intem- 
perate in  refpedt  to  the  ufe  of  fermented  liquors,  and  one  of 
them  had  been  previoufly  fubjecl:  to  the  gout.  As  I  believe  the 
gout  generally  originates  from  a  torpor  of  the  liver,  which,  in- 
ftead  of  being  fucceeded  by  an  inflammation  of  it,  is  fucceeded 
by  an  inflammation  of  fome  of  the  joints  ;  or  by  a  pimpled  face, 
which  is  another  mode,  by  which  the  difeafe  of  the  iiver  is  ter- 
minated :  I  conceive,  that  the  daily  ufe  of  bitter  medicines  had 
in  thefe  patients  prevented  the  removal  of  a  gouty  inflammation 
from  the  liver  to  the  membranes  of  the  joints  of  the  extremities, 
or  to  the  (kin  of  the  face,  by  preventing  the  neceflfary  torpor 
of  thefe  parts  previous  to  the  inflammation  of  them  ;  in  the  lame 
manner  as  cold  fits  of  fever  are  prevented  by  the  fame  medicines ; 
and,  as  I  believe,  the  returns  of  the  gout  have  fome  times  for 
two  or  three  years  been  prevented  by  them. 

One 


ART.  IV.  3.  i.  SORBENTIA.  63 

One  of  thefe  patients  died  of  the  apoplexy  in  a  few  hours  ; 
and  the  other  of  inflammation  of  the  liver,  which  I  believe 
was  called  the  gout,  and  in  confequence  was  nor  treated  by  ven- 
cfeclion,  and  other  evacuations.  Hence  it  appears,  that  the 
daily  ufe  of  hop  in  our  malt  liquor  muft  add  to  the  noxious  qual- 
ity of  the  fpirit  in  it,  when  taken  to  excefs,  and  contribute  to 
the  production  of  apoplexy,  or  inflammation  of  the  liver. 

Ill,  CATALOGUE  OF  THE  SORBENTIA. 

I.  Sorbentia  affecting  the  ftin. 

1.  Acid  of  vitriol,  of  fea- fait,  lemons,  floes,  prunus  fpi- 
nofa,  crabs,  pyrus,  quince,  pyruscydonia,  opium, 

2.  Externally  calx  of  zinc,  of  lead,  or  of  mercury. 

II.  Sorbentia  affecling  the  mucous  membranes. 

1.  Juice  of  floes,  crabs,  Peruvian  bark,  cinchona,  opium, 

2.  Externally  blue  vitriol. 

III.  Sorbentia  affecling  the  cellular  membrane. 

1.  Peruvian  bark,  wormwood,   artemifia  maritima,  arte- 
mifia    abfynthium,    worm-feed,  artemifia  fantonicum, 
chamomile,  anihemis  nobilis,  tanfey,  tanacetum,  bog- 
bean,  menyanthes  trifoliata,  centaury,  gentiana  centau- 
rium,  gentian,  gentiana  lutea,  artichoke-leaves,  cynara 
fcolymus,  hop,    humulus  lupulus,  falix  caprea,  geum 
urbanum,  datifca  cannabina. 

2.  Orange-peel,  cinnamon,  nutmeg,  mace. 
3    Vomits,  fquill,  digitalis,  tobacco. 

4.  Bath  of  warm  air,  of  fleam. 
IV-  Sorbentia  affecling  the  veins. 

1.  Water-crefs,  fifymbrium  nafturtium  aquaticum,  muf- 
tard,  finapis,  fcurvy-grafs,  cochlearia  hortenfis,  horfe- 
radifh,    cochlearia    armoracia    cuckoo-flower,  carda- 
mine,  dog's- grafs,    dandelion,  leontodon,  taraxacon, 
cellery,  apium,  cabbage,  braflica. 

2.  Chalybeates,  bitters,  and  opium,  after  fufficient  evac- 
uation. 

3.  Externally  vinegar,  friclion,  eleclricity. 
V.  Sorbentia  affecling  the  inteftines. 

1.  Rhubarb,  rheum  paimatum,  oak-galls,  galliequercinse, 
tormemilla  erecla,    cinquefoil,  potentilla,    red-rofes, 
uva  urfi,  fimarouba. 

2.  Logwood,     hsematoxylum,     campechianum,     fuccus 
acacise,  dragon's  blood,  terra  japonica,  mimofa  catechu. 

3.  Alum,  earthof  alum,  Armenian  bole,  chalk,  creta,  crabV 
VOL.  I.  U  u  u  claws, 


<J4  SORBENTIA.  ART.  IV.  3.  <f. 

claws,  chelx  cancrorum,  white  clay,  cimolia,  calcined 
hartftiorn,  cornu  cervi  calcinatum,  bone-afhes. 

VI.  Sorbentia  afle£ting  the  liver,  ftomach,  and  other  vifcera. 
Ruft  of  iron,  filings  of  iron,  fait  of  fteel,  fal  raartis, 
blue  vitriol,  white  vitriol,  calomel,  emetic  tartar,  fugar 
of  lead,  white  arfenic. 

VIL  Sorbentia  affecling  venereal  ulcers.  Mercury  diflblved 
or  corroded  by  the  following  acids : 

1.  Diflblved  in   vitriolic  acid,  called  turpeth  mineral,  or 
hydrargyrus  vitriolatus. 

2.  Diflblved  in  nitrous  acid,  called  hydrargyrus  nitratus 
ruber. 

3.  Diflblved  in  muriatic   acid,  mercurius  corrofivus  fub- 
Kmatus,  or  hydrargyrus  muriatus. 

4.  Corroded  by  muriatic  acid.     Calomel. 

5.  Precipitated  from  muriatic  acid,  mercurius  precipita- 
tus  albus,  calx  hydrargyri  alba. 

6.  Corroded  by  carbonic  acid  ?     The  black  powder  on 
crude  mercury. 

7.  Calcined,  or  united  with  oxgen. 

3.  United  with  animal  fat,  mercurial  ointment. 
9.  United  with  fulphur.     Cinnabar. 

10.  Partially  united  with  fulphur.     j-Ethiops  mineral. 

11.  Divided  by  calcareous  earth.  Hydrargyrus  cum  creta. 

12.  Divided  by  vegetable  mucilage,  by  fugar,  by  balfams. 
yill.  Sorbentia    affecting   the  whole  fyftem.     Evacuations 

by  venefe&ion  and  catharfis,  and  then  the  exhibition 
of  opium. 

IX.  Sorbentia  externally  applied. 

1.  Solutions  of  mercury,  lead,  zinc,  copper,  iron,  arfen- 
ic ;  or  metallic   calces  applied  in  dry  powder,  as  ce- 
rufla,  lapis  calaminaris. 

2.  Bitter   vegetables    in  deco&ions  and  in  dry  powders, 
applied  externally,  as  Peruvian  bark,  oak  bark,  leaves 
of  wormwood,  of  tanfey,  chamomile  flowers  or  leaves. 

3.  Eleftric  fparks,  or  (hocks. 

X.  Bandage   fpread  with  emplaftrum  e  minio,  or  with  car- 

penter's glue   mixed  with  one  twentieth  part  of  honey. 

XI.  Portland's  powder,  its  continued  ufe  pernicious,  and  of 

hops  in  beer. 


ART 


ART.  V.  i.  i.  INVERTENTIA  65 

ART.  V. 
INVERTENTIA. 

I.  THOSE  THINGS,  which  invert  the  natural  order  of  the  fuc 
ceflive  irritative  motions,  are  termed  invertentia. 

1.  Emetics  invert  the  motions  of  the  flomach,  duodenum, 
and  cefophagus. 

2.  Violent  cathartics  invert  the  motions  of  the  ladeals,  and 
mteftinal  lymphatics. 

3.  Violent  errhines  invert  the  nafal  lymphatics,  and  thofe  of 
the^  frontal  and    maxillary  fmufes.     And  medicines  producing 
naufea,  invert  the    motions  of  the  lymphatics  about  the  fauces. 

4.  Medicines  producing  much  pale  urine,  as  a  certain  quan- 
tity of    alcohol,  invert  the  motions  of  the  urinary  ablbrbents  ;  if 
the  dofe  of  alcohol  is  greater,  it  inverts  the  ft omach,  producing 
the  drunken  ficknefs. 

5.  Medicines  producing  cold  fweats,  palpitatron  of  the  heart, 
globushyflericus;  as  violent  evacuations,  fome  poifons,  fear,  anx- 
iety, act  by  inverting  the  natural  order  of  the  vafcular  motions, 

II.   OBSERVATIONS  ON  THE  INVERTENTIA. 

1.  i.  The  aclion  of  vomiting  feems  originally  to  have  been 
occafioned  by  difagreeable  fen  fation  from  the  diflentkm  or  acri- 
mony of  the  aliment  -,  in  the  fame  manner  as  when  any  difguft- 
ful  material  is  taken  into  the  mouth,  as  a  bitter  drug,  and  is  re- 
jected by  the   retrograde    motions  of   the  tongue  and  lips  ;    ar> 
explained  in  Clafs  IV.  i.  i.  2.  and  mentioned  in  Scft.  XXXV 
1.3.     Or  the  difagreeabl-e  fen  fation  may  thus  excite  the  powei 
of  volition,  which  may  alfo  contribute  to  the  retrograde  a£Hon" 
of  the  flomach  and  cefophagus,  us  when  cows  bring  up  the  con- 
tents of  their  firfl  ftomach  to  remafticate  it.     To  either  of  thefr 
is  to  be  attributed  the  action  of  mild  emetics,  which  foon  ceafe 
to  operate,    and   leave  the  flomach  Wronger,  or  more  irritable> 
after  their  operation  ;   owing  to  the  accumulation  of  the  fenfo- 
rial   power   of  irritation  during   its  torpid  or  inverted  adlion- 
Such  appears  to  be  the  operation  of  ipecacuanha,  or  of  .antimo- 

"nium  tartarizatum,  in  fmall  dofes. 

2.  But  there  is  reaibn  to     believe,  that  the  ftronger  emetics, 
as  digitalis,  firfl   ilimulate  the  abforbent  vefTels  of  the  flomach 
into  greater  aclion  ;   and  that  the  inverted  motions  of  thefe  ab~ 
forbems  next  occur,  pouring  the  lymph,  iately  ta"ken  up,  or  ob- 
tained from  other   lymphatic  branches,  into  the  flomach  ;   the 
quantity  of  whichsin  fome  difeafes,  as  in  the  cholera  morbus,io 

inconceivable. 


.06  INVERTENTIA.  ART  V.  2.  i .  2. 

inconceivable.  This  inverted  motion,  firft  of  the  abforbents  of 
the  ftomach,  and  afterwards  of  the  ftomach  itfelf,  feems  to  orig- 
inate from  the  exhauftion  or  debility,  which  fucceeds  the  un- 
natural degree  of  action,  into  which  they  had  been  previouily 
ftimulated  An  unufual  defect  of  ftimulus,  as  of  food  without 
fpice  or  wine  in  the  ftomachs  of  thofe,  who  have  been  much 
accuftomed  to  fpice  or  wine,  will  induce  (icknefs  of  vomiting  -9 
in  this  cafe  the  defective  energy  of  the  ftomach  is  owing  to 
defect  of  accuftomed  ftimulus  ;  while  the  action  of  vomiting 
from  digitalis  is  owing  to  a  deficiency  of  fenforial  power,  which 
is  previoufly  exhaufted  by  theexcefs  of  its  ftimulus.  See  Sect. 
XXXV  1.3.  and  Clafs  IV.  i.  i.  2. 

For  firft,  no  increafe  of  heat  arifesfrom  this  action  of  vomit- 
ing i  which  always  occurs,  when  the  fecerning  fyftem  is  ftimu- 
lated into  action.  Secondly,  the  motions  of  the  abforbent  vef- 
fels  are  as  liable  to  inverfion  as  the  ftomach  itfelf  ;  which  laft, 
with  the  oefophagus,  may  be  confidered  as  the  abforbent  mouth 
and  belly  of  that  great  gland,  the  inteftinal  canal.  Thirdly, 
the  clafs  of  forbentia,  as  bitters  and  metallic  falts,  given  in  large 
dofes,  become  invertentia,  and  vomit,  or  purge.  And  laftly, 
the  ficknefs  and  vomiting  induced  by  large  potarions  of  wine, 
or  opium,  does  not  occur  till  next  day  in  fome  people,  in  none 
till  fome  time  after  their  ingurgitation.  And  tincture  of  digi- 
talis in  the  dofe  of  30  or  60  drops,  though  applied  in  folution,  is 
a  confiderable  time  before  it  produces  its  effect  5  though  vomiting 
is  inftantaneoufly  induced  by  a  nafeous  idea,  or  a  naufeoustafte 
in  the  mouth.  At  the  fame  time  there  feern  to  be  fome  mate- 
rials whichcan  immediately  ftimulate  the  ftomach  into  fuch  pow- 
erful action,  as  to  be  immediately  fucceeded  by  paralyfis  of  it, 
and  confequent  continued  fever,  or  immediate  death  5  and  this 
without  exciting  fenfation,  that  is,  without  our  perceiving  it. 
Of  thefe  are  the  contagious  matter  of  fome  fevers  fwallo wed 
with  the  faliva,  and  probably  a  few  grains  of  arfenic  taken  in  fo- 
lotion.  See  Suppl.  1.8.  8.  Art.  IV.  2  6.  9. 

3.  Some  branches  of  the  lymphatic  fyftem  become  inverted 
by  their  fympathy  with  other  branches,  which  are  only  ftimu- 
lated into  too  violent  abforption.  Thus,  when  the  ftomach  and 
duodenum  are  much  ftimulated  by  alcohol,  by  nitre,  or  by 
xvorms,  in  fome  perfons  the  urinary  lymphatics  have  their  mo- 
tion inverted,  and  pour  that  material  into  the  bladder,  which  is 
abforbed  from  the  inteftines.  Hence  the  drunken  diabetes 
is  produced ;  and  hence  chyle  is  feen  in  the  urine  in  worm  c^fes. 
When  on  the  contrary  fome  branches  of  the  abforbent  fyftems 
have  their  motions  inverted  in  confequence  of  the  previous  ex- 
hauftion  of  their  fenforial  power  by  any  violent  ftimulus,  other 

branches 


ART.  V.  2,  i.  4-  INVERTENTIA.  0*7 

branches  of  it  have  their  abforbent  power  greatly  iucreafed. 
Hence  continued  vomiting,  or  violent  cathartics,  produce  great 
abforption  from  the  cellular  membrane  in  cafes  of  dropfy  ;  and 
the  fluids  thus  abforbed  are  poured  into  the  flomach  and  intef- 
tines  by  the  inverted  motions  of  the  lacleals  and  lymphatics.  See 
Bed.  XXIX.  4  and  5. 

4.  The  quantity  of  the  dofe  of  an  emetic  is  not  of  fo  great 
confluence  as  of  other  medicines,  as  the  greateft  part  of  it  is 
rejected  with  the  firft  effort.  All  emetics  are  faid  to  act  with 
greater  certainty  when  given  in  a  morning,  if  an  opiate  had 
been  given  the  night  before.  For  the  fenforial  power  of  irrita- 
tion of  the  ftomach  had  thus  been  in  fome  meafure  previoufly 
e-xhaufted  by  the  ftimulus  of  the  opium,  which  thus  facilitates 
the  action  of  the  emetic ;  and  which,  when  the  dofe  of  opium 
has  been  large,  is  frequently  followed  on  the  next  day  by  fpon- 
taneous  ficknefs  and  vomitings,  as  after  violent  intoxication. 

Ipecacuanha  is  the  moil  certain  in  its  effect  from  five  grains 
to  thirty  ;  white  vitriol  is  the  mod  expeditious  in  its  effect, 
from  twenty  grains  to  thirty  diffolved  in  warm  water  ;  but  erne:- 
ic  tartar,  amimonium  tartarizatum,  from  one  grain  to  four  to 
fane  people,  and  from  thence  to  twenty  to  infane  patients,  will 
anfwer  mod  of  the  ufefui  purpofes  of  emetics ;  but  nothing 
equals  the  digitalis  purpurea  for  the  purpofe  of  abforbing  water 
from  the  cellular  membrane  in  the  anafarca  pulmonum,  or  hy- 
drops  pectoris.  See  Art.  II.  3  7. 

II.  Violent  cathartics,  i.  Where  violent  cathartics  are  re- 
quired, as  in  dropfies,  the  fquill  in  dried  powder  made  into 
fmall  pills  of  a  grain,  or  a  grain  and  a  half,  one  to  be  given  ev- 
ery hour  till  they  operate  brifkly,  is  very  efficacious  ;  or  half  a 
grain  of  emetic  tartar  diffolved  in  an  ounce  of  peppermint-water, 
and  given  every  hour,  till  it  operates.  Scammony,  and  other 
ftrong  purges,  are  liable  to  produce  hypercatharfis,  if  they  are 
not  nicely  prepared,  and  accurately  weighed,  and  are  thence 
dangerous  in  common  practice.  Gamboge  is  uncertain  m  its 
effects,  it  has  otherwife  the  good  property  of  being  taflelefs  ;  mu! 
on  that  account  fome  preparation  of  it  might  be  ufefui  for  chil- 
dren, by  which  its  dofe  could  be  afcertained,  and  its  effects  ren- 
dered more  uniform. 

2.  In  inflammations  of  the  bowels  with  conftipatiou,  calomel, 
given  in  a  dofe  from  ten  to  twenty  grains  after  due  venefection, 
is  mod  efficacious  ;  and  if  made  into  very  fmall  pills  is  riot  lia- 
ble to  be  rejected  by  Vomiting,  which  generally  attends  thofe 
cafes.  When  this  fails,  a  grain  of  aloes  every  hour  will  find  hs 
way,  if  the  bowel  is  not  deltroycd  ;  and  fometimes,  I  believe,  if 
it  be,  when  the  mortification  is  not  extenfive.  If  the  vomiting 

continues 


68  INVERTENTTA.  ART.  V.  2.  3.  i. 

continues  after  the  pain  ceafes,  and  efpecially  if  the  bowels  be- 
come tumid  with  air,  which  founds  on  being  (truck  with  the 
finger,  thefe  patients  feldom  recover.  Opiates  given  along 
with  the  cathartics  I  believe  to  be  frequently  injurious  in  inflam- 
mation of  the  bowels,  though  they  may  thus  be  given  with  ad- 
vantage in  the  faturnine  colic  ;  the  pain  and  conftipation  in 
which  difeafe  are  owing  to  torpor  or  inactivity,  and  not  to  too 
great  action.  See  Clafs  I.  2.  4.  8. 

III.  Violent  errhines  and  fialagogues.      i.  Turpeth  mineral 
an  the  quantity  of  one  grain  mixed  with  ten  grains  of  fugar  an- 
fwers  every   purpofe  to  be  expected  from  errhines.     Their  ope- 
ration is  by  inverting  the  motions  of  the  lymphatics  of  the  mem- 
brane, which  lines  the  noftrils,  and  the  caverns  of  the  forehead 
and  cheeks  ;  and  may  thence  poflibly  be  of  fervice  in  the  hydro- 
cephalus  internus. 

Some  other  violent  errhines,  as  the  powder  of  white  hellebore, 
or  Cayenne  pepper,  diluted  with  fome  lefs  acrid  powder,  are  faid 
to  cure  fome  cold  or  nervous  head-achs  ;  which  may  be  effe6l- 
ed  by  inflaming  the  noftrils,  and  thus  introducing  the  fenforial 
power  of  fenfation,  as  well  as  increafing  that  of  irritation  ;  and 
thus  to  produce  violent  action  of  the  membranes  of  the  noftrils, 
and  of  the  frontal  and  maxillary  fmufes,  which  may  by  aflbcia- 
tion  excite  into  action  the  torpid  membranes,  which  occafion 
the  head-ach.  They  may  be  ufed  on  the  fame  account  in 
amaurofis  and  in  deafnefs. 

2.  A  copious  falivation  without  any  increafe  of  heat  often  at- 
tends hyfteric  difeafes,  and  fevers  with  debility,  owing  to  an  in- 
verfionof  the  lymphatics  of  the  mouth,  fee  Clafs  I.  i.  2.  6.  The 
fame  occurs  in  the  naufea,  which  precedes  vomiting  ;  and  is  alfo 
excitable  by  difagreeable  taftes,  as  by  fquills,  or  by  naufeous 
fmelis,  or  by  naufeous  ideas.  Thefe  are  very  (imilar  to  the  oc~ 
cafional  difcharge  of  a  thin  fluid  from  the  noftrils  of  fome  peo- 
ple, which  recurs  at  certain  periods,  and  differs  from  defective 
abforption. 

IV.  Violent  diuretics,     i .  If  nitre  be  given  from  a  dram  to 
half  an  ounce  in   a   morning  at  repeated  draughts,  the  patient 
becomes  fickifh,  and  much  pale  water  is  thrown  into  the  bladder 
by  the  inverted  a£Uon  of  the  urinary  lymphatics.     Hence  the 
abforption  in  ulcers  isincreafed  and  the  cure  forwarded,  as  ob- 
ferved  by  Dr.  Rowley. 

2.  Cantharides  taken  inwardly  fo  ftimulate  the  neck  of  the 
bladder  as  to  increafe  the  difcharge  of  mucus,  which  appears  in 
the  urine  ;  but  I  once  faw  a  large  dofe  taken  by  miftake,  not  lefs 
than  half  an  ounce  or  an  ounce  of  the  tinfture,  by  which  I  fup- 
pofe  the  urinary  lymphatics  were  thrown  into  violent  inverted 

motions, 


ART.V.  2/4.  3.  INVERTENTIA.  fip 

motions,  for  the  patient  drank  repeated  draughts  of  fubtepid 
water  to  the  quantity  of  a  gallon  or  two  in  a  few  hours  ;  and 
during  the  greateft  part  of  that  time  he  was  not  I  believe  two 
entire  minutes  together  without  making  water.  A  little  blood 
was  feen  is  his  water  the  next  day,  and  a  forenefs  continued  a 
day  longer  without  any  other  inconvenience. 

3.  The  decocYion  of  foxglove  (hould  alfo  be  mentioned  here, 
as  great  effufions  of  urine  frequently  follow  its  exhibition.    Sec 
Art.  IV.  2.  3.  7.     And  an  infufion  or  tincture  of  tobacco  as 
recommended  by  Dr.  Fowler  of  York. 

4.  Alcohol,  and  opium,  if  taken  fo  as  to  induce  flight  intoxi- 
ication,  and  the  body   be  kept   cool,  and  much  diluting  liquids 
taken  along   with   them,  have  fimilar  effect  in  producing  for  ;i 
time  a  greater  flow  of  urine,  as  molt  intemperate  drinkers  muft 
occafionally  have  obferved.     This  circumftance  feems  to  have 
introduced  the  ufe  of  gin,  and  other  vinous  fpirits,  as  a  diuretic, 
unfortunately   in  the  gravel,  amongft  ignorant  people  ;  which 
difeafe  is  generally  produced  by  fermented  or  fpirituous  liquors, 
and  always  increafed  by  them.          .     , 

5.  Fear  and  anxiety  are  well  known  to  produce  a  great  fre- 
quency of  making  water.     A  perfon  who  believed  he  had  made. 
a  bad  purchafe  concerning  an  eftate,  told  me,  that  he  made  five 
or  fix  pints  of  water  during  a  fleeplefs  night,  which  fucceeded 
his  bargain  ;   and  it  is  ufual,   where  young  men  are  waiting  m 
an  anti-room  to  be  examined  for  college  preferment,  to  fee  the 
chamber-pot  often  wanted. 

V.  Cold  fweats  about  the  head,  neck,  and  arms,  frequently 

attend  thofe,  whofe  lungs  are  opprerTed,  as  in  fome  dropfies  and 

afthma.     A  cold  fweat  is  alfo  frequently  the  harbinger  of  death , 

Thefe  are  from  the  inverted  motions  of  the  cutaneous  lymphat  - 

'ic  branches  of  thofe  parts. 

III.  CATALOGUE  OF  INVERTENTRA. 

I.  Emetics,    ipecacuanha,  emetic  tartar,  antimonmm  tartan' - 

fatum,  fquill,  fcilla  maritima,  carduus  benediclus,  cni~ 
cus  acarna,  chamomile,  anthemis  nobilis,  white  vitriol, 
vitriolum  zinci,  foxglove,  digitalis  purpurea,  clyftera 
of  tobacco. 

II.  Violent  cathartics,  emetic  tartar,  fquill,  buckthorn,  rham 

mis  catharticus,  fcammonium,  convolvulus  fcamrno- 
nia,  gamboge,  elaterium,  colocynth,  cucumis  colocyti- 
this,  veratrum. 

III.  Violent  errhines  and  Calagogues,  turpeth  mineral,  hydr;: 


REVERTENTIA.  ART.  VI.  i.  i. 


gyrus  vitriolatus,afarum  europium,  euphorbium,  cap- 
ficum,  veratrum,  nauteous  fmells,  naufeous  ideas. 

IV.  Violent    diuretics,  nitre,  fquill,  feneka,  cantharides,    al- 

coliol,  foxglove,  tobacco,  anxiety. 

V.  Cold  fudorifics,  poiibns,  fear,  approaching  death. 


ART.  VI. 
REVERTENTIA. 

I.  THOSE  THINGS,  which  reftore  the  natural  order  of  the  in- 
verted irritative  motions,  are  termed  Revertemia. 

1.  As  muflc,  caftor,  afafoetida,  valerian,  eflcntial  oils. 

2.  Externally  the   vapour  of  burnt  feathers,  of  volatile  falts, 
or  oils,  blifters,  finapifms. 

Thefe  reclaim  the  inverted  motions  without  increafing  the 
heat  of  the  body  above  its  natural  (late,  if  given  in  their  proper 
dofes,  as  in  the  globus  hyftericus,  and  palpitation  of  the  heart, 

The  incitantia  revert  thefe  morbid  motions  more  certainly,  as 
opium  and  alcohol  ;  and  reftore  the  natural  heat  more  ;  but  if 
they  induce  any  degree  of  intoxication,  they  are  fucceded  by 
debility,  when  their  fiimulus  ceafes. 

II.  OBSERVATIONS  ON  THE  REVERTENTIA. 

I.  i.  The  hyfteric  difeafe  is  attended  with  inverted  motions 
feebly  exerted  of  the  cefophagus,  inteftinal  canal  and  lymphat- 
ics of  the  bladder.  Hence  the  borborigmi,  or  rumbling  of  the 
bowels,  owing  to  their  fluid  contents  defcending  as  the  air  be- 
neath afcends.  The  globus  hyftericus  confifts  in  the  retrograde 
motion  of  the  cefophagus,  and  the  great  flow  of  urine  from  that 
of  the  lymphatics  ipread  on  the  neck  of  the  bladder  ;  and  a  copi- 
ous falivation  fometimes  happens  to  thefe  patients  from  the  in- 
verfion  of  the  lymphatics  of  the  mouth  ;  and  palpitation  of  the 
heart  owing  to  weak  or  incipient  inverlion  of  its  motions  ;  and 
fyncope,  when  this  occurs  in  its  greateft  degree. 

Thefe  hyfteric  affeclions  are  not  neceflarily  attended  with 
pain ;  though  it  fometimes  happens,  that  pains,  which  originate 
from  quiefcence,  afflict  theie  patients,  as  the  hemicrania,  which 
has  erroneoufly  been  termed  the  clavus  hyftericus  ;  but  which  is 
owing  folely  to  the  inaction  of  the  membranes  of  that  part,like 
the  pains  attending  the  cold  fits  of  intermittents,  and  which  fre- 
quently returns  like  them  at  very  regular  periods  of  time. 

Many 


ART.  V.  2.  2.  i.         REVERTENTIA.  71 

Many  of  the  above  fymptoms  are  relieved  by  mufk,  caftor, 
the  foetid  gums,  valerian,  oleum  animale,  oil  of  amber,  which 
aft  in  the  ufual  dofe  without  heating  the  body.  The  pains, 
which  fometimes  attend  thefe  conftitutions,  are  relieved  by  the 
fecernentia,  as  eflential  oils  in  common  tooch-ach,  and  balfam  of 
Peru,  in  the  flatulent  cholic.  But  the  incitantia,  as  opium,  or 
vinous  fpirit,  reclaim  thefe  morbid  inverted  motions  with  more 
certainty  than  the  foetids  ;  and  remove  the  pains  which  attend 
thefe  conftitutions,  with  more  certainty  than  the  fecernentia  5 
but  if  given  in  large  dofes,  a  debility  and  return  of  the  hyfteric 
fymptoms  occur,  when  the  effect  of  the  opium  or  alcohol  ceafes. 
Opiates  and  fcetids  joined  feem  b<  ft  to  anfwer  the  purpofe  of 
alleviating  the  prefent  fymptoms  ;  and  the  forbentia,  by  ftimu- 
lating  the  lymphatics  and  lafteals  into  continued  adlion,  prevent 
a  relapfe  of  their  inverfion,  as  Peruvian  bark,  and  the  ruft  of 
iron.  See  Clafs  I  3.  i.  10. 

II.  Vomiting  confifts  in  the  inverted  order  of  the  motions 
of  the  ftomach  and  cefophagus  ;  and  is   alfo  attended  with  the 
inverted  motions  of  a  part  of  the  duodenum,  when  bile  is  eject- 
ed ;  and  of  the  lymphatics  of  the  ftomach  and  fauces,  when 
naufea  attends,  and  when  much  lymph  is  evacuated.     Perma- 
nent vomiting  is  for  a  time  relieved  by  the  incitantia,  as  opium 
or  alcohol ;  but  is  liable  to  return  when-  their  aclion  ceafes.     A 
blifter  on  the  back,  or  on  the  ftomach,  is  more  efficacious  for  re- 
ftraining  vomiting  by  their  ftimulating  into  adlion  the  external 
fkin,  and  by  fympathy  affecling  the  membranes  of  the  ftomach. 
In  fome  fevers  attended  with  inceflant  vomiting  Sydenham  ad- 
vifed  the  patient  to  put  his  head  under  the  bed  clothes,  till  a 
fweat  appeared  on  the  fkin,  as  explained  in  Clafs  IV.  i.  1,3. 

In  chronical  vomiting  I  have  obferved  crude  mercury  of  good 
effect  in  the  dofe  of  half  an  ounce  twice  a  day.  The  vomitings, 
or  vain  efforts  to  vomit,  which  fometimes  attend  hyfteric  or  ep- 
ileptic patients,  are  frequently  inftantly  relieved  for  a  time  by 
applying  flour  of  multard-feed  and  water  to  the  fmall  of  the 
leg  ;  and  removing  it,  as  foon  as  the  pain  becomes  considerable. 
If  Gnapifms  lie  on  too  long,  efpecially  in  paralytic  cafes,  they  are 
liable  to  produce  troublefome  ulcers.  A  plafter  or  cataplafm, 
with  opium  and  camphor  on  the  region  of  the  ftomach,  will 
fometimes  revert  its  retrograde  motions. 

III.  Violent  catharfis,  as  in  diarrhoea  or  dyfentery,  is  attend- 
ed with  inverted  motions  of  the  lymphatics  of  the  inteilines,  and 
is  generally  owing  to  fome  ftimulating  material.     This  is  coun- 
teracted by  plenty  of  mucilaginous  liquids,  as  folutions  of  gum 
arabic,  or  fmall  chicken  broth,  to  wafh  away  or  dilute  the  ftim- 
ulating material,  which  caufes  the  difeafe.     And  then  by  the  ufe 

VOL.  I.  W  w  w  of 


72  REVERTENTIA.  ART.  VI.  a.  4.  r, 

of  the  inteftinal  forbentia,  Art.  IV.  2  5.  as  rhubarb,  deco&ion 
of  logwood,  calcined  hartihorn,  Armenian  bole  ;  and  laftly,  by 
the  incitantia,  as  opium. 

IV.  The  diabcetes  confifts  in   the   inverted   motions  of  the 
urinary  lymphatics,  which  is  generally  I  fuppofe  owing  to  the 
too  great  attion  of  fome  other  branch  of  the  abforbent  fyftem. 
The  urinary  branch  fhould  be  ftimulated  by  cantharides,  turpen- 
tine, refin,  (which  when  taken  in  larger  dofes  may  poffibly  excite 
it  into  inverted  action),  by  the  forbentia  and  opium.     The  intef- 
tinal lymphatics  fhould   be   rendered  lefs  active   by  torpentia, 
as  calcareous  earth,   earth  of  alum ;  and   thofe  of  the  fldn  by 
oil  externally  applied  over  the  whole  body  ;  and  by  the  warm- 
bath,  which  fhould  be  of  ninety-iix  or  ninety-eight  degrees  of 
heat,  and  the  patient  fhould  fit  in  it  every  day  for  half  an  hour. 

V.  Inverted  motions  of  the  inreftinal  canal  with  all  the  lymph- 
atics, which  open  into  it,   conftitute  the  ileus,  or  iliac  paflion  \ 
in  which  difeafe  it  (bmetimes  happens,  that  clyfters  are  returned 
by  the  mouth.     After  venefedHon  from  ten  grains  to  twenty  of 
calomel  made  into  very  fmall  pills  ;  if  thefe  be  rejected,  a  grain 
of  aloe  every  hour  ;  a  blifter,  crude  mercury  j  warm-bath ;   if  a 
clyfter  of  iced  water  ? 

Many  other  inverted  motions  of  different  parts  of  the  fyftem 
are  defcribed  in  Clafs  I.  3.  and  which  are  to  be  treated  in  a  man- 
ner fimilar  to  thofe  above  defcribed.  It  mud  be  noted  that 
the  medicines  mentioned  under  number  one  in  the  catalogue  of 
revertentia  are  the  true  articles  belonging  to  this  clafs  of  medi- 
cines. Thofe  enumerated  in  the  other  four  divifions  are  chiefly 
fuch  things  as  tend  to  remove  the  ftimulating  caufes,  which 
have  induced  the  inverfion  of  the  motions  of  the  part,  as  acrimo- 
nious contents,  or  inflammation,  of  the  bowels  in  diarrhoea,  dia- 
betes or  in  ileus.  But  it  is  probable  after  thefe  remote  caufes 
are  deflroyed,  that  the  fetid  gums,  mufk,  caftor,  and  balfams, 
might  be  given  with  advantage  in  all  thefe  cafes. 

III.  CATALOGUE  OF  REVERTENTIA. 

I.  Inverted  motions,  which  attend  the  hyfteric  difeafe,  are  re- 
claimed, i.  By  mufk:,  caftor.  2.  By  afafcetida,  galba- 
num,  fagapenum,  amrnoniacum,  valerian.  3.  Eflential 
oils  of  cinnamon,  nutmeg,  cloves,  infufion  of  penny-roy- 
al, mentha,  pulegium,  peppermint,  mentha  piperita,  e- 
ther,  camphor,  4,  Spirit  of  hartfhorn,  oleum  animale, 
fponge  burnt  to  charcoal,  black  fnufFs  of  candles,  which 
confift  principally  of  animal  charcoal,  wood-foot,  oil  of 
amber.  5,  The  incitantia,  as  opium,  alcohol,  vinegar.  6. 

Externally 


ART.  VII.  i.i.  TORPENTI A.  7  3 

Externally  the  fmoke  of  burnt  feathers,  oil  of  amber,  vol- 
atile fait  applied  to  the  noftrils,  blifters,  finapifms. 

II.  Inverted  motions  of  the  ftomach  are  reclaimed  by  opium, 

alcohol,  bliflers,  crude  mercury,  Gnapifms,  camphor  and 
opium,  externally,  clyfters  with  afafoetida. 

III.  Inverted  motions  of  the  inteftinal  lymphatics  are  reclaim- 
ed by  mucilaginous  diluents,  and  by  inteftinal   forben- 
tia,  as  rhubarb,  logwood,  calcined  hartihorn,  Armenian 
bole  ;   and  laftly  by  incitantia,  as  opium. 

IV.  Inverted  motions  of  the  urinary  lymphatics  are  reclaim- 
ed by  cantharides,  turpentine,  refin,  the  forbentja,  and 
opium,  with  calcareous  earth  of  alum,  by  oil  externally, 
warm-bath. 

V.  Inverted  motions  of  the  inteftinal  canal  are  reclaimed  by 

calomel,  aloe,  crude  mercury,  bliiters,  warm-bath,  clyf- 
ters with  afafoetida,  clyfters  of  iced  water  ?  or  of  fpring 
water  further  cooled  by  fait  diflblved  in  water  contained 
in  an  exteriour  veflel  ?  Where  there  exifts  an  introfuf- 
ception  of  the  bowel  in  children,  could  the  patient  be 
held  up  for  a  time  by  the  feet  with  his  head  downwards, 
or  be  laid  with  his  body  on  an  inclined  plane  with  his 
head  downward,  and  crude  mercury  be  injected  as  a 
clyfter  to  the  quantity  of  two  or  three  pounds  ? 


ART.  VII. 
TORPENTIA. 

I.  THOSE  things,  which  diminifli  the  exertion  of  the  irritative 
motions,  are  termed  torpentia. 

1.  As  mucus,    mucilage,   water,   bland  oils,  and    whatever 
pofTeffes  lefs  ftimulusthan  our  ufual  food.     Diminution  of  heat, 
light,  found,  oxygene,  and  of  all  other  ftimuli ;  venefedion,  nau- 
fea  and  anxiety. 

2.  Thofe  things  which  chemically  deftroy  acrimony,  as  calca- 
reous earth,  foap,  tin,  alkalies,  in  cardialgia  ;  or  which  prevent 
chemical  acrimony,  as  acid  of    vitriol  in  cardialgia,  which  pre- 
vents the  fermentation  of  the  aliment  in  the  ftomach,   and  its 
confequent  acidity.     Secondly,   which  deftroy  worms,   as  calo- 
mel, iron  filings  or  ruft  of  iron,  in  the  round  worms  ;  or  amal- 
gama  of  quickfilver  and  tin,  or  tin  in  very  large  dofes,    in  the 
tape-worms.    Will  either  in  clyfters  deftroy  afcarides  ?  Thirdly, 
by  chemically  deftroying  extraneous   bodies,   as  cauftic   alkali, 
lime,  mild  alkali  in  the  (lone.     Fourthly,  thofe  things  which  lu- 
bricate 


74  TORPENTIA.  ART.  VII.  2.  i.  iv 

bricate  the  veflels  along  which  extraneous  bodies  Hide,  as  oil  in 
the  ftone  in  the  urethra,  and  to  expedite  the  expectoration  of 
hardened  mucus  ;  or  which  leflen  the  friftion  of  the  contents 
in  the  intelHnal  canal  in  dyfentery  or  aphtha,  as  calcined  hartf- 
horn,  clay,  Armenian  bole,  chalk,  bone-afhes.  Fifthly,  fuch 
things  as  foften  or  extend  the  cuticle  over  tumors,  or  phleg- 
mons, as  warm  water,  poultices,  fomentations,  or  by  confining 
the  perfpirable  matter  on  the  part  by  cabbage-leaves,  oil,  fat, 
beeVwax,  plaflers,  oiled  filk,  externally  applied. 

Thefe  decreafe  the  natural  heat  and  remove  pains  occafioned 
by  excefs  of  irritative  motions. 

II.  OBSERVATIONS  ON  THE  TORPENTIA. 

I.  As  the  torpentia  confift  of  fuch  materials  as  are  lefs  ftim- 
ulating  than  our  ufual  diet,  it  is  evident,  that  where  this  clafs  of 
medicines  is  ufed,  fome  regard  mud  be  had  to  the  ufual  manner 
of  living  of  the  patient  both  in  reipecr,  to  quantity  and  quality. 
Hence  wounds  in  thofe,  who  have  been  accuftomed  to  the  ufe 
of  much  wine,  are  very  liable  to  mortify,  unlefs  the  ufual  pota- 
tion of  wine  be  allowed  the  patient      And  in  thefe  habits  I  have 
feen  a  delirium  in  a  fever  cured  almoft  immediately  by  wine  ; 
which  was  occafioned  by  the  too  mild  regimen  directed  by  the 
attendants.     On  the  contrary   in  great   inflammation,   the  fub-* 
duclion  of  food,  and  of  fpirituous  drink,  contributes  much  to  the 
cure  of  the  difeafe.     As  by  thefe  means  both  the  ftimulus  from 
diftention  of  the  veflels,    as  well  as  that  from  the  acrimony  of 
the  fluids,  is  decreaied ;  but  in  both  thefe  refpe&s  the  previous 
habits  of  diet  of  the  patients  muft  be  attended  to.     Thus  if  tea 
be  made  ftronger,  than  the  patient  has  ufually  drunk  it,    it  be- 
longs to  the  article  forbentia  •,  if  weaker,  it  belongs  to  the  tor- 
pentia. 

II.  i.  Water  in  a  quantity  greater  than  ufual  diminifhes  the 
action  of  the  fyftem  not  only  by  diluting  our  fluids,  and  thence 
leiTening  their  ftimulus,  but  by  lubricating  the  folids  ;  for  not 
only  parts  of  our  folids  have  their  fliding  over  each  other  facili- 
tate by  the  interpofition  of  the  aqueous  particles;  but  the  particles 
of  mucaginous  or  faccharine  folutions  flide  eafier  over  each  oth- 
er by  being  mixed  with  a  greater  portion  of   water,  and  thence 
ftimulate  the  veflels  lefs. 

At  the  fame  time  it  muft  be  obferved,  that  the  particles  of 
water  themfelves,  and  of  animal  gluten  diilblved  in  water,  as 
the  glue  ufed  by  carpenters,  flide  eafier  over  each  other  by  an 
additional  quantity  of  the  fluid  matter  of  heat. 

Thefe  two  fluids  of  heat  and  of  water  may  be  efteemed  the 

upiverfal 


ART.  VII.  i.  3.  i.  TORPENTIA.  7$ 

univerfal  folvents  or  lubricants  in  refpecl  to  animal  bodies,  and 
thus  facilitate  the  circulation,  and  the  fecretion  of  the  various 
glands.  At  the  fame  time  it  is  poflibly,  that  thefe  two  fluids 
may  occafional  afTume  an  aerial  form,  as  in  the  cavity  of  the 
cheft,  and  by  compreffing  the  lungs  may  cauie  one  kind  of 
afthma,  which  is  relieved  by  breathing  colder  air.  An  increaf- 
ed  quantity  of  heat  by  adding  ftimulus  to  every  part  of  the  fyf- 
tem  belongs  to  the  article  Incitantia. 

III.  i.  The  application  of  cold  to  the  flcin,  which  is  only 
another  expreflion  for  the  diminution  of  the  degree  of  heat  we 
are  ai:cu(tomed  to,  benumbs  the  cutaneous  abforbents  into  inac- 
tion ;  and  by  fympathy  the  urinary  ai^d  inteftinal  abforbents  be- 
come alfo  quiefce nt-  The  fecerning  vefTels  continuing  their  ac- 
tion fomewhat  longer,  from  the  warmth  of  the  blood.  Hence 
the  ufuai  fecretions  are  poured  into  the  bladder  and  inteftines, 
and  no  abforption  is  retaken  from  them.  Hence  fprinkling  the 
fkin  with  cold  water  increafes  the  quantity  of  urine,  which  is 
j  and  of  ftool,  which  is  fluid  9  thefe  have  erroneoufly  been 
aicribed  to  increafed  fecretion,  or  to  obftrudted  perfpiration. 

The  thin  difcharge  from  the  noflrils  of  fome  people  in  cold 
weather  is  owing  to  the  torpid  ftate  of  the  abibrbent  veflels  of 
the  membrana  fchneidenana,  which  as  above  are  benumbed 
fooner  than  thofe,  which  perform  the  fecretion  of  the  mucus. 

The  quick  anhelation,  and  palpitation  of  the  heart,  of  thofe, 
who  are  immerfed  in  cold  water,  depends  on  the  quiefcence  of 
the  external  abforbent  veflels  and  capillaries.  Hence  the  cuta- 
neous circulation  is  diminifhed,  and  by  aflbciation  an  almofl 
univerfal  torpor  of  the  fyitem  is  induced  ;  thence  the  heart  be- 
comes incapable  to  puih  forwards  its  blood  through  all  the  inac- 
tive capillaries  and  glands  ;  and  as  the  terminating  vefleisof  the 
pulmonary  artery  fuffer  a  (imilar  inaction  by  aflociation,  the 
blood  is  with  difficulty  pumed  through  the  lungs. 

Some  have  imagined,  that  a  fpafmodic  conftriclion  of  the 
fmaJler  veflels  took  place,  and  have  thus  accounted  for  their  re- 
Citance  to  the  force  of  the  heart.  But  there  feems  no  neceflity 
to  introduce  this  imaginary  fpafm  ;  fmce  thofe,  who  are  con. 
verfant  in  injecting  bodies,  find  it  neceflary  firft  to  put  them, 
into  warm  water  to  take  away  the  (lifFnefs  of  the  cold  dead  vef- 
fels  •,  which  become  inflexible  like  the  other  mufcles  of  dead 
animals,  and  prevent  the  injected  fluid  from  pafling. 

Before  the  improved  knowledge  of  chemiilry,  and  of  natural 
philofophy,  and  of  the  laws  of  organic  life,  fome  writers  have 
fpoken  of  cold  as  a  ftimulus  to  the  fyftern,  inftead  of  fpeaking 
of  ir  as  a  diminution  of  the  ftimulus  of  heat.  But  the  immedi- 
ate confequence  of  ftimulus  is  the  exertion  of  the  ftimulated 

fibres  ; 


?6  TORPENTIA.          ART.  VII.  2.  3.  *. 

fibres  ;  now  an  incrcafed  application  of  heat  is  followed  by  an 
increased  action  of  the  fibres  expofed  to  it  ;  but  an  increafed 
application  of  cold  is  followed  by  a  decreafed  action  of  the  fibres 
expofed  to  it;  as  appears  by  the  rednefs  of  our  hands  when 
warmed  by  the  fire*  and  the  palenefs  of  them,  when  they  have 
been  a  while  covered  with  fnow. 

A  painful  fenfation  fucceeds  the  defect  as  well  as  the  excefs 
of  the  ftimulus  of  heat,  as  mentioned  in  Vol.  L  Seel  IV.  5. 
and  the  voluntary  exertions  of  the  fubcutaneous  mufcles  called 
(huddering,  are  excited  to  relieve  the  pain  occafioned  by  the  tor- 
por of  the  fibres  expofed  to  cold  ;  and  thofe  of  the  mufcles 
fubfervient  to  refpiration  are  voluntarily  excited  in  fcreaming  to 
relieve  the  pain  occafioned  by  heat,  which  may  have  occafioned 
the  error  above  mentioned. 

Others  have  fpoken  of  a  fedative  quality  of  cold,  which  is  cer- 
tainly an  unphilofophical  expreflion  ;  as  a  fedative  power,  if  it 
lias  any  diftinct  meaning,  mould  exprefs  a  power  of  diminifhing 
any  unnatural  or  exceflive  motions  of  the  fyftem  ;  but  the  ap- 
plication of  cold  diminimes  the  activity  of  the  fibres  in  general, 
which  may  previoufly  be  lefs  than  natural,  as  well  as  greater. 

All  the  fame  fymptoms  occur  in  the  cold  fits  of  intermit- 
tents  ;  in  thefe  the  coldnefs  and  palenefs  of  the  ikin  with  thirit 
evince  the  diminution  of  cutaneous  ablbrption  ;  and  the  clrynefs 
of  ulcers,  and  fmall  fecretion  of  urine,  evince  the  torpor  of  the 
fecerning  fyftem  ;  and  the  anhelation,  and  coldnefs  of  the 
breath,  (hew  the  terminations  of  the  pulmonary  artery  to  be 
likewife  affected  with  torpor., 

After  thefe  veflels  of  the  whole  furf  ace  of  the  body  both  ab- 
forbent  and  fecretory  have  been  for  a  time  torpid  by  the  appli- 
cation of  cold  water  -,  and  all  the  internal  fecerning  and  aforb- 
ent  ones  have  been  made  torpid  from  their  aflbciation  with  the 
external  ;  as  foon  as  their  ufua!  (limulus  of  warmth  is  renewed, 
they  are  thrown  into  more  than  their  ufual  energy  of  action  ; 
as  the  hands  become  hot  and  painful  on  approaching  the  fire 
after  having  been  immerfed  fome  time  in  fnow.  Hence  the 
face  becomes  of  a  red  colour  in  a  cold  day  on  turning  from  the 
wind,  and  the  infenfible  perfpiration  increafed  by  repeatedly  go- 
ing into  frofty  air,  but  not  continuing  in  it  too  long  at  a  time. 

2.  When  by  the  too  great  warmth  of  a  room  or  of  clothes 
the  fecretion of  perfpirable  matter  is  much  increafed, the  ftrength 
of  the  patient  is  much  exhaufted  by  this  unnecefiary  exertion  of 
the  capillary  fy item,  and  thence  of  the  whole  fecerning  and  ar- 
terial fyilem  by  aflbciation.  The  diminution  of  external  heat 
immediately  induces  a  torpor  or  quiefcence  of  thefe  unneceflary 
exertions,  and  the  patient  ^inftantly  feels  himfelf  ftrengthenec^ 

and 


ART.  VII.  2.  3.  2.          TORPENTIA.  77 

and  exhilarated  ;  the  animal  power,  which  was  thus  waded  in 
vain,  being  now  applied  to  more  ufeful  purpofes.  Thus  when 
the  limbs  on  one  fide  are  difabled  by  a  ftroke  of  the  pally,  thofe 
of  the  other  fide  are  perpetually  in  motion.  And  hence  all 
people  bear  riding  and  other  exercifes  beft  in  cold  weather. 

Patients  in  fevers,  where  the  (kin  is  hot,  are  immediately 
flrengthened  by  cold  air ;  which  is  therefore  of  great  ufe  in  fe- 
vers attended  with  debility  and  heat  ;  but  may  perhaps  be  of 
temporary  diflervice,  if  too  haftily  applied  in  fome  fituations  of 
fevers  attended  with  internal  topical  inflammation,  as  in  peri- 
pneumony  or  pleurify,  where  the  arterial  fhrength  is  too  great  al- 
ready, and  the  increafed  action  of  the  external  capillaries  being 
deftroyed  by  the  cold,  the  action  of  the  internal  inflamed  part 
may  be  fuddenly  increafed,  unlefs  venefection  and  other  evacu- 
ations are  applied  at  the  fame  time.  Yet  in  mod  caies  the  ap- 
plication of  cold  is  neverthelefs  falutary,  as  by  decreafing  the 
heat  of  the  particles  of  blood  in  the  cutaneous  veffels,  the  ftim- 
ulus  of  them,  and  the  diitention  of  the  veflels  becomes  confider- 
ably  lefTened.  In  external  inflammations,  as  the  fmall-pox,  and 
perhaps  the  gout  and  rhcumatifm,  the  application  of  cold  air 
muit  be  of  great  fervice  by  decreafing  the  action  of  the  inflamed 
fkin,  though  the  contrary  is  too  frequently  the  practice  in  thofe 
difeafes.  It  muft  be  obferved,  that  for  all  thefe  purpofes  the  ap- 
plication of  it  fhould  be  continued  a  long  time,  other  wife  an  in- 
creafed exertion  follows  the  temporary  torpor,  before  the  difeafe 
is  deftroyed. 

The  topical  application  of  cold  to  relieve  inflammatory  pains, 
or  to  deftroy  the  too  great  action  of  the  vefTels,  may  be  ufed 
with  great  advantage.  In  local  inflammations,  as  in  the  pleuri- 
fy, or  ophthalmia,  or  in  local  pains  from  the  ftimulus  of  an  ex- 
traneous body,  as  in  gravel  descending  along  the  ureter,  the  ap- 
plication of  cold  on  or  near  the  affected  part  may  be  ufed  with 
falutary  effect,  as  by  prefling  on  the  part  a  bladder  full  of  cold 
water  with  fait  difiblving  in  it  ;  or  by  the  evaporation  of  ether 
on  it  ;  which  may  render  the  vefTels  torpid  or  inactive.  But  the 
application  of  cold  to  the  whole  fkin  might  increafe  the  action 
of  the  inflamed  vefTels  by  diminifhing  that  of  the  fkin  and  lungs, 
and  thus  accumulating  a  greater  quantity  of  fenforial  power  \ 
and  this  efpecially  if  it  was  applied  previous  to  evacuations  by 
the  lancet  or  by  cathartics. 

I  am  informed  that  an  ingenious  and  eminent  furgeon  in 
Shropfhire,  when  he  was  himfelf  afreet ed  with  gravel  in  the  ure- 
ter, attended  with  exceflive  and  continued  pain,  found  inftanta- 
neous  relief  frequently  in  a  day  by  applying  on  the  painful  part 
a  bag  of  fnow  or  pounded  ice,  and  fuffering  it  to  diflblve.  And 
in  the  Memoirs  of  the  Medical  Society  of  London,  Vol.  V.  Mr. 

Parkinfon 


78  TORPENTIA.  ART.  VII.  2. 3. 4, 

Parkinibii  of  Leieefter  applies  cold  ingenioufly  to  burns,  and  to 
inflammations  of  the  eyes  by  covering  the  part  with  a  bladder 
of  the  greatefl  tenuity,  which  is  kept  perpetually  moiitened  for 
many  hours,  (perhaps  24  or  36)  by  alcohol  or  highly  rectified 
fpirit  of  wine.  In  opththalrnia  the  eyelids  were  thus  covered 
with  thin  bladder,  and  rectified  fpirit  of  wine  was  applied  by 
means  of  a  fponge  to  the  bladder  for  iome  hours ;  which  fucceed- 
ed,  after  faterine  lotions  had  been  ufed  in  vain,  and  deftroyed 
the  inflammation  as  foon  as  two  ounces  of  alcohol  had  been 
confumed.  Perhaps  ether  by  its  quicker  evaporation  might  be 
more  fpeedily  affect ual  ?  or  fnow  or  ice  thawed  more  haftily 
by  the  addition  of  acid  of  nitre  ? 

3.  After  immerfion  in  cold  water  or  in  cold  air  the  whole 
fyftem  becomes  more  excitable  by  the  natural  degree  of  ftimu- 
3 us,  as  appears  from  the  fubfequent  glow  on  the  Ikin  of  people 
otherwife  pale  :  and  even  by  a  degree  of  ilimulus  lefs  than  natur- 
al, as  appears  by  their  becoming  warm  in  a  (hort  time  during 
their  continuance  in  a  bath,  of  about  80  degrees  of  heat,  as  in 
Buxton  bath.     See  Sett.  XII.  2.  i.  XXXII  3  3. 

This  increafed  exertion  happens  to  the  -abforbent  vefTels  more 
particularly,  as  they  are  fir  ft  and  moft  affected  by  thefe  tempo- 
rary diminutions  of  heat ;  and  hence,  like  the  medicines,  which 
promote  abforption,  the  cold  bath  contributes  to  ftrengthen  the 
conftitution,  that  is  to  increafe  its  irritability  ;  for  the  difeafes, 
attended  with  weaknefs,  as  nervous  fevers  and  hyfteric  difeafes, 
are  (hewn  in  Sect  XXXII,  2.  i.  to  proceed  from  a  want  of  ir- 
ritability, not  from  an  excefs  of  it.  Hence  the  digellion  is 
greater  in  frofty  weather,  and  the  quantity  of  perfpiration.  For 
thefe  purpofes  the  application  of  cold  mull  not  be  continued  too 
long.  For  in  riding  a  journey  in  cold  weather,  when  the  feet 
are  long  kept  too  cold,  the  digeftion  is  impaired,  and  cardialgia 
produced. 

4.  If  the  diminution  of  external  heat  be  too  great,  produced 
too  haflily,  or  continued  too  long,   the  torpor  of  the  fyftem  ei- 
ther becomes   fo  great,  that  the  animal  ceafes  to  live  -,  or   fo 
great  an  energy  of  motion  or  orgafm  of  the  veilels  fucceeds,  as 
to  produce  fever  or  inflammation.     This   moft  frequently  hap- 
pens after  the   body  has  been  temporarily  heated  by  exercife, 
warm  rooms,  anger,  or  intemperance.     Hence  colds  are  produ- 
ced in  the  external  air  by   reftmg  after  exercife,  or  by  drinking, 
eold  water      See  Ciafs  I   2.  2.  i. 

Frequent  cold  immerfions  harden  or  invigorate  the  conftitu- 
tion, which  they  effect  by  habituating  the  body  to  bear  a  dimi- 
mution  of  heat  on  its  furface  without  being  thrown  into  iuch 
extenfive  torpor  or  quiefcence  by  the  confent  of  the  vefTels  oi: 
fhe  fkin  with  the  pulmonary  and  glandular  fyftem  •,  as  thofe 

experience, 


ART.  VII.  2. 4. 5.  TORPENTIA.  70 

experience,  who  frequently  ufe  the  cold  bath.  At  fir  ft  they 
have  great  anhelation  and  palpitation  of  heart  at  their  ingrefs 
into  cold  water  ;  but  by  the  habit  of  a  few  weeks  they  are  able 
to  bear  this  diminution  of  heat  with  little  or  no  inconvenience  ; 
for  the  power  of  volition  has  fome  influence  over  the  mufcles 
fubfervient  to  refpiration,  and  by  its  counter  efforts  gradually 
prevents  the  quick  breathing,  and  diminifhes  the  aflbciations  of 
the  pulmonary  vefiels  with  the  cutaneous  ones.  And  thus  though 
the  fame  quantity  of  heat  is  fubdutted  from  the  1km,  yet  the 
orpor  of  the  pulmonary  veflels  and  internal  g'ands  does  not 
follow.  Hence  during  cold  immerfion  lefs  fenforial  power  is  ac- 
cumulated, and,  in  confequence,  lefs  exertion  of  it  fucceeds  on 
emerging  from  the  bath.  Whence  fuch  people  are  efteemed 
hardy,  and  bear  the  common  variations  of  atmofpheric  temper- 
ature without  inconvenience.  See  Sedt.  XXXII.  3.  2. 

IV.  Venefeclion  has  a  juft  a   title  to  be   claifed  amongft  the 
torpen'ia  in  cafe^  of  ff  v:r  with  arterial  ftreruth,  known  by  the 
fulnefs  and  harclnefs  of  the   puife.     In  thefe  cafes  the  heat  be- 
comes lefs   by  its  ufe,  and   all  exuheranr  fecretions,  as  of  bile  or 
iweat,  are  diminiihed,  and  room  is  m^d^  in  the  blood-veflels  for 
the   abforption  of  mild    fluids  ;     and  hence   the  abforption  aJib 
of  new  veflels,  or  extravafated   fluids,  the   produce  of  inflam- 
mation, is  promoted.     Hence   venefe&ion  is  properly   clatfed 
amongft  the  forbentia,  as  like  other  evacuations  it  promotes  gen- 
eral abforption,  reftrains  haemorrhages,  and  cures  thofe  pains, 
which  originate  from  the  too  great  aftion  of  the  fecerning  vef- 
fels,  or  from  the  torpor  of  the  abforbents.     I  have  more  than 
once  been  witnefs  to  the  fudden  removal  of  nervous    head-achs 
by  veneieftion,  though  the  patient  was  already  exhaulted,   pale, 
and  feeble  -,    and  to   its  great  ufe  in  convulfions  and  madnefs, 
weather  the  patient  was  itrong  or  weak  ;  which  difeafes  are  the 
conlequence  of  nervous  pains  ,  and  to  its  (lopping  long  debili- 
tating haemorrhages  from    the  uterus,  when   other   means  had 
been  in  vain  eflayed.     In  inflammatory  pains,  and  inflammato- 
ry haemorrhages,  every  one  juftly  applies  to  it,  as  the  certain  and 
only  cure. 

V.  When  the   circulation  is  carried  on  too  violently,  as  in 
inflammarory  fevers,  thofe  medicines,  which  invert  the  motions 
of  fome  parts  of  the  fyftem,  retard  the  motions  of  fome  other 
parts,  which  are  aflbciated    with   them.     Hence   fmall  doies  of 
emetic  tartar,  and  ipecacuanha,  and  large  dofes  of  nitre,  by  pro- 
ducing naufea  debilitate  and  leflen  the  energy  of  the  circulation, 
and  are  thence  ufeful  in  inflammatory  difeafes.     It  mud  be  add- 
ed that  if  nitre  be  fwallowed   in  powder,  or  foon  after  it  is  dif- 
folved,  it  contributes  to  leilen  the  circulation  by  the  cold  it  gen- 
erates, like  ice-water,  or  the  external  application  of  cold  air. 

VOL.  I.  Xxx  VI.  The 


TORPENTIA 


ART.  VII.  2.  6. 


VI.  The  refpiration  of  air,  mixed  with  a  greater  proportion 
of  azote  than  is  found  in  the  common  atmofphere,  or  of  air  mix- 
ed with  hydrogen,  or  with  carbonic  acid  gas,  fo  that  the  quanti- 
ty of  oxygen  might  be  lefs  than  ufual,  would  probably  aft  in 
cafes  of  inflammation  with  great  advantage.  In  confumptions 
this  might  be  moil  conviently  and  effectually  applied,  if  a 
phthifical  patient  could  refide  day  and  night  in  a  porter  or  ale 
brewery,  where  great  quantities  of  thofe  liquors  were  perpetu- 
ally fermenting  in  vats  or  open  barrels  ;  or  infome  great  manu- 
fuc\ory  of  wines  from  raifins  or  from  fugar. 

Externally  the  application  of  carbonic  acid  gas  to  cancers 
and  other  ulcers  inftead  of  atmofpheric  air  may  prevent  their 
enlargement,  by  preventing  the  union  of  oxygen  with  the  mat- 
ter, and  thus  producing  a  new  contagious  animal  acid. 

HI.  CATALOGUE  OF  TORPENTIA. 

1.  Venefeftion.     Arteriotomy. 

2.  Cold  water,  cold  air,  refpiration  of  air  with  lefs  oxygen. 

3.  Vegetable  mucilages. 

a.  Seeds. — Barley,  oats,  rice,  young  peas,  flax,   cucumber, 
melon,  &c. 

b.  Gums. — Arabic,   tragacanth,  Senegal,  of   cherry-trees. 

c.  Roots  — Turnip,  potatoe,  althea,  orchis,  fnow-drop. 

d.  Herbs. — Spinach,  brocoli,  mercury. 

4.  Vegetable  acids,   lemon,  orange,  currants,   goofeberries, 

apples,  grape,  &c. 

5.  Animal  mucus,  hartfliorn  jelly,  veal  broth,  chicken  water, 

oil  ?  fat  ?  cream  ? 

6.  Mineral  acids,  of  vitriol,  nitre,  fea-falt. 

7.  Silence,  darknefs. 

.  Invertentia  in  fmall  dofes,  nitre,  emetic  tartar,  ipecacuanha 
given  fo  as  to  induce  naufea. 
p.  Antacids. — Soap,  tin,  alkalies,  earths. 

10.  Medicines  preventive  of  fermentation,  acid  of  vitriol. 

1 1.  Anthelmintics.—  Indian  pink,  tin,  iron,cowhage,  amalga- 
ma,  fmoke  of  tobacco. 

12.  Lithontriptics,  lixiv.  faponarium,  aqua  calcis,  taxable  air, 

13.  Externally,  warm  bath,  and  poultices, oil, fat,  wax,  platters, 

oiled  filk,  carbonic  acid  gas  on  cancers,  and  other  ulcers. 


END   OF    THIRD    PART. 


INDEX 


TO    THE 

SECTIONS  OF  PART  FIRST. 


LBORTION  from  fear,  xxxix.  6,  5. 
Abforption  of  folids, xxxiii.  3,  l,xxxvii. 
of  fluids  in  anafarca,  xxxv. 

1,  3. 

in    warm   bath,  xxix.   4,5. 
Abforbent  veflels,  xxii.  2,  xxix.  1. 

regurgitate     their       fluids, 

xxix.  2. 

their  valves,  xxix.  2. 
communicate     with     vena 
portarum,  xxvii.  2. 
Accumulation   of  fenforial  power,  iv. 

2,  xii.  5,  2. 
Activity  of  fyftem  too   great,  cure  of, 

xii.  6. 

too  fmall,  cure  of,  xx.  7. 
Age,  old,  xii.  3, 1,  xxxvii.  4. 
Ague-fit,  xii.    7,  l,xxxii.  3,  4, xxxii.  9. 
how    cured   by  bark,  xii.  3,  4. 
periods,  how   occauoned,  xii. 
2,  3,   xxxii.    3,  4,  xvii.  3,  6. 
Ague  cakes,  xxxii.  7,  xxxii.  9. 
Air,  fenfe  of  frefli,  xiv.  8. 
injures  ulcers,  xxviii.  2. 
injected  into  veins,  xxxii.  5. 
Air-cells  of  the  lungs,  xxviii.  2. 
Alcohol  deleterious,  xxx.  3. 
Alliterations,  why  agreeable,  xxii.  2. 
Aloes  in  leflened  dofes,  xii.  3, 1. 
American  natives  indolent,  xxxi.  2. 

narrow  fhouldered, 

xxxi.  1. 

Analogy  intuitive,  xvii.  3,  7. 
Animals  lefs  liable  to  madnefs,  xxxiii.  1. 
lefs  liable  to  contagion, xxxiii.  1. 
how  to  teach,  xxii.  3,  2. 
their  firmlarity   to  each  other, 

xxxix  4,8. 
their  changes    after  nativity, 

xxxix.  4,  8. 

their  changes  before  nativity, 
xxxix.  4,  .8. 


Animals,  lefs  liable  to   contagious  dii- 

eafes,  why,  xxxiii.  1,  5. 
lefs  liable   to   delirium  and  in- 

fanity,  why,  xxxiii.  1,5. 
eafier  to  preferve   than  to  re- 
produce, xxxvii. 
electricity,  xiv.  5. 
food,  diftafte  of,  xxxviii.  1. 
appetency,  xxxix.  4,  7. 
Animalcula,  xxxix.  1 1.  5. 

from  boiling  broth,  xxxix. 

11,1. 

Antipathy,  x.  2,  2. 
Appetites,  xi.  2,  2,  xiv.  8. 
Aphthae,  xxviii. 
Apoplexy,  xxxiv.  1,  7. 

not     from  deficient   irrita- 
tion, xxxii.  2,  1. 
Architecture,  xii.  3,3,  xvi.  10. 
Arts,  fine,  xxii.  2. 

Afparagus,  its  fmell  in  urine,  xxix. 
AfTociation  defined,  ii.  2,  11,  iv.  7,  v.  '2 
aflbciate  motions,  x. 
ftronger       than     irritative 

ones,  xxiv.  2,  8. 
formed      before      nativity,, 

xi.  3. 

with  irritative  ones,  xxiv.  8. 
with  retrograde   ones,:xxv 

7,  xxv.  10,  xxv.  1 J. 
difeafes  from,  xxxv. 
Aflhma,  xviii.  15. 
Attention,  language  of,  xvi.  8,  6,. 
Atrophy,  xxviii. 
Averiion,  origin  of,  xi.  2,  3. 

B 

Balance  ourfelves  by  vifiou,  xx.  1. 
Bandage  increafes    abforption,  xxxiii 

3,2. 

Barrennefs,  xxxvi.  2,  3. 
Battement  of  founds,  xx.  7. 


INDEX  TO  THE  SECTIONS.— PART  I. 


Bath,  cold.     See  Cold  Bath. 
Bath,  warm,  xxix,  4,  5. 
Beauty,  fenfe  of,  xvi.  6,  xxii.  2, 
Eile-du&s,  xxx. 

flones,  xxx.  8. 

regurgitates  into  the  blood,  xxiv. 

2,7. 

vomiting  of,  xxx.  3. 
Birds  of  paffage,  xvi.  12. 
nefb  of,  xvi.  1 3. 
colour  of  their  eggs,  xxxix.  5. 
Biting  in  pain,  xxxiv.  1,  3. 

of  mad  animals,  xxxiv.   1,  3. 
Black  fpots    on  dice  appear  red,  xl.  3. 
Bladder,  communication   of  with  the 

inteftines,  xxix.  3. 
of  fifli,  xxiv.   1 ,  4. 
Blood,  transfufion  of  in  nervous  fevers, 

xxxii.  4. 

deficiency  of,  xxxii.  2   and  4. 
from  the  vena  portarum  into 

the  inteftines,  xxvii.  2. 
its  momentum,  xxxii.  5,  2. 
momentum,  increafed  by  vene- 

feclion,  xxxii.  5,4. 
drawn  in  nervous  pains,  xxxii, 

5,  4. 

its  oxygenation,  xxxviii. 
Breathing,  how  learnt,  xv.  4. 
Breads  of  men,  xiv.   8. 
Brutes  differ  from  men,:xi.  2,  3,  xvi.  17. 

See  Animals. 

Buxton  bath,  why  it  feels  warm,  xii. 
2,  1,  xxxii.  3,  3. 


Capillary  veffels  are  glands,  xxvi.  1. 

Catalepfy,  xxxiv.  1 ,  5. 

Catarrh    from    cold  fldn,  xxxv.  1,  3. 

xxxv.  2,  3. 

from  thin  caps  in  fleep,xviii.l5. 
Catenation  of  motions  defined,  ii.  11, 

iv.  7. 

caufe   of  them,  xvii.  1,  3. 
defcribed,  xvii. 
continue  fome  time  after 
their   production,   xvii. 
1,3. 

voluntary  ones  difievered 
in  fleep,  xvii.  1,  12,  xvii. 
3,  13. 
Cathartics,   external,   their  operation, 

xxix.  7,  6. 

Caulation,  animal,  defined,  ii.  11,  iv.  7. 
Caufe  of  caufes,  xxxix.  4,  8. 
Caufes  inert  and  efficient,  xxxix.  12,  2. 
active  and  paffive,  xxxix.  12,  3. 
proximate   and  remote,  xxxix". 
If?,  4. 


Chick  in   the    egg,    oxygenation    pf, 

xxxviii.  2. 

Child  riding  on  a  ftick,  xxxiv.  2,  6. 
Chilnefs  after  meals,  xxi,  3,  xxxv.  1,1. 
Cholera,  cafe  of,  xxv.  1 3. 
Chyle,  xxxix.  11. 

Circulation  in  the  eye  vifible,  xl.  10,  4, 
Cold  in  the  head,  xii.  7,  5. 

perceived  by  the  teeth,  xxxii.  3. 

l,xiv.  6. 

air,  ufes  of   in  fevers,  xxxii.  3,  3. 
feet   produces    coryza,  xxxv.    2, 

3,  xxxv.  1,  3. 
bath,  why   it  ftrengthens,   xxxii. 

S,  2. 
fliort    and    cold  breathing   in  it, 

xxxii.  3,  2. 

produces  a  fever  fit,  xxxii,  3,  2. 
fit  of  fever    the   confequence    of 

hot  fit,  xxxii.  9,  3. 
bathing   in    pulmonary    haemor- 
rhage, xxvii.  1. 
fits  of  fever,  xxxii.    4,    xxxii.  9, 

xvii.  3,  3. 

not  a  flimulus,xxxii.  10. 
Comparing  ideas,  xv.  3. 
Confcioufnefs,  xv.  3, 4. 

in  dreams,  xviii.  13. 
Confumption,  its  temperament,   xxxi. 

1   and  2. 
of   dark-eyed    patients, 

xxvii.  2. 
of  light-eyed    patients, 

xxviii.  2. 

is  contagious,  xxxiii.  2,  7. 
Confent  of  parts.     See  Sympathy. 
Contagion,  xii.  3,  6,  xix.  9,  xxxiii.  2,  6, 

and  8,  xxii.  3,  3. 
does  not  enter  the  blood, 
xxxiii.   2,  10,  xxii.  3,  3. 
Contraction  and  attraction,  iv.  1. 

of   fibres   produces  fenfa,- 

tion,  iv.  5,  xii.  1,6. 
continues   fome   time,  xii. 

1,5. 
alternates  with  relaxation, 

xii.  1,  3. 
Convulfion,  xvii.    1,  8,  xxxiv.  1,1,  and 

4,  iii.  5,  8. 
of  particular  mufcles,  xvii. 

1,8. 

periods  of,  xxxvi,  3,  9. 
Colours  of  animals,   efficient  caufe  of, 

xxxix.  5,  1. 

of  eggs  from  female  imagina- 
tion, xxxix.  5, 1. 
of  the  choroid  coat  of  the  eye(, 

xxxix.  5, 1. 
of  birds'  nefts,  xvi.  13. 

Coryfca, 


INDEX  TO  THE  SECTIONS.— PAR  r ' 


Coryza.     See  Catarrh. 

Cough,    nervous,   periods    of,   xxxvi. 

3.  9. 

Cramp,  xviii.  15.xxiv.  1,  7. 
Critical  days    from  lunations,  xxxvi.  4. 
Cuckoo,  xvi.  13,  5. 


Darkifli  room,  why  we  fee  well  in  it, 

xii.  2,  1. 
Debility,  fenforial  and  ftimulatory,  xii. 

2,  1. 

direct    and    indirect  of    Dr. 
Brown,  xii.  2,  1,  xxxii.  3,  2. 
See  Weaknefs. 
from  drinking  fpirits,  cure  of, 

xii.  7,  8. 

in  fevers,  cure  of,  xii.  7,  8. 
Deliberations,  what,  xxxiv.  1. 
Delirium,   two   kinds  of,   xxxiii.   1,  4. 

xxxiv,  2,  2. 
cafes  of,  iii.  5,  8. 
prevented  by  dreams,  xviii.  2. 
Defire,  origin  of,  xi.  2,  3. 
Diabetes  explained,  xxix.  4. 

with  bloody  urine,  xxvii.  2. 
in  the  night,  xviii.  15. 
Diarrhoea,  xxix.  4. 
Digeftion,  xxxiii.  1,  xxxvii. 

ftrengthened      by     emetics, 

xxxv.  1,  3. 

ftrengthened      by      regular 

hours,   why,    xxxvi.    2,  1. 

Digitalis,  ufe  of  in  dropfy,  xxix.  5,  2. 

Diftention  acts  as    a   ftimulus,  xxxii.  4. 

See  Extenfion. 
DifHnguiftiing,  xv.   3. 
Diurnal  circle  of  actions,  xxv.  4. 
Doubting,  xv.  3. 
Dreams,  viii.  1,2,  xiv.  2,  5. 

their  inconfiftency,  xviii.  16. 
no  furprile  in   them,  xviii.  17. 
much  novelty  of  combination, 

xviii.  9. 

Dropfies  explained,  xxix.  5, 1. 
Dropfy  cured    by  infanity,  xxxiv.  2,  7. 

cure  of,  xxix.  5,  2. 
Drunkennefs.     See  Intoxication,  xxi. 

diminiflied     by      attention, 

xxi.  8. 

Drunkards  weak  till  next  day,  xvii.  1 , 7. 
ftammer    and   dagger,   and 

weep,  xii.  4,  1,  xxi.  4. 
fee    objects    double,    why, 

xxi.  7. 
become    delirious,     fleepy, 

ftupid,  xxi.  5. 
Byfpncea  in  cold  bath,  xxxii.  3,  2, 


Ear,  a  good  one,  xvi.  10. 

noife  in,  xx.   7. 

Eggs  of  frogs,  fifli,  fowl,  xxxix.  i, 
of  birds,  why  fpotted,  xxxix.  v 
with  double  yolk,  xxxix.  4,  4. 
Electricity,  xii.  1.  xiv.  9. 

jaundice  cured  by  it,  xxx.  2. 
animal,  xiv.  5. 
Embryon    produced     by     the    male, 

xx\ix.  2. 
confifts    of    a    living   fibre, 

xxxix.  4. 
abforbs  nutriment,   receives 

oxygen,  xxxix.  1. 
its    actions    and    fenfations, 

xvi.   2. 

Emetic,     See  vomiting. 
Emotions,  xi.  2,  2. 
Ennui,  or  tasdeum    vitae,   xxxiv.  2,  3, 

xxxiii.  1,  1,  xxxix.  6*. 
Epileptic  fits    explained,    xxxiv.  1,  4, 

xxvii.  2. 
in  fleep,  why,  xviii.   14. 

and  15. 

EqUinoxia!  lunations,  xxxii.  6. 
Excitability  perpetually  varies,  xii.  1,  7. 
fynonymous  to  quantity  of 
fenforial  power,  xii.  1,  7. 
Exercife,  its  ufe,  xxxii,  5.  3. 
Exertion    of   ienforial  power  defined, 

xii.  2,  1. 

Exiftence  in  fpace,  xiv.  2, 5. 
Extenfion,  fenfe  of,  xiv.  7. 
Eyes  become  black  in  fome    epilepfi  N, 
xxvii.  2. 

F 
Face,  flufliing  of   after    dinner,  xxxv. 

1,  1. 
why  nrft    affected    in  fmall-poi, 

xxxv.  1,  1. 

red  from  inflamed  liver,  xxxv.  2,  2. 
Fainting  fits,  xii.  5,  1 ,  xiv.  7. 
Fear,  language  of,  xvi.  8,  1. 
a  caufe  of  fever,  xxxii.  8. 
caufe  of,  xvii.  3,  7. 

Fetus.     See  Embryon,  xvi.  2,  xxxix.  I. 
Fevers,  irritative,  xxxii.  1. 

intermittent,  xxxii.  1,    xxxii.  3. 
fenfitive,  xxxiii.  1. 
not  an  effort  of  nature  for  re- 
lief, xxxii.  10. 
paroxyfms   of,  xii.  7,  1,  xii.  2, 

3,  xii.  3,  5. 
why    fome    intermit    and  not 

others,  xxxvi.  1. 
cold  fits  of,   xxxii.  4.    xxxii.  9, 
xvii.  3,  3. 

Fevers, 


'81' 


INDEX  TO  THE    SECTIONS-— PART  I. 


Fevers,  periods  of,  xxxvi.  3. 

have  folar    or    lunar    periods, 

xxxii.  6. 
fource  of  the     fymptoms    of, 

xxxii.  1. 
proftration  of  flrength  in,   xii. 

4,  1,  xxxii.  3,  2. 
cure  of,  xii.  6,  1. 
how  cured  by  the  bark,  xii.  3,4. 
cured    by    increafed    volition, 

xii.  2,  4,  xxxiv.  2,  8. 
beft   quantity   of   ftimulus   in, 

xii.  7,  8. 
Fibres.     See  Mufcles. 

their  mobility,  xii.  1,  7,  xii.  1,1. 
contractions  of,  vi.  xii.  1,  1. 
four  claffes  of  their  motions,  vi. 
their  motions  diftinguflied  from 

fenforial  ones,  v.  3. 
Figure,  xiv.  2,  2,  iii.  1. 
Fifli,  their  knowledge,  xvi.   14. 
Foxglove,  its  ufe  in  dropfies,  xxix.  5,  2. 

overdofe  of,  xxv.   1 7. 
Free-will,  xv.  3,  7. 

G 

Gall-ftone,  xxv.  17.     See  Bile-fhmes. 
Generation,  xxxiii.  1,  xxxix. 
Gills  of  fifli,  xxxviii.  2. 
Glands, xxii.  l.conglobateglands,xxii.2. 
have    their    peculiar    flimulus, 

xi.  ]. 

their  fenfes,  xiv.  9,  xxxix.  6. 
invert  their  motions,  xxv.  7. 
increafe  their   motions,  xxv.  7. 
Golden  ruleforexhibitingwine,xii.  7,8. 
for  leaving  offwine,  xii.  7,  8. 
Gout  from  inflamed   liver,  xxxv.  2,  2. 

xviii.  15,  xxiv.  2,  8. 
in  the  ftomach,  xxiv.  2,  8,  xxv.  1 7. 
why  it  returns  after  evacuations, 

xxxii.  4. 
owing  to  vinous  fpirit  on  Iy,xxi.  10. 

periods  of,  xxxvi.  3,  6. 
Grinning  in  pain,  xxxiv.  1,3. 
Gyration  on  one  foot,xx.  5  and  6. 

H 

Habit  defined,  ii.  11,  iv.  7. 
Haemorrhages,  periods  of,  xxxvi.  3, 11. 
from  paralyfis   of  veins, 

xxvii.  1   a.nd  2. 
Hair  and  nails,  xxxix.  3,  2. 
colour  of,  xxxix.  5.  1. 
Harmony,  xxii.  2. 
Head-achs,  xxxv.  2;  1, 
Hearing,  xiv.  4. 


Heat,  fenfe  of,  xiv.  6,  xxxii.  S,  1. 

produced  by  the  glands,  xxxii,  b. 
external  and  internal,  xxxii.  3,  1. 
atmofphere  of  heat,  xxxii.  3,  1. 
increafes  during  fleep,  xviii.  15. 
Hemicrania,  xxxv.  2,  1. 

from  decaying  teeth,  xxxv.  2.  i. 
Hepatitis,  caufe  of,  xxxv.  2,  3. 
Hereditary  difeafes,  xxxix.  7,  6. 
Hermaphrodite  infe&s,  xxxix.  5. 
Herpes,  xxviii  2. 

from  inflamed kidney,xxxv.  2,2" 
Hilarity  from  diurnal  fever,  xxxvi.  3,1. 
Hunger,  fenfe  of,  xiv.  8. 
Hydrophobia,  xxii.  3,  3. 
Kypochondriacifm,  xxxiii.  1,  1,  xxxiv. 
2.  3. 

I 
Ideas  defined,  ii.  vi.  2,  7. 

are  motions  of  the  organs  of  fenfe, 

iii  4,    xviii.  5,  xviii.    10,  xviii.  6. 

analogous    to   mufcular  motions, 

iii.  5. 

continue  fome  time,  xx.  6. 
new  ones    cannot    be    invented, 

iii.  6.    1. 

abftrafted  ones,  iii.  6,  4,  xv.  5. 
inconfiftent  trains  of,  xviii  16. 
perifh  with  the  organ  of  fenfe, 

iii.  4,  4. 
painful  from  inflammation  of  the 

organ,  iii.  5,  5. 
irritative  ones,  vii.  1,4,  vii  3,  2, 

xv.  2.  xx.  7. 
of  refemblance,  contiguity,  cauf- 

ation,  viii  3,  2,  x    3  3, 
refemble    the  figure,     and  other 
properties  of  bodies,  xiv  2.  2. 
received  in  tribes,  xv.  1 
of  the  fame  fenfe  eafier  combin- 
ed, xv.  1,  1. 

of  reflection,  xv  1,  6,  ii.  12. 
Ideal  prefence,  xv.  1,  7. 
Identity,  xv.  3,  5,  xviii.  13. 
Iliac  paflion,  xxv.  15. 
Imagination,  viii.  1,  2,  xv.  1,  7,xv.  2,  2, 
of    the    male    forms    the 

fex,  xxxix.  6. 

Immaterial  beings,  xiv.  1,  xiv,  2,  4. 
Imitation,  origin  of,  xii.  3,  3>,  xxxix.    5, 

xxii.  3,  xxi.  7 
Impediment  of  fpeech,  xvii.  1,  10.  xvii. 

2,10. 

Infedlion.     See  Contagion. 
Inflammation,  xii  2,  3,  xxxiii.  2, 2. 

great  vafcular  exertion 
in,  xii.  2,  1. 

Inflammation, 


INDEX  TO  THE  SECTIONS.— PART  I. 


Inflammation  not  from  pains  from  de- 

fect of  ftimulus,  xxxiii. 

2,3. 
of  parts    previoufly  in- 

fenfible,  xii.  3,  7. 
often    diftant     from    its 

caufe,  xxiv.  8. 
obferves       folar      days, 

xxxii.  6. 
of  the  eye,  xxxiii.  3,  1  . 


Life,  long,  art  of  producing,  xxxvii. 
Light  has  no  momentum,  iii.  3,1. 
Liquor  amnii,  xvi.  2,  xxxviii.  3,  xxxix. 

1,  1. 

is  nutritious,  xxxviii.  3. 
frozen,  xxxviii.  3. 
Liver,  paralyfis  of,  xxx.  1,  4. 

large  of  geefe,  xxx.  1,  6. 
Love,  fentimental,  its  origin,  xvi.  6. 

animal,  xiv.  8,  xvi.  5. 

of  the  bowels  prevented     Lunar  periods  affect   difeafes,  xxxii.  6. 
by     their     continued     Luft,  xiv.  8,  xvi.  5. 
a&ion  in  deep,  xviii.  2.     Lamphatics,  paralyfis  of,  xxviii.    See 
Abforbents. 


Inoculation  with  blood,  xxxiii.  2,  10. 
Infane  people  ,their  great  ft  rength,  xii.  1  . 
Infanity(fee  Madnefs)  pleafureable  one, 

xxxiv.  2,  6. 

Infe&s,  their  knowledge,  xvi.  15  &  16. 
in  the  heads  of  calves,  xxxix.  1  . 
clafs  of,  xxxix.  4,  8. 
Inftin&ive  actions  defined,  xvi.  1. 
Inteftines,  xxv.  3. 

Intoxication  relieves  pain,  why,  xxi.  3. 
from  food   after   fatigue, 

xxi.  2. 

difeafes  from   it,   xxi.  10. 
See  Drunkennefs. 
Intuitive  analogy,  xvii.  3,  7. 
Invention,  xv.  3,  3. 
Irritability     increafes    during     fleep, 

xviii.  15. 
Itching,  xiv.  9. 

J 
Jaw,  locked,  xxxiv.  1,  5. 


M 

Mad-dog,  bite  of,  xxii.  3,  3. 
Madnefs,  xxxiv.  2,  1,  xii.  2,  1. 
Magnet! fm,  xii.  1,1. 
MagnifyingobjecTts,newway  of,xl.  10,5. 
Male  animals  have  teats,  xxxix.  4,  8. 

pigeons  give  milk,  xxxix.  4,  8. 
Man   diltinguifhed   from  brutes,  xi.  2, 

3,  xvi.  17. 

Material  world,  xiv.  1,  xiv.  2, 5,  xviii.  7. 
Matter,  penetrability  of,  xiv.  2,  3. 

purulent,  xxxiii.  2,  4. 
Meafles,  xxxiii.  2,  9. 
Membranes,  xxvi.  2. 
Memory  defined,  ii.  2, 10,  xv.  1 ,  7,  xv.  3. 
Menftruation  by  lunar  periods,  xxxii.6. 
Microfcopic  animals,  xxxix.  11,5. 

vegetables,  xxxix.  11,  1. 
Mifcarriage  from  fear,  xxxix.  6,  5. 
Mobility  of  fibres,  xii.  1,  7. 


Jaundice  from    paralyfis  of  the  liver,     Momentum  of  the  blood,  xxxii.  5,  2 


xxx.  2. 

cured  by  electricity,  xxx.  2. 
Judgment,  xv.  3. 

K 
Knowledge  of  various  animals,  xvi.  1  1. 

L 

Lacrymal  fack,  xvi.  8,  xxiv.  2  and  7. 
Ladteals,  paralyfis  of,  xxviii.     See  Ab- 

forbents. 
Lady    playing    on    the    harpfichord, 

xvii.  2. 
diftrefled  for    her  dying  bird, 

xvii.  2.  10. 

Language,  natural,  itsorigin,xvi.7  &  8. 
of  various  paflions  defcrib- 

ed,  xvi.  8. 
artificial,  of  various  animals, 

xvi.  9. 

theory  of,  xxxix.  8,  3. 
Lapping  of  puppies,  xvi.  4. 
Laughter  explained,  xxxiv.  1,4. 
from   tickling,     xvii. 

xxxiv.  1,  4. 

from  frivolous  ideas,  xxxir. 
1,4,  xviii.  12. 


fometimes     increafed    by 
venefe&ions,  xxxii.  5,  4 
Monfters,  xxx.  4,  4,  and  5,  2. 

without  heads,  xxxviii.  3. 
Moon  and  fun,  their  influence,  xxxii.  6. 
Mortification,  xxxiii.  3,  3. 
Motion  is  either  caufe   or  effect,!,  xiv, 

2,2. 

primary  and  fecondary,  i. 
animal,  i.  iii.  1. 
propenfity  to,  xxii.  1. 
animal,    continue      fometiipe 
after  their  production,  xvii. 
1,3. 
defined,  a  variation  of  figure, 

iii.  1,  xiv.  2,  2,  xxxix.  7. 
Mucus,  experiments  on,  xxvi.  1. 

fecretion  of,  xxvi.  2. 
Mules,  xxxix.  4,  5  and  6,  xxxix.  5,  2. 
Mule  plants,  xxxix.  2. 
Mufcae  volitantes,  xl.  2. 
3,  5,    Mufcles  conflitute   an  organ  of  fenfe, 

xiv.  7,  ii.  3. 

ftimiilatedby  extenfion,  xi.  1, 
xiv.  7. 

Mufcles 


86 


INDEX  TO  THE  SECTIONS.— PART.  I. 


Mufcles  contract  by  fpirit.of  animation, 

xii.  1,1,  and  3. 
Mufic,  xvi.  10,  xxii.  2. 
Mufical  time,  why  agreeable,  xii.  3,  3. 

N 

Naufea,  xxv.  6. 
Nerves  and  brain,  ii.  2}  3. 

extremeties  of,  form  the  whole 

fvftem,  xxxvii.  3. 
are  not  changed  with  age,xxxvii.4. 
Nervous  pains  denned,  xxxiv.  1,1. 
Number  defined,  xiv.  2,  2. 
Nutriment  for  the  embryon,  xxxix.  5,  2* 
Nutrition  owing  to  ftimulus,  xxxvii.  3. 
by  animal  fele&ion,  xxxvii.  3. 
when  die    fibres  are  elongat- 
ed, xxxvii.  3. 
like  inflammation,   xxxvii.  3. 

O 
Objedls  long  viewed  become  faint,  iii. 

3,2. 

Ocular  fpedlra,  xl. 
Oil  externally  in  diabetes,  xxix.  4. 
Old  age  from  inirritability,  xxxvii. 
Opium  is  ftimulant,  xxxii.  2,  2. 

promotes   abforption    after  e- 

vacuation,  xxxiii.  2,  10. 
in  increafing  dofes,  xii.  3,  1. 
Organs  of  fenfe,  ii,  2,  5. 

when  deftroyed  ceafe   to  pro- 
4          duce  ideas,  iii.  4,  4. 
Organic  particles  of  BufFon,   xxxvii.  3. 

xxxix.  3,  3. 
Organ  pipes,  xx.  7. 
Oxygenation  of  the  blood,  xxxviii. 

P 

Pain  from  excefs  and  defect  of  motion, 
iv.  5,  xii.   5,  3,  xxxiv.  1,  xxxv. 
2,1. 
not  felt  during  exertion,  xxxiv. 

1,2. 

from  greater   contraction  of  fi- 
bres, xii.  1,  6. 
from  accumulation  of  fenforial 

power,  xii  5,  3,  xxiii.  3,  1. 
from  light,  pretfure,  heat,  cauf- 

tics,  xiv.  9. 

in  epilepfy,  xxxv,  2,  1. 
diftant  from  its  caufe,  xxiv.  8. 
from  ftone  in  the  bladder,  xxxv. 

2,1. 
of  head  and  back  from  defecl  of 

heat,  xxxii.  3. 
from  a  gall-ftone,  xxxv.  2,  l,xxv. 

17. 

of  the  ftomach  in  gout,  xxv.  17. 
of  fhoulder  inhepatites,xxxv.2,4. 
produces  volition,  iv.  6. 


Palenefs  in  cold  fit,  xxxii,  3,  2. 
Paliies  explained,  xxxiv.  ' ,  7. 
Paralytic  limbs  ftretch  from  irritation, 

vii.  1,  3. 
patients    move   their  found 

limb  much,  xii.  5,  1. 
Paralyfis  from  great  exertion,  xii.  4.  6, 
from  lefs  exertion,  xii.  5,  6. 
of  the  lacteals,  xxviii. 
of  the  liver,  xxx.  4. 
of  the  right  arnij  why,  xxxiv. 

1,7. 

of  the  veins,  xxvii.  2. 
Particles  of  matter  will  not  approach, 

xii.  1,  1. 
Paflions,  xi.  2,  2. 

connate,  xvi.  1. 
Pecking  of  chickens,  xvi.  4. 
Perception  defined,  xv.  3,  1,  ii.  2,  8. 
Periods  of   agues,   how  formed,  xxxii. 

3,4. 

of  difeafes,  xxxvi. 
of  natural  actions  and  of  dif- 

eafed  actions,  xxxvi. 
Perfpiration  in  fever-fits,  xxxii.  9.    See 

Sweat. 

Petechise,  xxvii.  2. 
Pigeons  fecrete  milk  in  their  flomachs, 

xxxii.  4,8. 
Piles,  xxvii.  2* 
Placenta  a  pulmonary  organ,  xxxviii . 

2. 
Pleafure  of  life,  xxxiii.  1 ,  xxxi  x.  8. 

from  greater  fibrous    contrac- 
tions, xii.  1 ,  6. 
what  kind    caufes    laughter, 

xxxiv.  1,  4. 
what  kind  caufes  fleep,  xxxiv  . 

1.  4. 
Pleurify,  periods  of,  xxxvi.  3,  7. 

caufe  of,  xxxv.  2,  3. 
Prometheus,  (lory  of,  xxx.  3. 
Proftration  of  ftrength  in   fevers,  xii. 

4.  1. 

Pupils  of  the  eyes  large,  xxxi.  1. 
Pulfe  quick  in  fevers  with  debility,  xii. 

1,  4,  xii.  5, 4,  xxxii.  2,  1. 
in  fevers  with  ftrength,  xxxii.  2» 
from  defecl  of  blood,  xxxii.  2,3. 

xii.  1.  4. 
weak  from  emetics,  xxv.  17. 

Q 

Quack  advertifments  injurious.     Pref- 
ace. 
Quadrupeds  have  no    fanguiferous  lo- 

chia,  xxxviii.  2. 
having   nothing'  fimilar  to 
the  yolk  ot  egg,  x^xix  1 . 
Raphania, 


INDEX  TO  THE  SECTIONS— PART  I. 


8.7 


Raphania,  periods  of,  xxxvi.  3,  9. 
Reafon,  ix.  1,2,  xv.  3. 
Reafoning,  xv.   3. 

Recolle&ion,  ii.  10,  ix.  1,  2,  xv.  2,  3. 
Relaxation  and  bracing,  xxxii.  3,  2. 
Repetition,  why  agreeable,  xii.  3,  3, 

xxii.  2. 
Refpiration     affe&ed      by    attention, 

xxxvi.  2,  1. 

Reftlefliiefs  in  fevers,  xxxiv.  1 ,  2. 
Retrograde   motions,  xii.  5,  5.  xxv.  6, 

xxix.  11. 

of  the  ftomach,  xxv.  6. 
of  the  {kin,  xxv.  9. 
of  fluids,  how  diftinguiflied, 

xxxix.  8. 

how  caufed,  xxix.  1 1.  5. 
Retrograde  vegetable  motions,  xxix.  9. 
Retina  is  fibrous,  iii.  2,  xl.  1. 

is  a&ive  in  vifion,  iii.  3,  xl.  1. 
excited  into  fpafmodic  motions, 

xl.  7. 
K  fenfible  during  fleep,  xviii.  5, 

xix.  8. 
Reverie,  xix,  1,  xxxiv.  3. 

cafe  of  a  fleep-walker,  xix.  2. 

is  an    epileptic  difeafe,  xix.  9. 

Rhymes   in    poetry,  why    agreeable, 

xxii.  2. 

Rheumatifm,  three  kinds   of,   xxvi.  3. 
Rocking  young  children,   xxi.  4. 
Rot  in  Sheep,  xxxii.  7. 
Ruminating  animals,  xxv.  1. 

S 

Saliva  produced  by  mercury,  xxiii. 
by  food,  xxiii.  1. 
by  ideas,  xxiii.  2  and  5. 
by   diibrdered    volition,  xxiii.  7. 
Scirrhous  tumours  revive,  xii.  2, 2. 
Screaming  in  pain,  xxiiv.  1,  2. 
Scrofula,  its  temperament,  xxxi.  1. 

xxviii.  2,  xxxix.  4,  5. 
Scurvy  of  the  lungs,  xxvii,2. 
Sea  ficknefs,  xx.  4. 

flopped  by  attention,  xx.  5. 
Secretion,  xxxiii.  1,  xxxvii. 

increafed  during  lleep,  xviii.  16. 

Seeds  require  oxygenation,    xxxviii.  2. 

Senfation  defined,  ii.2,  9,  v.  2,  xxxix.8,4. 

difeaies  of,  xxxiii. 

from    fibrous    contractions, 

iv.  5.  xii.  1,  6. 

in  an  amputated  limb,  iii.  7,3. 
affedls  the  whole  fenforium, 

xi.  2. 

produces  volition,  iv  6. 
3eniiblity  increafes  during  fleep,  xviii. 
15. 
VOL  T.  Y»  T  v 


Senfitive     motions,    viii.     xxxiii.     2, 

xxxiv.  1. 
fevers  of  two  kinds,  xxxiii. 

1,2. 

ideas,  xv.  2,  2. 
Senforium  defined,  ii.  2,  I. 
Senfes  correct  one  another,  xviii  7. 

diftinguiflied    from    appetites, 

xxxiv.  1,  1. 

Senforiai  power.     See  Spirit   of  Ani- 
mation, 
great  expenfe  of  in  the  vital 

motions,  xxxii.  3,  2. 
two  kinds  of  exerted  in  fen- 
fitive  fevers,  xxxiii.  1,3. 
powers  defined,  v.  i, 
motions    diftinguiflied  from. 

fibrous  motions,  v.  3. 
not    much    accumulated  in 

fleep,  xviii.  2. 
powers,  accumulation  of,  xii. 

5,1. 

exhauftion  of,  xii.  4,  1. 
wafted  below  natural  in  hot 

fits,  xxxii.  9,  3. 
lefs    exertion    of,    produces 

pain,  xii.  5,  3. 

lefs  quantity  of  it,  xii.  5,  4. 
Senfual  motions     diftinguiflied    from 

mufcular,  ii.  7. 

Sex  owing  to  the  imagination  of  the 
father,  xxxiv.  5,  xxxix.  7,  6,  xxxix. 
6,  3,  xxxix.  6,  7. 

Shingles  from  inflamed  kidney,  xxxv.2,2. 
Shoulders  broad,  xxxi.  1,  xxxix.  7,  6. 
Shuddering  from  cold,  xxxiv.  1,  1  &2. 
Sight,  its  accuracy  in  men,  xvi.  6. 
Skin,  fcurf  on  it,  xxvi.  1, 
Sleep  fufpends  volition,  xviii.  1. 
defined,  xviii.  21. 
remote  caufes,  xviii.  20. 
fenfation  continues  in  it,  xviii.  2. 
from  food,  xxi.  1. 
from   rocking,  uniform  founds, 

xxi.  1. 

from  wine  and  opium,  xxi.  3. 
why  it  invigorates,  xii.  5,  1. 
pulfe  flower  and  fuller  in,  xxxii. 

2,2. 

interrupted,  xxvii.  2. 
from    breathing    lefs    oxygene, 

xviii.  2O. 
from  being   whirled  on  a  mill- 

ftone,  xxiii.  20,  • 

from  application  of  cold,  xviii.  2O. 
induced  by  regular  hours,  xxxvi. 

2,  2. 

Sleeping  animals,  xxi.  2,  2. 
Sleep-walkers,     See  Reverie,  xix,  1. 
Small-pox* 


INDEX  TO  THE    SECTIONS.— PART  1. 


$mall-pox,  xxxiii.  2,  6,  xxxiv,  6, 1. 

„  eruption  firft   on  the  face, 
why,   xxxv.    1,  1,  xxxiii. 
2,10. 
the   blood   will  not  infetfl, 

xxxiii.  2,  10. 
obeys  lunations,  xxxvi.  4. 
Smell,  xiv.  5,  xvi.  5. 
Smiling,  origin  of,  xvi.  8,  4. 
Solidity,  xiv.  2,  1. 

Somnambulation.     See  Reverie,  xix.  1. 
Space,  xiv.  2,  2. 
Spafm,  doctrine  of,  xxxii.  10. 
Spectra,  ocular,  xl. 

miftaken  for  fpecTres,  xl.  2. 
vary  from  long  infpedtion,  iii. 

3,  5. 
Spirit   of  animation.       See    Senforial 

Power. 

of  animation  caufes  fibrous  con- 
traction, iv.  2,ii    l,xiv.  2?  4. 
polTefles  folidity,figure,and  oth- 
er properties   of  matter,  xiv. 
o  3^ 

Spirits  and  angels,  xiv.  2,  4. 
Stammering,    explained,    xvii.    1,  10, 

xvii.  2,  10. 

Stimulus  defined,  ii.  2, 13,  iv.  4,  xii.  2,1. 
of  various  kinds,  xi.  1. 
with  leflened  effect,  xii.  3,  1. 
with  greater  effect,  xii.  3,  3. 
ceafes  to  produce   fenfation, 

xii.  3,3, 
Stomach  and  inteftines,  xxv. 

inverted    by    great  ftimulus, 

xxv.  6. 

its  actions   decreafed  in  vom- 
iting, xxxv.  1,  3. 
a  blow  on  it  occafions  death, 

xxv.  17. 

Stools  black,  xxvii.  2. 
Strangury,  xxxv.  2,  1. 
Suckling  before  nativity,  xvi. 4. 
Suckling  children,  fenfe  of,  xiv.  8. 
Suggeftion  defined,  ii.  10,  xv.  2,  4. 
Sun  and  moon,  their  influence,  xxxiUJ. 
Surprife,  xvii.  3,  7,  xviii.  17. 
Sufpicion  attends  madnefs,  xxxiv.  2,  4, 
Swallowing,  act  of,  xxv.  1,  xvi  4. 
Sweat,  cold,  xxv    9,  xxix.  6. 

in  hot  fit  of  fever,  xxxii.  9- 
in  a  morning,  why,  xviii.  15. 
Sweaty    hands    cured  by    lime,  xxix. 

4,9. 
Swinging  and  rocking,  why  agreeable, 

xxi.  3. 

Sympathy,  xxxv.  1, 
Syncope,  xii.  7, 1 ,  xxxiv.  1  ?  6, 


Tredium  vitre.     See  Ennui. 
Tape-worm,  xxxix.  2,  3. 
Tafte,  fenfe  of,  xiv.  5. 
Tears,  fecretion  of,  xxiv. 
from  grief 5  xvi.  8.  2. 
from  tender  pleafure,  xvi.  8,  5. 
from  ftimulus  of  nafal  duet,  xvi 

8,  xxiv.  4. 
by  volition,  xxiv.  6. 
Teeth  decaying  caufe   headachs,  xxxv 

2,1. 

Temperaments,  xxxi. 
Theory  of  medicine,  wanted.    Preface, 
Thirft,fenfeof,xiv.8. 

why  in  dropfies,  xxix*  5. 
Tickle   themfelves,    children    cannot* 

xvii.  3,  5. 
Tickling,  xiv.  9. 
Time,  xiv.  2,  2,  xviii.  12. 
lapfe  of,  xv.  3, 6. 
poetical  and  mufical,  why  agree- 
able, xxii.  2. 
dramatic,  xviii.  12. 

Tooth-edge,  xvi.  10,  iii.  4,  3,  xii.  3,  3. 
Touch,  fenfe  of,  xiv  2,  1. 

liable  to  vertigo,  xxi.  9. 
of  various  animals,  xvi.  6. 
Trains  of  motions  inverted,  xii.  5,  5. 
Transfufion  of  blood  in  nervous  fever, 

x  .xii.  4. 

Tranflations  of  matter,  xxix.  7. 
Typhus,  beft    quantity  of  ftimulus  in, 

xii.  7,  8. 

periods    of,     obferve     lunar 
days,  xxxii.  6. 

IT 

Ulcers,  art  of  healing,  xxxii.  3,  2. 

of  the  lungs,  why  difficult  to 

heal,  xxviii.  2. 

Uniformity  in  the  fine  arts,  why  agree- 
able, xxii.  2. 
Urine  pale  in  intoxication,  xxi.  6. 

paucity  of     in    anafarca,  why, 

xxix.  5. 
its    pafTage    from   inteftines  t» 

bladder,  xxix.  3. 
copious  during    fleep,  xviii.  15. 

V 
Variation,  perpetual,  of  irratibility,  xii. 

2,1. 
Vegetable   buds  are   inferior  animals , 

xiii.  1. 
exactly    refemble    their 

parents,  xxxix. 
poflefs     fenfation    and 
YQlition,  xiii.  2. 

Vegetable 


INDEX  TO  THE  SECTIONS — PART  I. 


89 


Vegetable  buds  have  aiTociate  and  re- 
trograde motions,  xiii. 
4,  xxix.  9. 
their  anthers  and  fligmas 

are  alive,  xiii.  5. 
Vegetables   have   organs   of  fenfe  and 

ideas,  xiii.  5. 
contend   for  light    and  air 

xxxix.  4,  8. 

duplicature    of   their  flow- 
ers, xxxix.  4,  4. 
Veins  are  abforbents,  xxvii.  1 . 

paralyiis  of,  xxvii.  1 . 
Venereal  orgafm  of  brutes,  xxxii.  6. 
Venefedlion  in  nervous  pains,  xxxii.  5,4. 
Verbs  of  three  kinds,  xv.  3,  4. 
Verfes,  their  meafure,  xxii.  2. 
Vertigo,  xx.  defined,  xx.  11. 

in  looking  from  a  tower,  xx.  1 . 
in  a  fliip  at  fea,  xx.  4. 
of  all  the  fenfes,  xxi.  9. 
by  intoxication,  xxxv.  1,  2. 
Vibratory  motions  perceived  after  fail- 
ing, xx.  5,  xx.  10. 

Vinegar  makes   the  lips  pale,  xxvii.  1. 
Vis  medicatrix  of  nature,  xxxix.  4,  7. 
Vifion,  fenfe  of,  xiv.  3. 
Volition  defined,  v.  2.  xxxiv.  1. 

affecb    the  whole   fenforium, 
xi.  2. 


Volition,  difeafes  of,  xxxiv. 
Voluntary,  x.  2,  4. 

motions,  ix.  xxxiv.  1. 
ideas,  xv.  2,  3. 

criterion  of,  xi.  2,  3, 

xxxiv.  1. 
Vomiting  from  vertigo,  xx.  8. 

from    drunkennefs,    xx,     8, 

xxi,  6. 

by  intervals,  xxv.  8. 
by    voluntary    efforts,   xxv. 

6. 

of  two  kinds,  xxxv.  1,  3. 
in   cold    fit    of  fever,  xxxii. 

9,1. 
flopped  by  quickfilver,  xxv. 

16. 
weakens   the  pulfe,  xxv.  1 7. 

W 

Waking,  how,  xviii.  1 4. 
Walking,  how  learnt,  xvi.  3. 
Warmth  in  fleep,  why,  xviii.  15. 
Weaknefs  defined,  xii.   1,  3,  xii.  2.  1, 

xxxii.  8,2. 

cure    of,  xii.    7,  8.     See  De- 
bility. 

Wit  producing   laughter,   xxxiv.  1,4. 
World  generated,  xxxix.  4,  8. 
Worm,  fluke,  xxxii.  7. 


£ND  OF  INDEX  TO  PART  L 


PARTJI.  and  the  Index  to  it,  compofe  the  SECOND  VOLUME. : 


INDEX 


OF  THE 

ARTICLES  OF  PART  THIRD. 


LBSORPTION,  iv.  2,  1. 

cutaneous,  mucous,  cellu- 
lar, iv.  2,  2. 
of  the  veins,  iv.  2,  4,' 
of  inflamed  vefiels,  iv.  2, 

4,  3. 
of  inteilines  and  liver,  iv. 

2,  5. 

of  venere  -1  ulcers,  iv,  2.  7. 
not    increased    by     cold, 

iv.  2,  1. 
increafed  by   opium  after 

evacuation,  ii.  2,  1. 
by  faline  bath,  iv.  2,  3,  8. 
by  abftinence   from  fluids, 

iv.  2,  3,  9. 
Acacia,  iv.  3,  5,  2. 
Acids  auftere,  iv.  2,  1,  2,  iv  3,  1. 

vegetable,  fweet,vii  3,4,iv.2, 1,2. 
mineral,  vii.  3,  6. 
Acrid  plants,  iv.  2, 4 
Agriculture,  i.  2,  3,  7. 
Agues,  three   kinds,  iv.  2,  3, 2,  iv.  2, 5, 

iv.  2,  6,  8. 
Air  nourishes,  i.  2, 5. 

warm  bath  of,  iv.  2,  3, 8. 
Alcali  vol.  iii.  3,  3. 
Alcohol,  ii   2,  1.  v.  2,  4. 
Almond,  bitter,  ii.  3,  1? 
Althsea,  iii.  3,  3,  3. 
Alium,  iii.  3,  3. 

Aloe,  iii.  2  5,iii  2,  7,  iii.  3,  5,  5,  vi.  2,5. 
Alum,  iii.  2, 1,  iv.  2,  i,  iv.  2,  5,  2,iy.  3, 

5,3. 

to  purify  water,  i.  2,  4,  2. 
Amalgama  in  worms,  vii.  2,  2. 
Amomum  zinziber,  iii.  3, 1. 
Amber,  oil  of,  vi.  3.  4. 
Ammoniac  gum,  vi.  3,  1,  iii.  3,  3. 
fait  or  fpiritj  iii.  3,  3. 


Anarfarca,  warm  bath  in,  ii.  2,  2,  iv.  V.  „ 

3,  8 

Anchovy,  iii.  2,  1,  iii.  3,  1,  4. 
Animal  food,  i.  2,  1,  1. 
Antimony    prepared,  iii.  S,  1,  5,  iii.  2, 

l,iv.  1,  10. 
Anthemis  nobilis,  iv.  3, 3. 

pyrethrum,  iii.  3,  2, 
Anxiety,  v.  2,  4 

Apium,  petrofelinum,  iii.  3,  4,  4. 
Apoplexy,  iv.   2,  11* 
Arifloiochia  ferpentaria,  iii.  5,  1. 
Armenian  bole,  vi.  2,  3,vi    3,  5,  3. 
Arfenic  in  ague,  iv.  2,  6,  8,  iv.  3,x. 

faturated  folution  of,iv.2,  vi.  $. 

in  itch,  iv,  2,  9. 

how  it  acfts,  iv.  2,  6,  9. 

how  todetedl  it,  iv.  2,  6,   10. 
Artemifia  maritima,  iv.  3,  3, 
abfynthium,  iv.  3,  3. 
fantonicum,  iv.  3,  S. 
Artichoke-leaves,  iv.  3,  3. 
Afafoetida,  ii.  3,  vi.  3,  1. 
Afarum  Europeum,  v.  3,  3. 
Afcarides,  vii.  1,  2,  iii.  2,  9,  7. 
Afparagus,  iii.  3,  4,  4. 
Aflragalus  trapacantha,  iii.  3,  3,  5. 
Atropa  belladonna,  ii.  3,  1. 
Azote,  i.  2, 5. 

B 

Balfams  diuretic,  iii.  2,  4. 
Bandagespromoteabforption,iv.  2,  10. 
Bark,  Peruvian,  iv.  2,  2. 

long  uled  noxious,  iv.  2,  1 1. 
Barley,  iii.  3,  3,  3. 

Bath,  warm,  ii.  2,   2,  1,  iiL  3,  1,  6.  ii 
3,  3,  4,  iii.  2,  3,  3. 

faline,  iv.  2,  3,  8. 

of  warm  air,  iv.  2, 3,  8. 

ttiik 


INDEX    OF  THE  ARTICLES — PART  IIL 


Bath  of  fleam,  iv.  2,  3,  8. 
cold,  vii   2,  3. 
nutritive,  i.  2,  6,  1. 
Benzoin,  iii.  3,  3 
Bile  of  animals,  iii.  2,  5,  2. 

dilute  (late  of,  iv.  2,  6  $ 

Blifters,  how  they  act,  iii   2,  1,  10. 

cure  heart  burn,  iii.  2,  1,  10. 
ftop  vomiting,  vi    2,  2. 
produce    expectoration,  iii.  2, 

3,2. 
increafe   perfpiration,  iii.  2,  1, 

10 

Blood,  transfufion  of,  i.  2,  6,  2. 
Bog-bean,  iv.  3,  3. 
Bole  armenian,  iv.  2,  5,  3. 
Bone-afties,  iv.  3,  5,  3. 
Bowels,  inflammation  of,  v.  2,  2,  2. 
Bryony,  white,  iii.  3,  8. 

as  a  blifter,  iii.  2,  9. 
Butter,  i,  2,  3,  2. 
Butter-milk,  i.  2,  2,  2. 


Cabbage-leaves,  vii.  1,2. 
Calcareous  earth,  i.  2,  4,  3. 
Calomel,  iii.  2,  5,  vi.  2,  5. 

in  enteritis,  v.  2,  2,  2. 
Camphor,  iii   3,  1. 
Cnnella  alba,  iii   3,  1. 
Cantharides,  iii.  2,  6,  iii.    2,  8,  v.  2,  4, 

vi.  2,4. 
Capillary  action  fncreafed  by  tobacco, 

iv.  2,  3,  7. 
Capficum,  iii.  3,  1. 
Carbonic  acid  gas,  vii.  2,  6. 
Cardamomum,  iii.  3,   1. 
Caryophyllus  aromat.  iii.  3,  1. 
Cardamine,  iv.  3,  4. 
Caffia  fiftul.  iii.  3,  5,  1. 
fenna,  iii.  3,5,  5. 
Caftor,  vi.  2,  1.  vi.  3,  1. 
Cathartics,  mild,  iii.  2,  5, 

violent,  v.  2,  2. 

CerufTa  in  ulcers,  iv.  2,  9,  iv.  2,  7. 
Chalk,  iv  3,5,  3. 

Chalybeates,iv    3,  4,  2,  iv.  3,  6,  6. 
Chalybeate  powder,  iv.  2,  6,  6. 
Cheefe,  i.  2,2,3. 
Cherries,black,ii.  2,  1,  8. 
Chlorofis,  iv.  2,  6,  5. 
Cicuta,  ii.  3,  1. 
Cinchona,  iv.  2,  2. 
Cinnamon,  Iii.  3,  2, 
Clay,  iv.  3,  5,  3. 
Cloves,  iii.  3,  1,  iii.  3,  2. 
Cnicus  acarna,  v.  3,  1. 
Cocculus  indicus,  ii.  3,  I. 


Cochlearia  armoracia,  iii.  3,  8,  iv.  3,  4. 

hortenfis,  iv.  3,  4. 

Cold,  continued  application  of,  vii.  2,3. 
interrupted,  vii.     2,  3,  iii.  3,  1,  7. 
excefHve,  vii.  2,  3* 
firft  affects    lymphatics,  vii.  2,  3. 
produces    rheum  from  the  nofe, 

vii.  2,  3. 
produces  quick    anhelation.    vii. 

2,3. 

increafes  digeftion,  vii.  2, 3. 
Cold  fit  eafier  prevented  than  remov- 
ed, ii.  2,  1. 

Colic  from  leaft,  v.  2,  2,  2. 
Condiments,  i.  2,  7. 
Convolvulus  fcammonium,  v.  3,  2. 
Convu3fions,iv.  2,  8. 
Cookery,  i.  2,  3,  5. 
Copaiva  balfam,  iii.  3,  4,  3. 
Cowhage,  iii.  2,  7,  vii.  3,  1 1. 
Crab-juice,  iv.  2,  2. 
Cream,  i.  2,  3,  2,  i.  2,  2,  2. 
Cucumis  colocynthis,  v.  3,  ?. 
Cynara  fcolymus,  iv.  3,  3. 
Cynogloflum,  ii.  3,  1. 
D 

Dandelion,  vi.  3, 4. 
Datura  ftramonium,  ii.  3,  1. 
Daucus  fylveftris,  iii.  3,  4,  4. 
Delphinium  ftavifagria,  ii.  3,  1. 
Diabetes,  iv.  2,  5. 

warm  bath  in,  vi.  2,  4. 
Diaphoretics,  iii.  ~\  1.  iii.  2,  1,  2. 

beft  in  the  morning,  iii.  ?,, 

1,  5. 

Diarrhoea,  vi.  2,3. 
Digeftion  injured  by  cold,  iii.  2.  I. 

increafed  by    cold,  vii.  2, 3. 
Digitalis,  iv.  2,  3,  7,  v.  2,  1,2. 

tincture  of,  iv.  2,  3,  7. 
Dragon's  blood,  iv.  3,  5,  2. 
Dropfy,  iv.  2,  3,  4,  iv.  2,  6,  7,  iv.  2,5,7. 

E 

Ears,  eruption  behind,  Jv.  2,  9,  2. 
Earth  of  bones,  iv.  2,  5. 
of  alum,  vi.  2,  4. 
calcareous,  iv.  2,  5,  3,  vi.  2,  4,  i.t 

2,  4,  3. 
Eggs,  i.  2,  1,4. 
Egg-fhells  diuretic,  iii.  2,  4. 
Electricity,  ii.  2,  2,  2,  iv.  2,9. 
Emetics, how  they  act,  v.  2, 1. 
F.rrhines  mild,  iii.  2,  9. 

in  hydrocephalus,  v.  2,  3,  1-, 
violent,  v.  2,  3. 
inhead-ach,  v.  2,  3,  1. 
Eryfipelas,  iv.  2,  9. 
EfTential  oils,  ii,  2,  3, 

Ether, 


INDEX  OF  THE  ARTICLES—FART  III. 


Ether  vitriolic,  ii.  2,  3,   Hi.    3,  1,     vi. 

3,  1. 

in  aicarides,  vii.  1,  2. 
to  purify,  ii.  1,  3. 
Etiolation,  i.  2,  3,  4. 
Euphorbium,v.  3,  3. 
E*ercife,  iii.  3, 1,  6,  ii.2,  6. 
Eyes  inflamed,  ii.  2,  2,  2,  iv.  2,  3. 

F 

Famine,  times  of,  i.  2,  3,  5  and  6. 
Fe^r,  v.  2,  4. 

Feathers,  fmoke  of,  vi.  3,  6. 
Fennel,  iii.  3,  4, 4. 
Ferula  afafc^ida,  iii.  3,  3. 
Fi{h,i.2,  1,  2,i.2,  1,  5. 
Flannel  lliirt,  ii.  2-  2. 
Flefh  of  animals,  i.  2,  1. 
Fluke- worm,  iv.  2, 6. 
Foxglove,  iv.  2,  3,  7,  v.  2,  !,  v.  2,  4. 

tincture  of,  iv.  2,  3,  7. 
Fridlion,  Ji.  2, 5,  iii.  3,  1,6. 

G 

Galanthus  nivalis,  vii.  3,  3. 
Galbanum,  vi.  3,  1. 
Gall-ftones,  iv.  2,  6. 
Galls  of  oak,  iv.  3,5. 
Garlic,  iii.  3,  3. 
Gentiana  centaureum,  iv.  3,  3. 

lutea,  iv.  3,  3. 
Ginger, iii.  3,  l,iii. 3,  4. 
Gonorrhoea,  iv.  2,  2,  iii.  2, 4. 
Gout,  iv.  2,  11,2. 
Guaiacum,  iii.  3,  1. 
Gum  arabic,  iii. 3,  3,  3. 

trag  canth,  iii.  3,  3,  3. 
Glycyrrhiza  giabra,  iii.  3,  3,  8. 
Gravel,  v.  2,  4, 4. 

H 
Hartfhorn,  fpirit  and  fait  of,  iii.  3,  3, 

iii.  3,  1,  vi.  3,  4. 
calcined,  iv.  2,  5,  vi.  2,  3. 
Haemorrhages,  iv.  2,  4,  4,  iv.  2,  6,  2. 
Hasmatoxylon    campechianum,    iv.  3, 

5,2. 

Hay,  infufion  of,  i.  2,  3,  6. 
Head-ach,  fnuffin,  v.  2,  3,  1. 
Heat,  ii.  2,  2,  1.     See  Bath. 

an  univeifal  folvent,  vii.  2,  2. 
Helenium,  iii.  3, 3,  2. 
Herpes,  iv.  2,  1,  iv.  2,  9. 
Hernngs,  red,  iii.  3,  1,  4. 
Honey,  iii.  3,  3,  3,  iii.  3,  5,  1. 
Hop  in  beer,  why  noxious,  iv.  2,  3,  6, 

iv.  2, 11,  2. 

Hordeum  diflichon,  iii.  3,  3,  3. 
Humulus  lupulus.,  iv.  2,  3,iv.  2,  11. 
Hydrargyrus  vitriolatus,  v.  2, 3. 
Hyfteric  difeafe,  vi.  2, 1. 
pains,  vi.  2,  1. 
convufions,  vi.  2, 1. 


Jalapium.  iii.  3,  5,  5. 
Japan  earth,  iv.  3,  5,  2, 
Jaundice,  iv.  2,  6,  3. 
Ileus  vi.  2,  5. 
Incitantia,  ii. 

Intermittents.     See  Agues. 
Inverted  motions,  vi.  2,  1. 

in   hyfteric    difeafe, 

vi.2,  1. 

of  the   ftomach,  vi. 
2,  2. 

inteftinal  ca- 
nal, vi.  1 , 5. 
of  lymphatics,  vi.  2,3. 
Inula  helenium,iii.  3,  3,  2. 
Ipecacuanha,  v.  2,  1. 
Iron,  ruft  of,  iv.  3,  6. 
Irritability  prevented,  iv.  2,  3,  3. 
Itch,  iv.  2,  1,3. 
Inflammation  of  the  bowels,  v.  2,  2,  2. 

L 
Laurus  camphora,  iii.  3,  1. 

cinnamomum,  iii.  3,  1. 
faflafras,  iii.  3,  1. 
Lead,  iv.  3,  6. 

colic  from,  v.  2,  2,  2. 
fugar  of,  iv.  2,  9. 
Leeks,  iii.  3,  3,  1. 
Legs,  ulcers  of,  iv.  2, 10. 
fwelled,  iv.  2,  3,  8. 
Lemon-juice,  iv.  2, 1,  iv.  2,  2. 
Leontodon  taraxacum,  iv.  3,  4. 
Life  fliortened  by  great  ftimulus,  u.  I . 
Lime,  i.  2,  4,  3, 
Liquorice,  iii.  3,  3,  3. 
Liver  inflamed,  iv.  2,  6. 
Logwood,  iv.  3, 5,  2. 
Lymphatics,  inverted  motions  of,  v.  2.1. 

M 

Manganefe,  ii.  S,  4. 
Magnefia  alba,  iii.  3,  5, 8. 
Malt,  i.  2,  3,  5. 
Manna,  iii.  3,  5. 
Marfh-mallows,  iii.  3,  3,  S, 
Marjoram,  iii.  3,  9. 
Marum,iii.  3,  9. 
Maftich,  iii.  3,  2,  iii.  3,  3. 
Menianthes  trifoliata,  iv.  3, 3. 
Menifpermum  cocculus,  ii.  3, 1. 
Menftruation  promoted,  iv.  2,  6,6*. 

reprefled,  iv.  2, 6, 6. 
Mercury,  iii.  3,  2,  vi.  2,  2. 

preparations  of,  iv.  3,  7,  iv,, 

2,  7,  iv  2,  9. 

injected  as  a  clyfter,  vi.  3,  5^ 
Metallic  falts,  iv.  2,  6. 
Milk,  i.  2,  2. 

Mimofa  nilotica,  iii.  3,  3,  3. 
catechu,  iv.  3, 5,  %, 


INDEX  OF  THE  ARTICLES— PART  III. 


j^lint,  vi.  3,  3. 
Mortification,  iv.  2,  9. 
Mucilage,  vegetable,  vii.  3,  3. 
Mucus,  animal,  vii.  3,  5. 
Mufhrooms,  i.  2,  1,  2. 
Mufk,  vi. -^  1,  vi.  3,1. 
Muftard,  iv.  3,  4.     See  Sinapifm. 

N 

Naufea,  in  fevers,  vii.  2,  5. 
Neutral  falts  diuretic,  why,  iii.  2,  4. 

increafe  fome  coughs,  iii.  2,  4. 
increafe  heat  of  urine,  iii.  2,  4. 
&icotiana  tabacum,  iii.  35  9,  ii.  3,  1. 
Nitre,  iii.  3,  4,  v.  2,  4. 
Nutmeg,  iii.  2,  1. 
Nutrientia,  i. 

O 

Oil  of  almonds,  iii.  3.  5, 4. 
in  cream,  i.  2,3,2. 
of  amber,  vi.  2,  1. 
expreffed,  externally,  iii,  2,  3. 
eflential,  ii.  2,  3,  iii.  3,  2. 
Oiled  filk,  vii.  3,  IS. 
Oleum  animale,  vi.  2,  l,vi.  3,4. 

ricmi,  iii.  3,  5,  4. 
Onions,  iii.  3,  3. 
Opium,  ii.  2,  1,  2,  iv    1,  2. 

in  nervous  pains,  ii    2,  1,5. 
in  inflammatory  pains,  ii.  1, 1,6. 
increafes  all    fecretions  and  ab- 

forptions,  ii.  2,  1,  1. 
abforption     after    evacuation, 

iv.  2,  8,  2,  ii.  2,  1,  3. 
flops  fweats,  iv.  2,  1 ,  2. 
intoxicates,  ii.  2,  1,  1. 
Oranges,  their  peel,  iv.  3,  3, 
Orchis,  vii.  3,  3 
Oxygen  gas,  ii.    2,  4,  i.  2,  5,  iii.  2,  11, 

iv.  1 , 4. 

produces  and  heals  ulcers, 
iv.  2, 7. 

P 

Pains,  periodic,  cured  by  opium,  ii.  2,1. 
Papin's  digefter,i.  2,  3/5. 
Papaver  fomniferum,  ii.'S,  1,  iv.  :),  2. 

See  Opium. 

Pareira  brava,  iii.  3,  44  4. 
Parfley,  iii.  3,  4. 
Paflions,  ii.  2,  5. 
Paflurage,  i.  2,  3,  7. 
Pepper,  iii.  3,  1. 
Penpneumony}  iv.  2,  8,  2. 
Perfpiration  in  a  morning,  iii.  2,  1. 

not  an  excrement,  iii.  2,  1. 
Peru,  balfam  of,  iii.  3,  5,  4. 
PetechirE,  iv.  2,  4,  2. 
Pimento,  iii.  3,  1. 
Piper  indicum,  iii    3,    1. 
Piftacia  lentifcus,  iii.  3,  2. 
Pix  liquids,  iii.  3,  2. 


Phofphorus,  iii.  2,  6. 

Plafter-bandage,  iv.  2, 1Q. 

Pleurify,  iv.  2,  8,  2. 

Polygala  feneka,  iii.  3,  3,  2, 

Poppy.     See  Papaver. 

Portland's  powder  noxious,  why,  iv.  2. 

11,2. 

Potatoe-bread,  i   2,  3,  4. 
Potentilla,iv   3,  5. 
Powder,  of  iron,  iv.  2,  6,  6. 
Prunes,  iii.  3,  5,  1. 
Prunus  domeflica,iii.   3,  5, 1. 
fpinofa,  iv.  3,  1. 
lauro-cerafus,  ii.  3,  1. 
Pulegium,  vi.   3,  3. 
Pulfe,  intermittent,  relieved  by  arfenic. 

iv.  2,  6. 

Pyrethrum,  iii.  3,2. 
Pyrus  malus,  vii. 

cydonia,iv.  3, 

Q 

Quafiia,  iv  2,  2. 
Quince,  iv.  3,  1. 
Quiuquefolium,  iv.  3,5. 

R 

Ri tafia,  why  deftructive,  ii.  2, 1. 
Reaction,  iv.  1,  10. 
Refin  diuretic,  iii.  2, 4,  vi.  2,  4. 
Rhamnus  catharticus,  v.  3,  2. 
Rheumatifm,  iv.  2,  4,  5,  iv.  2, 10,  12. 
Rheum  palmatum.     See  Rhubarb. 
Rhubarb,  iii.  2,  l,iv.  2,  5, 1,  iii.  3,5,5. 
cauJfc-;  conftipation,  why,  iii. 

-',  1,  I- 
Rice,  vii. 
Rofes,  iv.  3,  5. 
Rot  in  flieep,  iv.  2,  6%. 

S 

Sagapenum,  vi.  3,  1. 
Sago,  vii.  3. 
Salivation  not  neceflary,  iv.  2, 7. 

hyftericjV.  2,  3. 

Salt,  common,  unwholefomc,  iii.  1,  1- 
murintic,  iii.  3,  1. 
in  clyfters,  iii.  2,  7. 
Salts,  why  diuretic,  iii.  2,  4. 

neutral,  iii.  3,  5,  S,  iii.  2,  4. 
improper   in    coughs  and  gonor- 
rhoea, iii.  2,  4. 
Salt  fiili  and  fait  meat  increafe  perfpi- 

ration,  iii.  2,  1. 
SafTafras,  iii.  3,  1.    . 
Scammony,  v.  2,  2. 
Scarcity,  times  of,  i.  2, 3, 5  and  6. 
Sciila  maritima,  v.  i2,  2,  iv.  2,  3,  iii.  3? 

S,  v.  2,  3. 

Scorbutic  legs,  iv.  2,  10. 
Scrofulous  tumours,  ii.  2, 4,  iv.  2,  9. 
Sea-water,  iii.   3,  5,  3. 
Secernentiajiii, 

Secretion 


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